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Climate change mitigation is action to limit
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
by reducing emissions of greenhouse gases or removing those gases from the atmosphere. The recent rise in global average temperature is mostly caused by emissions from fossil fuels burning (
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...
,
oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...
, and
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
). Mitigation can reduce emissions by transitioning to sustainable energy sources, conserving energy, and increasing efficiency. In addition, can be removed from the atmosphere by enlarging forests, restoring wetlands and using other natural and technical processes, which are grouped together under the term of
carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in lan ...
. Solar energy and
wind power Wind power or wind energy is mostly the use of wind turbines to generate electricity. Wind power is a popular, sustainable, renewable energy source that has a much smaller impact on the environment than burning fossil fuels. Historically ...
have the highest climate change mitigation potential at lowest cost compared to a range of other options. Variable availability of sunshine and wind is addressed by energy storage and improved electrical grids, including long-distance electricity transmission, demand management and diversification of renewables. As low-carbon power is more widely available, transportation and heating can increasingly rely on these sources.Ram M., Bogdanov D., Aghahosseini A., Gulagi A., Oyewo A.S., Child M., Caldera U., Sadovskaia K., Farfan J., Barbosa LSNS., Fasihi M., Khalili S., Dalheimer B., Gruber G., Traber T., De Caluwe F., Fell H.-J., Breyer C
Global Energy System based on 100% Renewable Energy – Power, Heat, Transport and Desalination Sectors
Study by Lappeenranta University of Technology and Energy Watch Group, Lappeenranta, Berlin, March 2019.
Energy efficiency Energy efficiency may refer to: * Energy efficiency (physics), the ratio between the useful output and input of an energy conversion process ** Electrical efficiency, useful power output per electrical power consumed ** Mechanical efficiency, a ra ...
is improved using
heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing ...
s and electric vehicles. If industrial processes must create carbon dioxide,
carbon capture and storage Carbon capture and storage (CCS) or carbon capture and sequestration is the process of capturing carbon dioxide (CO2) before it enters the atmosphere, transporting it, and storing it (carbon sequestration) for centuries or millennia. Usually th ...
can reduce net emissions. Greenhouse gas emissions from agriculture include
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
as well as
nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...
. They can be reduced by farming fewer cattle. Climate change mitigation policies include:
carbon pricing Carbon pricing (or pricing), also known as cap and trade (CAT) or emissions trading scheme (ETS), is a method for nations to reduce global warming. The cost is applied to greenhouse gas emissions in order to encourage polluters to reduce the co ...
by
carbon tax A carbon tax is a tax levied on the carbon emissions required to produce goods and services. Carbon taxes are intended to make visible the "hidden" social costs of carbon emissions, which are otherwise felt only in indirect ways like more sev ...
es and
carbon emission trading Emission trading (ETS) for carbon dioxide (CO2) and other greenhouse gases (GHG) is a form of carbon pricing; also known as cap and trade (CAT) or carbon pricing. It is an approach to limit climate change by creating a market with limited ...
, easing regulations for renewable energy deployment, reductions of
fossil fuel subsidies Fossil fuel subsidies are energy subsidies on fossil fuels. They may be tax breaks on consumption, such as a lower sales tax on natural gas for residential heating; or subsidies on production, such as tax breaks on exploration for oil. Or ...
, and divestment from fossil fuels, and
subsidies A subsidy or government incentive is a form of financial aid or support extended to an economic sector (business, or individual) generally with the aim of promoting economic and social policy. Although commonly extended from the government, the ter ...
for
clean energy Clean may refer to: * Cleaning, the process of removing unwanted substances, such as dirt, infectious agents, and other impurities, from an object or environment * Cleanliness, the state of being clean and free from dirt Arts and media Music A ...
. Current policies are estimated to produce global warming of about 2.7 °C by 2100. This warming is significantly above the 2015 Paris Agreement's goal of limiting global warming to well below 2 °C and preferably to 1.5 °C.


Definitions

The Intergovernmental Panel on Climate Change (IPCC) defines ''mitigation (of climate change)'' as "a human intervention to reduce emissions or enhance the sinks of greenhouse gases".IPCC, 2021
Annex VII: Glossary
atthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C.  Méndez, S. Semenov, A. Reisinger (eds.) I
Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
[Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, doi:10.1017/9781009157896.022.
Some publications describe Solar geoengineering, solar radiation management (SRM) as a ''climate mitigation technology.'' SRM does not attempt to address the root cause of global warming but would work by changing the way solar radiation is received by Earth. Examples include reducing the amount of sunlight reaching the surface, reducing optical thickness and cloud lifetime, and changing surface reflectivity. The Intergovernmental Panel on Climate Change, IPCC describes SRM as a "climate risk reduction strategy" or "supplementary option" but not as a climate mitigation option.IPCC (2022
Chapter 14: International cooperation
i
Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
It is part of a range of radiation modification measures not related to greenhouse gas mitigation.


Categories of mitigation measures

Climate change mitigation focuses on reducing and recapturing
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and ...
—primarily carbon dioxide,
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
,
nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...
, and fluorinated gases. Mitigation measures can be approached in parallel, as there is no single pathway to limit global warming to 1.5 or 2 °C. Mitigation measures can be grouped into the following four categories. # Sustainable energy and sustainable transport # Energy conservation (this includes efficient energy use) # For agricultural production and industrial processes:
sustainable agriculture Sustainable agriculture is farming in sustainable ways meeting society's present food and textile needs, without compromising the ability for current or future generations to meet their needs. It can be based on an understanding of ecosystem ser ...
and
green industrial policy Green industrial policy (GIP) is strategic government policy that attempts to accelerate the development and growth of green industries to transition towards a low-carbon economy. Green industrial policy is necessary because green industries such ...
# Enhancing
carbon sink A carbon sink is anything, natural or otherwise, that accumulates and stores some carbon-containing chemical compound for an indefinite period and thereby removes carbon dioxide () from the atmosphere. Globally, the two most important carbon si ...
s:
Carbon dioxide removal Carbon dioxide removal (CDR), also known as negative emissions, is a process in which carbon dioxide gas () is removed from the atmosphere and sequestered for long periods of time. Similarly, greenhouse gas removal (GGR) or negative greenho ...
and
carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in lan ...


Timescales

Tools for mitigation vary in the timescales needed for them to have an impact on emissions. For example most countries can rapidly implement solar or wind power as they are mature technologies, which allows coal-fired powers plant to be retired or fewer gas-fired power plants to be built. The mitigation tools that can yield the most emissions reductions in the short time remaining before 2030 are solar energy, reduced conversion of
forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
s and other
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
s,
wind energy Wind power or wind energy is mostly the use of wind turbines to generate electricity. Wind power is a popular, sustainable, renewable energy source that has a much smaller impact on the environment than burning fossil fuels. Historically, w ...
,
carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in lan ...
in agriculture, followed by the group of ecosystem restoration, afforestation, and
reforestation Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting. Management A debat ...
. Elimination of certain other sources of emissions, such as those during cement production, will require research, technology development, and conversion or replacement of facilities, and therefore will take much longer.


Goal, benefits and risks

The overall goal of climate change mitigation is: "to preserve a biosphere which can sustain human civilization and the complex of ecosystem services which surround and support it. This means reducing anthropogenic greenhouse gas emissions towards
net zero Carbon neutrality is a state of net-zero carbon dioxide emissions. This can be achieved by balancing emissions of carbon dioxide with its removal (often through carbon offsetting) or by eliminating emissions from society (the transition to the " ...
to limit the warming, with global goals agreed in the Paris Agreement."


Co-benefits

There are also
co-benefits of climate change mitigation Co-benefits of climate change mitigation are the positive benefits related to mitigation measures which reduce greenhouse gas emissions or enhance carbon sinks. The beneficial or adverse impacts of deploying climate-change mitigation measures ar ...
. For example, in the transport sector, possible co-benefits of mitigation strategies include: air quality improvements, health benefits, equitable access to transportation services, reduced traffic congestion, and reduced material demand.IPCC (2022
Summary for policy makers
i
Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
The increased use of
green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combi ...
and blue infrastructure can reduce the
urban heat island An urban heat island (UHI) is an urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference is usually larger at night than during the day, and is most apparen ...
effect and
heat stress Hyperthermia, also known simply as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme ...
on people, which will improve the mental and physical health of urban dwellers.IPCC (2022
Technical Summary
I
Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
Climate change mitigation might also lead to less inequality and poverty. Mitigation measures may have many health co-benefits – potential measures can not only mitigate future health impacts from climate change but also improve health directly. Globally the cost of limiting warming to 2 °C is less than the value of the extra years of life due to cleaner air - and in India and China much less. Air quality improvement is a near-term benefit among the many societal benefits from climate change mitigation, including substantial health benefits. Studies suggest that demand-side climate change mitigation solutions have largely beneficial effects on 18 constituents of
well-being Well-being, or wellbeing, also known as wellness, prudential value or quality of life, refers to what is intrinsically valuable relative ''to'' someone. So the well-being of a person is what is ultimately good ''for'' this person, what is in th ...
. Some mitigation measures have co-benefits in the area of
climate change adaptation Climate change adaptation is the process of adjusting to current or expected effects of climate change.IPCC, 2022Annex II: Glossary öller, V., R. van Diemen, J.B.R. Matthews, C. Méndez, S. Semenov, J.S. Fuglestvedt, A. Reisinger (eds.) InClimat ...
.IPCC (2022
Chapter 8: Urban systems and other settlements
i
Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
This is for example the case for many
nature-based solutions The term Nature-based solutions (NBS) refers to the sustainable management and use of natural features and processes to tackle socio-environmental challenges. These challenges include issues such as climate change ( mitigation and adaptation), ...
.IPCC (2022
Chapter 4: Mitigation and development pathways in the near- to mid-term
i
Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
Examples in the urban context include urban
green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combi ...
and blue infrastructure which provide mitigation as well as adaptation benefits. This can be in the form of urban forests and street trees,
green roof A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage ...
s and
walls Walls may refer to: *The plural of wall, a structure *Walls (surname), a list of notable people with the surname Places * Walls, Louisiana, United States * Walls, Mississippi, United States * Walls, Ontario, neighborhood in Perry, Ontario, C ...
,
urban agriculture Urban agriculture, urban farming, or urban gardening is the practice of cultivating, processing, and distributing food in or around urban areas. It encompasses a complex and diverse mix of food production activities, including fisheries and fo ...
and so forth. The mitigation is achieved through the conservation and expansion of carbon sinks and reduced energy use of buildings. Adaptation benefits are provided for example through reduced heat stress and flooding risk.


Risks and negative side effects

Mitigation measures can also have negative side effects. This is highly context-specific and can also depend on the scale of the intervention. In agriculture and forestry, mitigation measures can affect biodiversity and ecosystem functioning. In the area of renewable energies, mining for metals and minerals can increase mining threats to conservation areas. To address one of these issues, there is research into ways to recycle solar panels and
electronic waste Electronic waste or e-waste describes discarded electrical or electronic devices. Used electronics which are destined for refurbishment, reuse, resale, salvage recycling through material recovery, or disposal are also considered e-waste. Inform ...
in order to create a source for materials that would otherwise need to be mined. Discussions about risks and negative side effects of mitigation measures can "lead to deadlock or a sense that there are intractable obstacles to taking action".


Greenhouse gas emissions

Greenhouse gas emissions from human activities strengthen the
greenhouse effect The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly ...
, contributing to
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
. Most is
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
from burning fossil fuels:
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...
,
oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...
, and
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
. Human-caused emissions have increased
atmospheric carbon dioxide Carbon dioxide in Earth's atmosphere is a trace gas that plays an integral part in the greenhouse effect, carbon cycle, photosynthesis and oceanic carbon cycle. It is one of several greenhouse gases in Earth's atmosphere that are contributin ...
by about 50% over pre-industrial levels. Emissions in the 2010s averaged 56 billion tons a year, higher than ever before. Accounting of greenhouse gas emissions by sector can be done in different ways. An established method by
Our World in Data Our World in Data (OWID) is a scientific online publication that focuses on large global problems such as poverty, disease, hunger, climate change, war, existential risks, and inequality. It is a project of the Global Change Data Lab, a re ...
groups them as follows (data for 2016): Energy (electricity, heat and transport): 73.2%, direct industrial processes: 5.2%, waste: 3.2%, agriculture, forestry and land use: 18.4%.
Electricity generation Electricity generation is the process of generating electric power from sources of primary energy. For utilities in the electric power industry, it is the stage prior to its delivery ( transmission, distribution, etc.) to end users or its s ...
and
transport Transport (in British English), or transportation (in American English), is the intentional movement of humans, animals, and goods from one location to another. Modes of transport include air, land ( rail and road), water, cable, pipelin ...
are major emitters, the largest single source being coal-fired power stations with 20% of all greenhouse gas emissions.
Deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
and other changes in land use also emit carbon dioxide and
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
. The largest source of anthropogenic
methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...
is
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people t ...
, closely followed by gas venting and
fugitive emissions Fugitive emissions are leaks and other irregular releases of gases or vapors from a pressurized containment – such as appliances, storage tanks, pipelines, wells, or other pieces of equipment – mostly from industrial activities. In addition ...
from the fossil-fuel industry. The largest agricultural methane source is
livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animal ...
. Agricultural soils emit
nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...
partly due to
fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
s. The problem of fluorinated gases from refrigerants has been politically solved now so many countries have ratified the Kigali Amendment. Current emission rates are on average 6.5 tonnes per person per year (with large variations from one country to another).


By type of greenhouse gas

Carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
() is the dominant emitted greenhouse gas, while
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
() emissions almost have the same short-term impact.
Nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...
(N2O) and fluorinated gases (F-Gases) play a minor role.
Fugitive emission Fugitive emissions are leaks and other irregular releases of gases or vapors from a pressurized containment – such as appliances, storage tanks, pipelines, wells, or other pieces of equipment – mostly from industrial activities. In addition ...
s from the fossil fuel industry are estimated to have been the largest source of methane in 2021. The largest agricultural methane source is livestock. Livestock and manure are 5.8% of all greenhouse gas emissions, although this depends on the time horizon used for the
global warming potential Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time ...
of the respective gas. It can be reduced by reductions in dairy products and
meat consumption Meat is animal flesh that is eaten as food. Humans have hunted, farmed, and scavenged animals for meat since prehistoric times. The establishment of settlements in the Neolithic Revolution allowed the domestication of animals such as chick ...
. Greenhouse gas (GHG) emissions are measured in equivalents determined by their
global warming potential Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time ...
(GWP), which depends on their lifetime in the atmosphere. There are widely-used greenhouse gas accounting methods that convert volumes of methane, nitrous oxide and other greenhouse gases to carbon dioxide equivalents. Estimations largely depend on the ability of oceans and land sinks to absorb these gases. Short-lived climate pollutants (SLCPs) including
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
, hydrofluorocarbons (HFCs),
tropospheric ozone Ground-level ozone (O3), also known as surface-level ozone and tropospheric ozone, is a trace gas in the troposphere (the lowest level of the Earth's atmosphere), with an average concentration of 20–30 parts per billion by volume (ppbv), with c ...
and
black carbon Chemically, black carbon (BC) is a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter). Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fuel ...
persist in the atmosphere for a period ranging from days to 15 years; whereas carbon dioxide can remain in the atmosphere for millennia.


Needed emissions cuts

The annual "Emissions Gap Report" by
UNEP The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the United Nations Conference on ...
stated in 2022: "To get on track for limiting global warming to 1.5°C, global annual GHG emissions must be reduced by 45 per cent compared with emissions projections under policies currently in place in just eight years, and they must continue to decline rapidly after 2030, to avoid exhausting the limited remaining atmospheric
carbon budget A carbon budget is "the maximum amount of cumulative net global anthropogenic carbon dioxide () emissions that would result in limiting global warming to a given level with a given probability, taking into account the effect of other anthropogen ...
."United Nations Environment Programme (2022)
Emissions Gap Report 2022: The Closing Window — Climate crisis calls for rapid transformation of societies
Nairobi.
The report also points out that the world should focus on "broad-based economy-wide transformations" instead of focusing on incremental change. In 2022, the Intergovernmental Panel on Climate Change (IPCC) released its Sixth Assessment Report on climate change, warning that greenhouse gas emissions must peak before
2025 Predicted and scheduled events *January 1 ** In the United States, books, films, and other works published in 1929 will enter the public domain, assuming there are no changes made to copyright law. ** The Federal Aviation Administration, ...
at the latest and decline 43% by 2030, in order to likely limit global warming to 1.5 °C (2.7 °F). Secretary-general of the United Nations, António Guterres, clarified that for this "Main emitters must drastically cut emissions starting this year".


Emissions and economic growth

Economic growth is a key driver of CO2 emissions. As the economy expands, demand for energy and energy-intensive goods increases, pushing up CO2 emissions. On the other hand, economic growth may drive technological change and increase energy efficiency. Economic growth may be associated with specialization in certain economic sectors. If specialization is in energy-intensive sectors, specifically carbon energy sources, then there will be a strong link between economic growth and emissions growth. If specialization is in less energy-intensive sectors, e.g. the services sector, then there might be a weak link between economic growth and emissions growth. Much of the literature focuses on the "environmental
Kuznets curve The Kuznets curve () expresses a hypothesis advanced by economist Simon Kuznets in the 1950s and 1960s. According to this hypothesis, as an economy develops, market forces first increase and then decrease economic inequality. The Kuznets curve ...
" (EKC) hypothesis, which posits that at early stages of development, pollution per capita and GDP per capita move in the same direction. Beyond a certain income level, emissions per capita will decrease as GDP per capita increase, thus generating an inverted-U shaped relationship between GDP per capita and pollution. However, the
econometrics Econometrics is the application of statistical methods to economic data in order to give empirical content to economic relationships. M. Hashem Pesaran (1987). "Econometrics," '' The New Palgrave: A Dictionary of Economics'', v. 2, p. 8 p. 8 ...
literature did not support either an optimistic interpretation of the EKC hypothesis – i.e., that the problem of emissions growth will solve itself – or a pessimistic interpretation – i.e., that economic growth is irrevocably linked to emissions growth. Instead, it was suggested that there was some degree of flexibility between economic growth and emissions growth.


Energy systems

The energy system, which includes the use and delivery of energy, is the main emitter of . Reducing energy sector emissions is therefore essential to limit warming. Rapid and deep reductions in the and greenhouse gas emissions from energy system are needed to limit global warming to well below 2 °C. Recommended measures includes: "reduced fossil fuel consumption, increased production from low- and zero carbon energy sources, and increased use of electricity and alternative energy carriers". Most scenarios and strategies expect to see a major increase in the use of renewable energy in combination with increased energy efficiency measures.


Renewable energy

Wind and sun can be sources for large amounts of low-carbon energy at competitive production costs. But even in combination, generation of
variable renewable energy Variable renewable energy (VRE) or intermittent renewable energy sources (IRES) are renewable energy sources that are not dispatchable due to their fluctuating nature, such as wind power and solar power, as opposed to controllable renewable ener ...
sometimes does not match demand in some places. This can be tackled by extending grids over large areas with a sufficient capacity or by using energy storage (see also: forms of grid energy storage) and by other means.
Load management Load management, also known as demand-side management (DSM), is the process of balancing the supply of electricity on the network with the electrical load by adjusting or controlling the load rather than the power station output. This can be ach ...
of industrial energy consumption can help to balance the production of renewable energy production and its demand. In many places electricity production by
hydro power Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water to produce electricity or to power machines. This is achieved by converting the gravitational potential or kinetic energy of a w ...
can follow the energy demand. Flexible supply and demand can be incentivized by variable energy prices. The deployment of renewable energy would have to be accelerated six-fold though to stay under the "2 °C target". The competitiveness of renewable energy is a key to a rapid deployment. In 2020, onshore wind and solar photovoltaics were the cheapest source for new bulk electricity generation in many regions. Storage requirements cause additional costs. A
carbon price Carbon pricing (or pricing), also known as cap and trade (CAT) or emissions trading scheme (ETS), is a method for nations to reduce global warming. The cost is applied to greenhouse gas emissions in order to encourage polluters to reduce the co ...
can increase the competitiveness of renewable energy.


Solar energy

Solar
photovoltaics Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially ...
(PV) has become the cheapest way to generate electricity in many regions of the world. The
growth of photovoltaics Worldwide growth of photovoltaics has been close to exponential between 1992 and 2018. During this period of time, photovoltaics (PV), also known as solar PV, evolved from a niche market of small-scale applications to a mainstream electricit ...
is exponential and has doubled every three years since the 1990s. In the summer, PV power generation follows the daily demand curve. A different technology is concentrated solar power (CSP) using mirrors or lenses to concentrate a large area of sunlight onto a receiver. With CSP, the energy can be stored for a few hours, providing supply in the evening. This can outweigh the higher costs compared to PV.
Solar water heating Solar water heating (SWH) is heating water by sunlight, using a solar thermal collector. A variety of configurations are available at varying cost to provide solutions in different climates and latitudes. SWHs are widely used for residential a ...
doubled between 2010 and 2019.


Wind power

Regions in the higher northern and southern latitudes have the highest potential for wind power.
Offshore wind power Offshore wind power or offshore wind energy is the generation of electricity through wind farms in bodies of water, usually at sea. There are higher wind speeds offshore than on land, so offshore farms generate more electricity per amount of c ...
currently has a share of about 10% of new installations. Offshore wind farms are more expensive but the units deliver more energy per installed capacity with less fluctuations. In most regions, wind power generation is higher in the winter when PV output is low; for this reason, combinations of wind and solar power are recommended.


Others

Other well-established renewable energy forms include hydropower, bioenergy and geothermal energy: *
Hydroelectricity Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...
is electricity generated by
hydropower Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water to produce electricity or to power machines. This is achieved by converting the gravitational potential or kinetic energy of a w ...
and plays a leading role in countries like Brazil, Norway and China. but there are geographical limits and environmental issues.
Tidal power Tidal power or tidal energy is harnessed by converting energy from tides into useful forms of power, mainly electricity using various methods. Although not yet widely used, tidal energy has the potential for future electricity generation. Ti ...
can be used in coastal regions. * Bioenergy can be in the form of
biogas Biogas is a mixture of gases, primarily consisting of methane, carbon dioxide and hydrogen sulphide, produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste and food waste. It is a ...
plants which can provide dispatchable electricity generation, and heat when needed. A common concept is the co-fermentation of energy crops mixed with manure in agriculture. Burning plant-derived biomass releases , but it has still been classified as a renewable energy source in the EU and UN legal frameworks because photosynthesis cycles the back into new crops. How a fuel is produced, transported and processed has a significant impact on lifecycle emissions. Renewable biofuels are starting to be used in aviation. * Geothermal power is electrical power generated from geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal electricity generation is currently used in 26 countries,Geothermal Energy Association
Geothermal Energy: International Market Update
May 2010, p. 4-6.
while
geothermal heating Geothermal heating is the direct use of geothermal energy for some heating applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ of ...
is in use in 70 countries.Moomaw, W., P. Burgherr, G. Heath, M. Lenzen, J. Nyboer, A. Verbruggen
2011: Annex II: Methodology. In IPCC: Special Report on Renewable Energy Sources and Climate Change Mitigation (ref. page 10)
/ref>


Integrating variable renewable energy

To deliver reliable electricity from
variable renewable energy Variable renewable energy (VRE) or intermittent renewable energy sources (IRES) are renewable energy sources that are not dispatchable due to their fluctuating nature, such as wind power and solar power, as opposed to controllable renewable ener ...
sources such as wind and solar, electrical power systems require flexibility. Most electrical grids were constructed for non-intermittent energy sources such as coal-fired power plants. As larger amounts of solar and wind energy are integrated into the grid, changes have to be made to the energy system to ensure that the supply of electricity is matched to demand. In 2019, these sources generated 8.5% of worldwide electricity, a share that has grown rapidly. There are various ways to make the electricity system more flexible. In many places, wind and solar generation are complementary on a daily and a seasonal scale: there is more wind during the night and in winter when solar energy production is low. Linking different geographical regions through long-distance transmission lines allows for further cancelling out of variability. Energy demand can be shifted in time through
energy demand management Energy demand management, also known as demand-side management (DSM) or demand-side response (DSR), is the modification of consumer demand for energy through various methods such as financial incentives and behavioral change through education. Us ...
and the use of
smart grids A smart grid is an electrical grid which includes a variety of operation and energy measures including: *Advanced metering infrastructure (of which smart meters are a generic name for any utility side device even if it is more capable e.g. a f ...
, matching the times when variable energy production is highest. With grid energy storage, energy produced in excess can be released when needed. Further flexibility could be provided from
sector coupling Power-to-X (also P2X and P2Y and P2Z) is a number of electricity conversion, energy storage, and reconversion pathways that use surplus electric power, typically during periods where fluctuating renewable energy generation exceeds load. Power- ...
, that is coupling the electricity sector to the heat and mobility sector via power-to-heat-systems and electric vehicles. Building overcapacity for wind and solar generation can help ensure that enough electricity is produced even during poor weather. In optimal weather, energy generation may have to be curtailed if excess electricity cannot be used or stored. The final demand-supply mismatch may be covered by using dispatchable energy sources such as hydropower, bioenergy, or natural gas. Energy storage helps overcome barriers to intermittent renewable energy. The most commonly used and available storage method is pumped-storage hydroelectricity, which requires locations with large differences in height and access to water. Batteries, especially lithium-ion batteries, are also deployed widely. Batteries typically store electricity for short periods. Costs of utility-scale batteries in the US have fallen by around 70% since 2015, however the cost and low energy density of batteries makes them impractical for the very large energy storage needed to balance inter-seasonal variations in energy production. Pumped hydro storage and
power-to-gas Power-to-gas (often abbreviated P2G) is a technology that uses electric power to produce a gaseous fuel. When using surplus power from wind generation, the concept is sometimes called windgas. Most P2G systems use electrolysis to produce hydrogen ...
(converting electricity to gas and back) with capacity for multi-month usage has been implemented in some locations.


Other low-carbon energy sources


Nuclear power

It is expected that the share of
nuclear power Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced ...
will be increased in order to stay on the "1.5 °C pathway". Nuclear power avoided 2–3% of total global greenhouse gas emissions in 2021. The main advantage of nuclear energy is the ability to deliver large amounts of
base load The base load (also baseload) is the minimum level of demand on an electrical grid over a span of time, for example, one week. This demand can be met by unvarying power plants, dispatchable generation, or by a collection of smaller intermittent e ...
when renewable energy is not available. On the other hand, environmental and
security risk In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with respect to something that humans value (such as health, well-being, wealth, property or the environme ...
s could outweigh the benefits. The construction of new nuclear reactors currently takes about 10 years, substantially longer than scaling up the deployment of wind and solar. The largest drawback of nuclear energy, apart from the security risks, is often considered to be the large construction costs when compared to alternatives of sustainable energy sources whose costs are decreasing. China is building a significant number of new power plants, albeit significantly fewer reactors than originally planned. the cost of extending
nuclear power Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced ...
plant lifetimes is competitive with other electricity generation technologies, including new solar and wind projects. New projects are reported to be highly dependent on public subsidies.


Natural gas for fossil fuel switching


Energy conservation and efficiency

Global
primary energy Primary energy (PE) is an energy form found in nature that has not been subjected to any human engineered conversion process. It is energy contained in raw fuels, and other forms of energy, including waste, received as input to a system. Prim ...
demand exceeded 161,000 TWh in 2018. This refers to electricity, transport and heating including all losses. In transport and electricity production, fossil fuel usage has a low efficiency of less than 50%. Large amounts of heat in power plants and in motors of vehicles are wasted. The actual amount of energy consumed is significantly lower at 116,000 TWh. Energy conservation is the effort made to reduce the consumption of energy by using less of an energy service. This can be achieved either by using energy more efficiently (using less energy for a constant service) or by reducing the amount of service used (for example, by driving less). Energy conservation is at the top of the sustainable
energy hierarchy The Energy Hierarchy is a classification of energy options, prioritised to assist progress towards a more sustainable energy system. It is a similar approach to the waste hierarchy for minimising resource depletion, and adopts a parallel sequenc ...
. Energy can be conserved by reducing wastage and losses, improving efficiency through technological upgrades, and improved operations and maintenance. Efficient energy use, sometimes simply called energy efficiency, is the process of reducing the amount of energy required to provide products and services. Improved energy efficiency in buildings ("green buildings"), industrial processes and
transportation Transport (in British English), or transportation (in American English), is the intentional movement of humans, animals, and goods from one location to another. Modes of transport include air, land (rail and road), water, cable, pipeline, ...
could reduce the world's energy needs in 2050 by one third, and thus help reduce global emissions of greenhouse gases. For example, insulating a building allows it to use less heating and cooling energy to achieve and maintain
thermal comfort Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation ( ANSI/ASHRAE Standard 55).ANSI/ASHRAE Standard 55-2017, Thermal Environmental Conditions for Human Occupan ...
. Improvements in energy efficiency are generally achieved by adopting a more efficient technology or production process or by application of commonly accepted methods to reduce energy losses.


Mitigation by sector


Buildings

The buildings sector accounts for 23% of global energy-related emissions.Rogelj, J., D. Shindell, K. Jiang, S. Fifita, P. Forster, V. Ginzburg, C. Handa, H. Kheshgi, S. Kobayashi, E. Kriegler, L. Mundaca, R. Séférian, and M.V.Vilariño, 2018
Chapter 2: Mitigation Pathways Compatible with 1.5°C in the Context of Sustainable Development
In
Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty
[Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 93-174. https://doi.org/10.1017/9781009157940.004.
About half of the energy is used for space and water heating. Building insulation can reduce the primary energy demand significantly. Efficient
electric heating Electric heating is a process in which electrical energy is converted directly to heat energy at around 100% efficiency, using rather cheap devices. Common applications include space heating, cooking, water heating and industrial processes. ...
and cooling loads may also provide a flexible resource that can participate in demand response to integrate variable renewable resources into the grid.
Solar water heating Solar water heating (SWH) is heating water by sunlight, using a solar thermal collector. A variety of configurations are available at varying cost to provide solutions in different climates and latitudes. SWHs are widely used for residential a ...
uses the thermal energy directly. Sufficiency measures include moving to smaller houses when the needs of households change, mixed use of spaces and the collective use of devices. New buildings can be constructed using
passive solar building design In passive solar building design, windows, walls, and floors are made to collect, store, reflect, and distribute solar energy, in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design because, unli ...
,
low-energy building A low-energy house is characterized by an energy-efficient design and technical features which enable it to provide high living standards and comfort with low energy consumption and carbon emissions. Traditional heating and active cooling systems ...
, or
zero-energy building A Zero Energy Building (ZEB), also known as a Net Zero Energy (NZE) building, is a building with net zero energy consumption, meaning the total amount of energy used by the building on an annual basis is equal to the amount of renewable energy ...
techniques.In addition, it is possible to design buildings that are more energy-efficient to cool by using lighter-coloured, more reflective materials in the development of urban areas.
Heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing ...
s are an example of electrified heating with high efficiency. A modern heat pump typically produces around three to five times more thermal energy than electrical energy consumed, depending on the
coefficient of performance The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required. Higher COPs equate to higher efficiency, lower energy ( ...
and the outside temperature. It uses an electrically driven compressor that extracts heat energy from outdoor air or ground sources and moves that heat to the space to be warmed. In the summer months, the cycle can be reversed for
air conditioning Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
.
Refrigeration The term refrigeration refers to the process of removing heat from an enclosed space or substance for the purpose of lowering the temperature.International Dictionary of Refrigeration, http://dictionary.iifiir.org/search.phpASHRAE Terminology, ht ...
and
air conditioning Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
account for about 10% of global emissions caused by fossil fuel-based energy production and the use of fluorinated gases. Alternative cooling systems, such as passive cooling building design and installing
passive daytime radiative cooling Passive daytime radiative cooling (PDRC) is a renewable cooling method proposed as a solution to global warming of enhancing terrestrial heat flow to outer space through the installation of thermally-emissive surfaces on Earth that require zer ...
surfaces, can reduce air conditioning use. Suburbs and cities in hot and arid climates can significantly reduce energy consumption from cooling with daytime radiative cooling. The energy consumption for cooling is expected to rise significantly due to increasing heat and availability of devices in poorer countries. Of the 2.8 billion people living in the hottest parts of the world, only 8% currently have air conditioners, compared with 90% of people in the US and Japan. By combining energy efficiency improvements with the transition away from super-polluting refrigerants, the world could avoid cumulative greenhouse gas emissions of up to 210–460 Gte over the next four decades. A shift to renewable energy in the cooling sector comes with two advantages: Solar energy production with mid-day peaks corresponds with the load required for cooling. Additionally, cooling has a large potential for load management in the electric grid.


Transport

Transportation emissions account for 15% of emissions worldwide. Increasing the use of
public transport Public transport (also known as public transportation, public transit, mass transit, or simply transit) is a system of transport for passengers by group travel systems available for use by the general public unlike private transport, typi ...
, low-carbon freight transport and
cycling Cycling, also, when on a two-wheeled bicycle, called bicycling or biking, is the use of cycles for transport, recreation, exercise or sport. People engaged in cycling are referred to as "cyclists", "bicyclists", or "bikers". Apart from t ...
are important components of transport decarbonization. Electric vehicles and environmentally friendly rail help to reduce the consumption of fossil fuels. In most cases, electric trains are more efficient than air transport and truck transport. Other efficiency means include improved public transport,
smart mobility Smart mobility refers to many Mode of transport, modes of transport. Some smart mobility services include: * public transport (with real-time timetabling and route optimization, seamless travel and digital ticketing) * Carsharing * Mobility as a s ...
, carsharing and electric hybrids. Fossil-fuel powered passenger cars can be converted to electric propulsion. Furthermore, moving away from a car-dominated transport system towards low-carbon advanced public transport system is important. Heavyweight, large personal vehicles (such as cars) require a lot of energy to move and take up much urban space. Several alternatives modes of transport are available to replace these. The
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
has made smart mobility part of its European Green Deal and in
smart cities A smart city is a technologically modern urban area that uses different types of electronic methods and sensors to collect specific data. Information gained from that data is used to manage assets, resources and services efficiently; in retur ...
, smart mobility is also important. The
World Bank The World Bank is an international financial institution that provides loans and grants to the governments of low- and middle-income countries for the purpose of pursuing capital projects. The World Bank is the collective name for the Inte ...
is supporting lower income countries to buy
electric bus An electric bus is a bus that is propelled using electric motors as opposed to an internal combustion engine. Electric buses can store the needed electricity on-board, or be fed continuously from an external source. The majority of buses ...
es, as although their purchase price is higher than diesel buses this can be offset through lower running costs, and health improvements due to cleaner air in cities. Between a quarter and three-quarters of cars on the road by 2050 are forecast to be electric vehicles.
Hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
may be a solution for long-distance heavy freight trucks, if batteries alone are too heavy.


Shipping

In the shipping industry, the use of
liquefied natural gas Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled down to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the vol ...
(LNG) as a marine bunker fuel is driven by emissions regulations. Ship operators have to switch from
heavy fuel oil Heavy Fuel Oil (HFO) is a category of fuel oils of a tar-like consistency. Also known as bunker fuel, or residual fuel oil, HFO is the result or remnant from the distillation and cracking process of petroleum. For this reason, HFO is contaminate ...
to more expensive oil-based fuels, implement costly flue gas treatment technologies or switch to LNG engines. Methane slip, when gas leaks unburned through the engine, lowers the advantages of LNG.
Maersk (), also known simply as Maersk (), is a Danish shipping company, active in ocean and inland freight transportation and associated services, such as supply chain management and port operation. Maersk was the largest container shipping line a ...
, the largest container shipping line and vessel operator in the world, warns of
stranded asset Stranded assets are "assets that have suffered from unanticipated or premature write-downs, devaluations or conversion to liabilities". Stranded assets can be caused by a variety of factors and are a phenomenon inherent in the 'creative destructi ...
s when investing into transitional fuels like LNG. The company lists green
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
as one of the preferred fuel types of the future and has announced the first carbon-neutral vessel on the water by 2023, running on carbon-neutral methanol. Partially hydrogen-powered ships are being trialled for cruises. Hybrid and all electric ferries are suitable for short distances. Norway's goal is an all electric fleet by 2025. The E-ferry Ellen, which was developed in an EU-backed project, is in operation in Denmark.


Air transport

Jet airliners contribute to
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
by emitting
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
(), the best understood greenhouse gas, and, with less scientific understanding,
nitrogen oxides Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds: Charge-neutral *Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide *Nitrogen dioxide (), nitrogen(IV) oxide * Nitrogen trioxide (), or ...
,
contrails Contrails (; short for "condensation trails") or vapor trails are line-shaped clouds produced by aircraft engine exhaust or changes in air pressure, typically at aircraft cruising altitudes several miles above the Earth's surface. Contrails a ...
and particulates. Their
radiative forcing Radiative forcing (or climate forcing) is the change in energy flux in the atmosphere caused by natural or anthropogenic factors of climate change as measured by watts / metre2. It is a scientific concept used to quantify and compare the extern ...
is estimated at 1.3–1.4 that of alone, excluding induced
cirrus cloud Cirrus ( cloud classification symbol: Ci) is a genus of high cloud made of ice crystals. Cirrus clouds typically appear delicate and wispy with white strands. Cirrus are usually formed when warm, dry air rises, causing water vapor deposition on ...
with a very low level of scientific understanding. In 2018, global commercial operations generated 2.4% of all emissions. While the
aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot a ...
industry has become more
fuel efficient Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
, overall emissions have risen as the volume of
air travel Air travel is a form of travel in vehicles such as airplanes, jet aircraft, helicopters, hot air balloons, blimps, gliders, hang gliders, parachutes, or anything else that can sustain flight.
has increased. By 2020, aviation emissions were 70% higher than in 2005 and they could grow by 300% by 2050. Aviation's environmental footprint can be reduced by better
fuel economy in aircraft The fuel economy in aircraft is the measure of the transport energy efficiency of aircraft. Efficiency is increased with better aerodynamics and by reducing weight, and with improved engine BSFC and propulsive efficiency or TSFC. Endura ...
, and by optimising flight routes to lower non- effects on climate from , particulates or contrails.
Aviation biofuel An aviation biofuel or bio-jet fuel Note: About">Investable Universe>About' or bio-aviation fuel (BAF) is a biofuel used to power aircraft and is said to be a sustainable aviation fuel (SAF). The International Air Transport Association (IATA) co ...
,
emissions trading Emissions trading is a market-based approach to controlling pollution by providing economic incentives for reducing the emissions of pollutants. The concept is also known as cap and trade (CAT) or emissions trading scheme (ETS). Carbon emission ...
and
carbon offsetting A carbon offset is a reduction or removal of emissions of carbon dioxide or other greenhouse gases made in order to compensate for emissions made elsewhere. Offsets are measured in tonnes of carbon dioxide-equivalent (CO2e). One ton of carbo ...
, part of the 191 nation ICAO's Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), can lower emissions. Aviation usage can be lowered by short-haul flight bans, train connections, personal choices and taxation on flights. Fuel-powered aircraft may be replaced by
hybrid electric aircraft A hybrid electric aircraft is an aircraft with a hybrid electric powertrain. As the energy density of lithium-ion batteries is much lower than aviation fuel, a hybrid electric powertrain may effectively increase flight range compared to pure electr ...
and electric aircraft or by
hydrogen-powered aircraft A hydrogen-powered aircraft is an aeroplane that uses hydrogen fuel as a power source. Hydrogen can either be burned in a jet engine or another kind of internal combustion engine, or can be used to power a fuel cell to generate electricity to powe ...
. In aviation, current 180 Mt of emissions (11% of emissions in transport) are expected to rise in most projections, at least until 2040.
Aviation biofuel An aviation biofuel or bio-jet fuel Note: About">Investable Universe>About' or bio-aviation fuel (BAF) is a biofuel used to power aircraft and is said to be a sustainable aviation fuel (SAF). The International Air Transport Association (IATA) co ...
and hydrogen can only cover a small proportion of flights in the coming years. The market entry for hybrid-driven aircraft on regional scheduled flights is projected after 2030, for battery-powered aircraft after 2035. Under CORSIA flight operators can purchase
carbon offset A carbon offset is a reduction or removal of emissions of carbon dioxide or other greenhouse gases made in order to compensate for emissions made elsewhere. Offsets are measured in tonnes of carbon dioxide-equivalent (CO2e). One ton of carb ...
s to cover their emissions above 2019 levels, CORSIA will be compulsory from 2027.


Agriculture, forestry and land use

Almost 20% of greenhouse gas emissions come from the agriculture and forestry sector. Mitigation measures in the food system can be divided into four categories: demand-side changes, ecosystem protections, mitigation on farms, and mitigation in the supply chains. On the demand side, limiting
food waste Food loss and waste is food that is not eaten. The causes of food waste or loss are numerous and occur throughout the food system, during production, processing, distribution, retail and food service sales, and consumption. Overall, about o ...
is an effective way to reduce food emissions. Furthermore, changes to a diet less reliant on animal products (especially plant-based diets), are effective. With 21% of global methane emissions, cattle are a major driver of global warming.Olivier J.G.J. and Peters J.A.H.W. (2020)
Trends in global CO2 and total greenhouse gas emissions: 2020 reportPBL Netherlands
Environmental Assessment Agency, The Hague.
When rainforests are cut and the land is converted for grazing, the impact is even higher. This results in up to 335 kg CO2eq emissions to produce 1 kg beef in Brazil, when using a 30-year time horizon. Other livestock, manure management and rice cultivation also emit greenhouse gases, in addition to fossil fuel combustion in agriculture. Important mitigation options for reducing the greenhouse gas emissions from livestock include genetic selection, introduction of methanotrophic bacteria into the rumen, vaccines, feeds, toilet-training, diet modification and grazing management. Other options include just using
ruminant Ruminants (suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...
-free alternatives instead, such as
milk substitute A milk substitute is any substance that resembles milk and can be used in the same ways as milk. Such substances may be variously known as non-dairy beverage, nut milk, grain milk, legume milk, mock milk and alternative milk. For adults, milk ...
s and
meat analogue A meat alternative or meat substitute (also called plant-based meat or fake meat, sometimes pejoratively) is a food product made from vegetarian or vegan ingredients, eaten as a replacement for meat. Meat alternatives typically approximate qua ...
s. Non-ruminant livestock, such as poultry, emits far less. Methane emissions in rice cultivation can be cut by implementing an improved water management, combining dry seeding and one drawdown, or a perfect execution of a sequence of wetting and drying. This results in emission reductions of up to 90% compared to full flooding and even increased yields.


Industry

Bioconcrete is one possibility to reduce emissions from cement production, but because no technology for mitigation is mature yet CCS will be needed at least in the short-term. Blast furnaces could be replaced by hydrogen
direct reduced iron Direct reduced iron (DRI), also called sponge iron, is produced from the direct reduction of iron ore (in the form of lumps, pellets, or fines) into iron by a reducing gas or elemental carbon produced from natural gas or coal. Many ores are suit ...
and
electric arc furnace An electric arc furnace (EAF) is a furnace that heats material by means of an electric arc. Industrial arc furnaces range in size from small units of approximately one-tonne capacity (used in foundries for producing cast iron products) up to ...
s.


Methane leaks

In 2021 a similar amount of methane leaked from the coal, oil and gas sectors. In the early 2020s some governments recognized the scale of the problem and introduced regulations.
Methane leaks Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane ...
at oil and gas wells and processing plants are cost-effective to fix in countries which can easily trade gas internationally. There are leaks in countries where gas is cheap; such as
Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
,
Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...
, and
Turkmenistan Turkmenistan ( or ; tk, Türkmenistan / Түркменистан, ) is a country located in Central Asia, bordered by Kazakhstan to the northwest, Uzbekistan to the north, east and northeast, Afghanistan to the southeast, Iran to the sout ...
.
Gas flare A gas flare, alternatively known as a flare stack, flare boom, ground flare, or flare pit is a gas combustion device used in places such as petroleum refineries, chemical plants and natural gas processing plants, oil or gas extraction sites ha ...
s do not always burn all the methane. Nearly all this can be stopped by replacing old components and preventing routine flaring. However the IEA said in 2021 that "state-owned firms may not directly benefit from cost-saving measures because they return earnings to the government treasury, and then receive pre‑determined appropriations to cover operations". neither Russia, Turkmenistan nor Iran have joined the global methane pledge to reduce leaks from oil and gas by at least 30%. Coalbed methane may continue leaking even after the mine has been closed, but it can be captured by drainage and/or ventilation systems.


Wastewater and solid waste

Methane emissions from
municipal solid waste Municipal solid waste (MSW), commonly known as trash or garbage in the United States and rubbish in Britain, is a waste type consisting of everyday items that are discarded by the public. "Garbage" can also refer specifically to food waste ...
can be reduced by segregation, composting, and recycling. Solutions exist to reduce the greenhouse gas emissions of water and sanitation services. These solutions can be grouped in three categories: Firstly "reducing water and energy consumption through lean and efficient approaches"; secondly "embracing circular economy to produce energy and valuable products"; and thirdly by "planning to reduce GHG emissions through strategic decisions".


Preserving and enhancing carbon sinks

To reduce pressures on ecosystems and enhance their carbon sequestration capabilities, changes would also be necessary in agriculture and forestry, such as preventing
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
and restoring natural ecosystems by
reforestation Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting. Management A debat ...
. Scenarios that limit global warming to 1.5 °C typically project the large-scale use of carbon dioxide removal methods over the 21st century.IPCC, 2018
Summary for Policymakers
In
Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty
[Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 3-24. https://doi.org/10.1017/9781009157940.001.
There are concerns though about over-reliance on these technologies, and environmental impacts. Carbon dioxide removal (CDR) is defined as "Anthropogenic activities removing carbon dioxide () from the atmosphere and durably storing it in geological, terrestrial, or ocean reservoirs, or in products. It includes existing and potential anthropogenic enhancement of biological or geochemical sinks and direct air carbon dioxide capture and storage (DACCS), but excludes natural uptake not directly caused by human activities." The terminology in this area is still evolving. The term "geoengineering" (or
climate engineering Climate engineering (also called geoengineering) is a term used for both carbon dioxide removal (CDR) and solar radiation management (SRM), also called solar geoengineering, when applied at a planetary scale.IPCC (2022Chapter 1: Introduction and ...
) is sometimes used in the scientific literature for both CDR (carbon dioxide removal) or SRM (solar radiation management or
solar geoengineering Solar geoengineering, or solar radiation modification (SRM), is a type of climate engineering in which sunlight (solar radiation) would be reflected back to outer space to limit or reverse human-caused climate change. It is not a substitute for ...
), if the techniques are used at a global scale.IPCC (2022
Chapter 1: Introduction and Framing
i
Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
The terms geoengineering or climate engineering are no longer used in IPCC reports. Land-based mitigation options are referred to as "AFOLU mitigation options" in the 2022 IPCC report on mitigation. The abbreviation stands for "agriculture, forestry and other land use" The report described the economic mitigation potential from relevant activities around forests and ecosystems as follows: "the conservation, improved management, and restoration of forests and other ecosystems (coastal wetlands,
peatlands A mire, peatland, or quagmire is a wetland area dominated by living peat-forming plants. Mires arise because of incomplete decomposition of organic matter, usually litter from vegetation, due to water-logging and subsequent anoxia. All types ...
, savannas and grasslands)". A high mitigation potential is found for reducing
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
in tropical regions. The economic potential of these activities has been estimated to be 4.2 to 7.4 Giga tons of CO2 equivalents per year.


Forests

Mitigation measures in the area of forestry are slow and often have trade-offs with food prices and potential confounding spill-over effects on climate from indirect land use change.


Conservation

About 95% of deforestation occurs in the tropics, where it is mostly driven by the clearing of land for agriculture. One forest conservation strategy is transferring rights over land from public domain to its indigenous inhabitants. Concessions to land often go to powerful extractive companies and conservation strategies that exclude and even evict humans, called " fortress conservation", often lead to more exploitation of the land as the native inhabitants then turn to work for extractive companies to survive.


Afforestation and reforestation

Afforestation is the establishment of trees where there was previously no tree cover. Scenarios for new plantations covering up to 4000 Mha (6300 x 6300 km) calculate with a cumulative physical carbon
biosequestration Biosequestration or biological sequestration is the capture and storage of the atmospheric greenhouse gas carbon dioxide by continual or enhanced biological processes. This form of carbon sequestration occurs through increased rates of photosyn ...
of more than 900 GtC (2300 Gt) until 2100. However, these are not considered a viable alternative to aggressive emissions reduction, as the plantations would need to be so large, they would eliminate most natural ecosystems or reduce food production. One example is the Trillion Tree Campaign.
Reforestation Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting. Management A debat ...
is the restocking of existing depleted forests or where there was once recently forests. Reforestation could save at least 1GtCO2/year, at an estimated cost of $5–15/tCO2.Stern, N. (2006). ''Stern Review on the Economics of Climate Change: Part III: The Economics of Stabilisation.'' HM Treasury, London: http://hm-treasury.gov.uk/sternreview_index.htm Restoring all degraded forests all over the world could capture about 205 GtC (750 Gt). With increased
intensive agriculture Intensive agriculture, also known as intensive farming (as opposed to extensive farming), conventional, or industrial agriculture, is a type of agriculture, both of crop plants and of animals, with higher levels of input and output per unit of ag ...
and
urbanization Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly t ...
, there is an increase in the amount of abandoned farmland. By some estimates, for every acre of original old-growth forest cut down, more than 50 acres of new secondary forests are growing. Promoting regrowth on abandoned farmland could offset years of carbon emissions. Planting new trees can be expensive and a risky investment as, for example, about 80 percent of planted trees in the Sahel die within two years. Instead, helping native species sprout naturally is cheaper and they are more likely to survive, with even long deforested areas still containing an "underground forest" of living roots and tree stumps. This could include
pruning Pruning is a horticultural, arboricultural, and silvicultural practice involving the selective removal of certain parts of a plant, such as branches, buds, or roots. The practice entails the ''targeted'' removal of diseased, damaged, dead, ...
and
coppicing Coppicing is a traditional method of woodland management which exploits the capacity of many species of trees to put out new shoots from their stump or roots if cut down. In a coppiced wood, which is called a copse, young tree stems are repeate ...
to accelerate growth and this also provides woodfuel, which is otherwise a major source of deforestation. Such practices, called
farmer-managed natural regeneration Farmer-managed natural regeneration (FMNR) is a low-cost, sustainable land restoration technique used to combat poverty and hunger amongst poor subsistence farmers in developing countries by increasing food and timber production, and resilience ...
, are centuries old but the biggest obstacle towards implementation is the ownership of the trees by the state, who often sell timber rights to businesses. This leads to seedlings being uprooted by locals who saw them as a liability. Legal aid for locals and changes to property law such as in
Mali Mali (; ), officially the Republic of Mali,, , ff, 𞤈𞤫𞤲𞥆𞤣𞤢𞥄𞤲𞤣𞤭 𞤃𞤢𞥄𞤤𞤭, Renndaandi Maali, italics=no, ar, جمهورية مالي, Jumhūriyyāt Mālī is a landlocked country in West Africa. Mal ...
and
Niger ) , official_languages = , languages_type = National languagesNigeria Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf o ...
, where the law has not changed. Proforestation is promoting forests to capture their full ecological potential. This is a mitigation strategy as secondary forests that have regrown in abandoned farmland are found to have less biodiversity than the original old-growth forests and original forests store 60% more carbon than these new forests. Strategies include
rewilding Rewilding may refer to: *Rewilding (conservation biology), the return of habitats to a natural state **Rewilding Europe Rewilding Europe is a non-profit organisation based in Nijmegen, Netherlands, working to create rewilded landscapes through ...
and establishing
wildlife corridor A wildlife corridor, habitat corridor, or green corridor is an area of habitat connecting wildlife populations separated by human activities or structures (such as roads, development, or logging). This allows an exchange of individuals between ...
s.


Increasing soil carbon

There are lots of different measures in the group of "increasing soil carbon", which makes it complex and hard to measure and account for; an advantage is that there are fewer trade-offs for these measures than for BECCS or afforestation, for example. Globally, protecting healthy soils and restoring the soil carbon sponge could remove 7.6 billion tons of carbon dioxide from the atmosphere annually, which is more than the annual emissions of the US. Trees capture while growing above ground and exuding larger amounts of carbon below ground. Trees contribute to the building of a
soil carbon sponge Soil carbon sponge (or soil sponge) is porous, well-aggregated soil in good health, better able to absorb and retain water. Australian microbiologist and climatologist, Walter Jehne, articulated the concept of the soil carbon sponge in his 2017 ...
. The carbon formed above ground is released as immediately when wood is burned. If dead wood remains untouched, only some of the carbon returns to the atmosphere as decomposition proceeds. Methods that enhance carbon sequestration in soil include
no-till farming No-till farming (also known as zero tillage or direct drilling) is an agricultural technique for growing crops or pasture without disturbing the soil through tillage. No-till farming decreases the amount of soil erosion tillage causes in certai ...
, residue mulching and
crop rotation Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant ...
, all of which are more widely used in
organic farming Organic farming, also known as ecological farming or biological farming,Labelling, article 30 o''Regulation (EU) 2018/848 of the European Parliament and of the Council of 30 May 2018 on organic production and labelling of organic products and re ...
than in conventional farming. Because only 5% of US farmland currently uses no-till and residue mulching, there is a large potential for carbon sequestration. Farming can deplete soil carbon and render soil incapable of supporting life. However, conservation farming can protect carbon in soils, and repair damage over time. The farming practice of cover crops has been recognized as
climate-smart agriculture Climate-smart agriculture (CSA) (or climate resilient agriculture) is an integrated approach to managing landscapes to help adapt agricultural methods, livestock and crops to the effects of climate change and, where possible, counteract it by red ...
. Best management practices for European soils were described to increase soil organic carbon: conversion of arable land to grassland, straw incorporation, reduced tillage, straw incorporation combined with reduced tillage, ley cropping system and cover crops.
Regenerative agriculture Regenerative agriculture is a conservation and rehabilitation approach to food and farming systems. It focuses on topsoil regeneration, increasing biodiversity, improving the water cycle, enhancing ecosystem services, supporting biosequestration, ...
includes conservation tillage, diversity, rotation and cover crops, minimizing physical disturbance and supporting
biosequestration Biosequestration or biological sequestration is the capture and storage of the atmospheric greenhouse gas carbon dioxide by continual or enhanced biological processes. This form of carbon sequestration occurs through increased rates of photosyn ...
. It has other benefits like improving the state of the soil and consequently yields.


Biochar

Biochar Biochar is the lightweight black residue, made of carbon and ashes, remaining after the pyrolysis of biomass. Biochar is defined by the International Biochar Initiative as "the solid material obtained from the thermochemical conversion of ...
is the lightweight black residue, made of
carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
and ashes, remaining after the
pyrolysis The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''py ...
of biomass. Biochar is a stable solid that is rich in pyrogenic
carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
and can endure in soil for thousands of years. The
refractory In materials science, a refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, ...
stability of biochar leads to the concept of
pyrogenic carbon capture and storage Pyrogenic carbon capture and storage (PyCCS) is a proposed carbon sequestration technology that can mitigate climate change while improving soil fertility. It is discussed as a promising technology for greenhouse gas removal.Constanze Werner et ...
(PyCCS), i.e.
carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in lan ...
in the form of biochar. It may be a means to mitigate climate change. Biochar may increase the soil fertility of
acidic soil Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the n ...
s and increase
agricultural productivity Agricultural productivity is measured as the ratio of agricultural outputs to inputs. While individual products are usually measured by weight, which is known as crop yield, varying products make measuring overall agricultural output difficu ...
. Biomass burning and natural decomposition releases large amounts of
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
and
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
to the Earth's atmosphere. The biochar production process also releases (up to 50% of the biomass), however, the remaining carbon content becomes indefinitely stable. Biochar carbon remains in the ground for centuries, slowing the growth in atmospheric greenhouse gas levels.


Wetland restoration

Wetland restoration is an important mitigation measure which has moderate to big mitigation potential on a limited land area with low trade-offs and costs. Wetlands perform two important functions in relation to
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
. They have mitigation effects through their ability to sink carbon, converting a greenhouse gas (
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
) to solid plant material through the process of
photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
, and also through their ability to store and regulate water. Wetlands store approximately 44.6 million tonnes of carbon per year globally.
Wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The p ...
s such as swamps and
peatlands A mire, peatland, or quagmire is a wetland area dominated by living peat-forming plants. Mires arise because of incomplete decomposition of organic matter, usually litter from vegetation, due to water-logging and subsequent anoxia. All types ...
have lower oxygen levels dissolved than in the air and so oxygen reliant decomposition of organic matter by microbes into is decreased. Depending on their characteristics, some wetlands are a significant source of methane emissions and some are also emitters of
nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...
.
Mangrove A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...
s,
salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is domin ...
es and
seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the or ...
es make up the majority of the ocean's vegetated habitats but only equal 0.05% of the plant biomass on land and stash carbon 40 times faster than tropical forests.
Bottom trawling Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is towing ...
, dredging for coastal development and fertilizer runoff have damaged coastal habitats. Notably, 85% of
oyster reef The term ''oyster reef'' refers to dense aggregations of oysters that form large colonial communities. Because oyster larvae need to settle on hard substrates, new oyster reefs may form on stone or other hard marine debris. Eventually the oyster ...
s globally have been removed in the last two centuries. Oyster reefs clean the water and make other species thrive, thus increasing biomass in that area. In addition, oyster reefs mitigate the effects of climate change by reducing the force of waves from hurricanes and reduce the erosion from rising sea levels. Restoration of coastal wetlands is thought to be more cost-effective than restoration of inland wetlands.


Peatlands

Peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficient ...
land globally covers just 3% of the land's surface but stores up to 550 gigatonnes of carbon, representing 42% of all soil carbon and exceeds the carbon stored in all other vegetation types, including the world's forests. The threat to peatlands include draining the areas for agriculture and cutting down trees for lumber as the trees help hold and fix the peatland. Additionally, peat is often sold for compost. Restoration of degraded peatlands can be done by blocking drainage channels in the peatland, and allowing natural vegetation to recover.


Bioenergy with carbon capture and storage

Bioenergy with carbon capture and storage Bioenergy with carbon capture and storage (BECCS) is the process of extracting bioenergy from biomass and capturing and storing the carbon, thereby removing it from the atmosphere. The carbon in the biomass comes from the greenhouse gas carbo ...
(BECCS) is the process of extracting bioenergy from biomass and capturing and storing the carbon, thereby removing it from the atmosphere. The carbon in the biomass comes from the greenhouse gas
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
(CO2) which is extracted from the atmosphere by the biomass when it grows. Energy is extracted in useful forms (electricity, heat, biofuels, etc.) as the biomass is utilized through combustion, fermentation, pyrolysis or other conversion methods. Some of the carbon in the biomass is converted to CO2 or
biochar Biochar is the lightweight black residue, made of carbon and ashes, remaining after the pyrolysis of biomass. Biochar is defined by the International Biochar Initiative as "the solid material obtained from the thermochemical conversion of ...
which can then be stored by geologic sequestration or land application, respectively, enabling
carbon dioxide removal Carbon dioxide removal (CDR), also known as negative emissions, is a process in which carbon dioxide gas () is removed from the atmosphere and sequestered for long periods of time. Similarly, greenhouse gas removal (GGR) or negative greenho ...
(CDR) and making BECCS a negative emissions technology (NET). The potential range of negative emissions from BECCS was estimated in 2018 as 0 to 22
giga Giga ( or ) is a unit prefix in the metric system denoting a factor of a short-scale billion or long-scale milliard (109 or ). It has the symbol G. ''Giga'' is derived from the Greek word (''gígas''), meaning "giant". The ''Oxford English Dic ...
tonnes The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton (United States c ...
per year. , approximately 2 million tonnes per year of CO2 was being captured annually. Wide deployment of BECCS is constrained by cost and availability of biomass. BECCS currently forms a big part of achieving climate targets beyond 2050 in modelling, such as by the Integrated Assessment Models (IAMs) associated with the IPCC process, but many scientists are very skeptical due the risk of loss of biodiversity and increases in food prices.


Ocean-based options

In principle, carbon can be stored in ocean reservoirs. This can be done with "ocean-based mitigation systems" including
ocean fertilization Ocean fertilization or ocean nourishment is a type of technology for carbon dioxide removal from the ocean based on the purposeful introduction of plant nutrients to the upper ocean to increase marine food production and to remove carbon dioxid ...
, ocean alkalinity enhancement or
enhanced weathering Enhanced weathering is a process that aims to accelerate the natural weathering by spreading finely ground silicate rock, such as basalt, onto surfaces which speeds up chemical reactions between rocks, water, and air. It also removes carbon dioxi ...
. Blue carbon management is partly an ocean-based method and partly a land-based method.IPCC (2022
Chapter 12: Cross sectoral perspectives
i
Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
Most of these options could also help to reduce
ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
, the drop in pH value caused by increased atmospheric CO2 concentrations. The current assessment of potential for ocean-based mitigation options is in 2022 that they have only "limited current deployment", but "moderate to large future mitigation potentials" in future. In total, "ocean-based methods have a combined potential to remove 1–100 gigatons of per year". Their costs are in the order of USD40–500 per ton of . For example,
enhanced weathering Enhanced weathering is a process that aims to accelerate the natural weathering by spreading finely ground silicate rock, such as basalt, onto surfaces which speeds up chemical reactions between rocks, water, and air. It also removes carbon dioxi ...
could remove 2–4 gigatons of per year. This technology comes with a cost of 50-200 USD per ton of . Enhanced weathering is a process that aims to accelerate the natural
weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement) ...
by spreading finely ground silicate rock, such as
basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...
, onto surfaces which speeds up chemical reactions between rocks, water, and air. It removes removes carbon dioxide () from the atmosphere, permanently storing it in solid
carbonate mineral Carbonate minerals are those minerals containing the carbonate ion, . Carbonate divisions Anhydrous carbonates *Calcite group: trigonal ** Calcite CaCO3 ** Gaspéite (Ni,Mg,Fe2+)CO3 ** Magnesite MgCO3 ** Otavite CdCO3 **Rhodochrosite MnCO3 ** ...
s or ocean
alkalinity Alkalinity (from ar, القلوي, al-qaly, lit=ashes of the saltwort) is the capacity of water to resist acidification. It should not be confused with basicity, which is an absolute measurement on the pH scale. Alkalinity is the strength ...
.


Technologies to capture carbon dioxide

*
Direct air capture Direct air capture (DAC) is a process of capturing carbon dioxide () directly from the ambient air (as opposed to capturing from point sources, such as a cement factory or biomass power plant) and generating a concentrated stream of for seque ...
is a process of capturing directly from the ambient air (as opposed to capturing from point sources) and generating a concentrated stream of for sequestration or utilization or production of
carbon-neutral fuel Carbon-neutral fuel is fuel which produces no net-greenhouse gas emissions or carbon footprint. In practice, this usually means fuels that are made using carbon dioxide (CO2) as a feedstock. Proposed carbon-neutral fuels can broadly be grouped ...
and windgas. Artificial processes vary, and concerns have been expressed about the long-term effects of some of these processes.The Royal Society, (2009
"Geoengineering the climate: science, governance and uncertainty"
Retrieved 12 September 2009.
*
Carbon capture and storage Carbon capture and storage (CCS) or carbon capture and sequestration is the process of capturing carbon dioxide (CO2) before it enters the atmosphere, transporting it, and storing it (carbon sequestration) for centuries or millennia. Usually th ...
(CCS) is a method to mitigate climate change by capturing
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
(CO2) from large point sources, such as cement factories or biomass power plants, and subsequently storing it away safely instead of releasing it into the atmosphere. The IPCC estimates that the costs of halting global warming would double without CCS. Norway's
Sleipner gas field Oil from the Sleipner field. The Sleipner gas field is a natural gas field in the block 15/9 of the North Sea, about west of Stavanger, Norway. Two parts of the field are in production, Sleipner West (proven in 1974), and Sleipner East (1981) ...
, beginning in 1996, stores almost a million tons of CO2 a year to avoid penalties in producing natural gas with unusually high levels of CO2.


Demand reduction

The
IPCC Sixth Assessment Report The Sixth Assessment Report (AR6) of the United Nations (UN) Intergovernmental Panel on Climate Change (IPCC) is the sixth in a series of reports which assess scientific, technical, and socio-economic information concerning climate change. Three ...
pointed out in 2022: "To enhance well-being, people demand services and not
primary energy Primary energy (PE) is an energy form found in nature that has not been subjected to any human engineered conversion process. It is energy contained in raw fuels, and other forms of energy, including waste, received as input to a system. Prim ...
and physical
resource Resource refers to all the materials available in our environment which are technologically accessible, economically feasible and culturally sustainable and help us to satisfy our needs and wants. Resources can broadly be classified upon their ...
s per se. Focusing on demand for services and the different social and political roles people play broadens the participation in climate action." The report explains that behavior,
lifestyle Lifestyle often refers to: * Lifestyle (sociology), the way a person lives * ''Otium'', ancient Roman concept of a lifestyle * Style of life (german: Lebensstil, link=no), dealing with the dynamics of personality Lifestyle may also refer to: Bu ...
, and cultural change have a high mitigation potential in some sectors, particularly when complementing technological and structural change.Patrick Devine-Wright, Julio Diaz-José, Frank Geels, Arnulf Grubler, Nadia Maïzi, Eric Masanet, Yacob Mulugetta, Chioma Daisy Onyige-Ebeniro, Patricia E. Perkins, Alessandro Sanches Pereira, Elke Ursula Weber (2022
Chapter 5: Demand, services and social aspects of mitigation
i
Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
Mitigation options that reduce demand for products or services are helping people make personal choices to reduce their carbon footprint, for example in their choice of transport options or their diets. This means there are many social aspects with the demand-side mitigation actions. For example, people with high socio-economic status often contribute more to greenhouse gas emissions than those from a lower socio-economic status. By reducing their emissions and promoting green policies, these people could become "role models of low-carbon lifestyles". However, there are many psychological variables that influence motivation of people to reduce their demand such as
awareness Awareness is the state of being conscious of something. More specifically, it is the ability to directly know and perceive, to feel, or to be cognizant of events. Another definition describes it as a state wherein a subject is aware of some infor ...
and
perceived risk Risk perception is the subjective judgement that people make about the characteristics and severity of a risk. Risk perceptions are different for the real risks since they are affected by a wide range of affective (emotions, feelings, moods, etc.) ...
. Government policies can support or hinder demand-site mitigation options. For example,
public policy Public policy is an institutionalized proposal or a decided set of elements like laws, regulations, guidelines, and actions to solve or address relevant and real-world problems, guided by a conception and often implemented by programs. Public p ...
can promote circular economy concepts which would support climate change mitigation. Reducing greenhouse gas emissions is linked to sharing economy and circular economy. It has been estimated that only 0.12% of all funding for climate-related research is spent on the social science of climate change mitigation. Vastly more funding is spent on natural science studies of climate change and considerable sums are also spent on studies of impact of and adaptation to climate change.


Actions by individuals


Lifestyle changes

Individual action on climate change Individual action on climate change can include personal choices in many areas, such as diet, travel, household energy use, consumption of goods and services, and family size. Individuals can also engage in local and political advocacy around iss ...
can include personal choices in many areas, such as diet, travel, household energy use, consumption of goods and services, and family size. People who wish to reduce their carbon footprint (particularly those in high income countries with high consumption lifestyles), can take "high-impact" actions, such as avoiding frequent flying and petrol fuelled cars, eating mainly a
plant-based diet A plant-based diet is a diet consisting mostly or entirely of plant-based foods. Plant-based diets encompass a wide range of dietary patterns that contain low amounts of animal products and high amounts of plant products such as vegetables, fru ...
, having fewer children, using clothes and electrical products for longer, and electrifying homes. Excessive consumption is more to blame for climate change than
population increase Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to ...
. High consumption lifestyles have a greater environmental impact, with the richest 10% of people emitting about half the total lifestyle emissions.


Dietary change

Avoiding meat and dairy foods has been called "the single biggest way" an individual can reduce their environmental impact. The widespread adoption of a vegetarian diet could cut food-related greenhouse gas emissions by 63% by 2050. China introduced new dietary guidelines in 2016 which aim to cut meat consumption by 50% and thereby reduce greenhouse gas emissions by 1billion tonnes by 2030. Overall, food accounts for the largest share of consumption-based greenhouse gas emissions with nearly 20% of the global carbon footprint. Almost 15% of all anthropogenic greenhouse gas emissions has been attributed to the
livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animal ...
sector. A shift towards plant-based diets would help to mitigate climate change. In particular, reducing meat consumption would help to reduce methane emissions. If high-income nations switched to a plant-based diet, vast amounts of land used for animal agriculture could be allowed to return to their natural state, which in turn has the potential to sequester 100 billion tons of by the end of the century.


Family size

Population growth results in higher greenhouse gas emissions in most regions, particularly Africa.IPCC (2022
Chapter 6: Energy systems
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Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
However, economic growth has a bigger effect than population growth. It is the rising incomes, changes in consumption and dietary patterns, together with population growth, which causes pressure on land and other natural resources, and leads to more greenhouse gas emissions and less carbon sinks.IPCC (2022
Chapter 7: Agriculture, Forestry, and Other Land Uses (AFOLU)
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Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
Scholars have pointed out that "In concert with policies that end fossil fuel use and incentivize sustainable consumption, humane policies that slow population growth should be part of a multifaceted climate response." It is known that "advances in female education and
reproductive health Sexual and reproductive health (SRH) is a field of research, healthcare, and social activism that explores the health of an individual's reproductive system and sexual wellbeing during all stages of their life. The term can also be further de ...
, especially voluntary family planning, can contribute greatly to reducing world population growth".


Investment and finance


Investment

More than 1000 organizations with a worth of US$8 trillion have made commitments to fossil fuel divestment.
Socially responsible investing Socially responsible investing (SRI), social investment, sustainable socially conscious, "green" or ethical investing, is any investment strategy which seeks to consider both financial return and social/environmental good to bring about soci ...
funds allow investors to invest in funds that meet high
environmental, social and corporate governance ESG (environmental, social, and corporate governance) data reflect the negative externalities (costs to others) caused by an organization with respect to the environment, to society and to corporate governance. ESG data can be used by investo ...
(ESG) standards. There are lists to show the business organisations which are the " top contributors to greenhouse gas emissions". Asset management firms are often identified as controllers of large amounts of contemporary financial value with insufficient dedication to climate change targets, with the largest four asset managers controlling around 20% of the world's listed market values – an aggregate assets under management of $20 trillion as of 2021.


Funding

In order to reconcile
economic development In the economics study of the public sector, economic and social development is the process by which the economic well-being and quality of life of a nation, region, local community, or an individual are improved according to targeted goals and ...
with mitigating carbon emissions,
developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
need particular support, both financial and technical. One of the means of achieving this is the Kyoto Protocol's
Clean Development Mechanism The Clean Development Mechanism (CDM) is a United Nations-run carbon offset scheme allowing countries to fund greenhouse gas emissions-reducing projects in other countries and claim the saved emissions as part of their own efforts to meet internat ...
(CDM). The
World Bank The World Bank is an international financial institution that provides loans and grants to the governments of low- and middle-income countries for the purpose of pursuing capital projects. The World Bank is the collective name for the Inte ...
's Prototype Carbon Fund is a
public private partnership In public relations and communication science, publics are groups of individual people, and the public (a.k.a. the general public) is the totality of such groupings. This is a different concept to the sociological concept of the ''Öffentlichkei ...
that operates within the CDM. However, none of these initiatives suggest a quantitative cap on the emissions from developing countries. This is considered as a particularly difficult policy proposal as the economic growth of developing countries are proportionally reflected in the growth of greenhouse emissions. An important point of contention is how overseas development assistance not directly related to climate change mitigation is affected by funds provided to climate change mitigation.Brown J., Bird, N. and Schalatek, L., 2010
'Climate Finance Additionality: Emerging Definitions and their Implications'
Climate Finance Policy Brief No.2, ODI and Heinrich Boll Foundation
One of the outcomes of the UNFCC
Copenhagen Climate Conference The 2009 United Nations Climate Change Conference, commonly known as the Copenhagen Summit, was held at the Bella Center in Copenhagen, Denmark, between 7 and 18 December. The conference included the 15th session of the Conference of the Parti ...
was the
Copenhagen Accord The Copenhagen Accord is a document which delegates at the 15th session of the Conference of Parties (COP 15) to the United Nations Framework Convention on Climate Change agreed to "take note of" at the final plenary on 18 December 2009. The Accor ...
, in which developed countries promised to provide US$30 million between 2010 and 2012 of new and additional resources. Yet it remains unclear what exactly the definition of "additional" is.


Carbon pricing

Additional costs on greenhouse gas emissions can lower competitiveness of fossil fuels and accelerate investments into low-carbon sources of energy. A growing number of countries raise a fixed
carbon tax A carbon tax is a tax levied on the carbon emissions required to produce goods and services. Carbon taxes are intended to make visible the "hidden" social costs of carbon emissions, which are otherwise felt only in indirect ways like more sev ...
or participate in dynamic
carbon emission trading Emission trading (ETS) for carbon dioxide (CO2) and other greenhouse gases (GHG) is a form of carbon pricing; also known as cap and trade (CAT) or carbon pricing. It is an approach to limit climate change by creating a market with limited ...
(ETS) systems. In 2021, more than 21% of global greenhouse gas emissions were covered by a carbon price, a major increase due to the introduction of the
Chinese national carbon trading scheme The Chinese national carbon trading scheme is an intensity-based trading system for carbon dioxide emissions by China, which started operating in 2021. This emission trading scheme (ETS) creates a carbon market where emitters can buy and sell emi ...
. Trading schemes offer the possibility to limit emission allowances to certain reduction targets. However, an oversupply of allowances keeps most ETS at low price levels around $10 with a low impact. This includes the Chinese ETS which started with $7/t in 2021. One exception is the
European Union Emission Trading Scheme The European Union Emissions Trading System (EU ETS) is a "cap and trade" scheme where a limit is placed on the right to emit specified pollutants over an area and companies can trade emission rights within that area. It covers around 45% of th ...
where prices began to rise in 2018, reaching about €80/t in 2022. This results in additional costs of about €0.04/KWh for coal and €0.02/KWh for gas combustion for electricity, depending on the
emission intensity An emission intensity (also carbon intensity or C.I.) is the emission rate of a given pollutant relative to the intensity of a specific activity, or an industrial production process; for example grams of carbon dioxide released per megajoule o ...
. 2021 models of the
social cost of carbon The social cost of carbon (SCC) is the marginal cost of the impacts caused by emitting one extra tonne of greenhouse gas (carbon dioxide equivalent) at any point in time, inclusive of 'non-market' impacts on the environment and human health. Th ...
calculated a damage of more than $3000 per ton as a result of economy feedbacks and falling global
GDP Gross domestic product (GDP) is a monetary measure of the market value of all the final goods and services produced and sold (not resold) in a specific time period by countries. Due to its complex and subjective nature this measure is ofte ...
growth rates, while policy recommendations for a carbon price ranged from about $50 to $200. Industries which have high energy requirements and high emissions often pay only very low
energy tax An energy tax is a tax that increases the price of energy (Fisher ''et al''., 1996, p. 416). Arguments in favour of energy taxes have included the pursuit of macroeconomic objectives, e.g., fiscal deficit reduction in the 1990s, as well as env ...
es, or even none at all.IPCC (2022
Chapter 11: Industry
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Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
Methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...
from fossil fuel extraction are occasionally taxed, but methane and nitrous oxide from agriculture are typically left untaxed.


Cost estimates

Mitigation cost estimates depend on the baseline (in this case, a reference scenario that the alternative scenario is compared with), the way costs are modelled, and assumptions about future government policy. Cost estimates for mitigation for specific regions are dependent on the quantity of emissions "allowed" for that region in future, as well as the timing of interventions. Mitigation costs will vary according to how and when emissions are cut: early, well-planned action will minimise the costs. Globally, the benefits of keeping warming under 2 °C exceed the costs. Many economists estimate the cost of climate change mitigation at between 1% and 2% of
GDP Gross domestic product (GDP) is a monetary measure of the market value of all the final goods and services produced and sold (not resold) in a specific time period by countries. Due to its complex and subjective nature this measure is ofte ...
. One estimate stated that temperature increase can be limited to 1.5 °C for 1.7 trillion dollars a year. According to this study, a global investment of approximately $1.7 trillion per year would be needed to keep global warming below 1.5°C. Whereas this is a large sum, it is still far less than the
subsidies A subsidy or government incentive is a form of financial aid or support extended to an economic sector (business, or individual) generally with the aim of promoting economic and social policy. Although commonly extended from the government, the ter ...
governments currently provided to the ailing fossil fuel industry, estimated at more than $5 trillion per year by the International Monetary Fund. The economic repercussions of mitigation vary widely across regions and households, depending on policy design and level of international cooperation. Delayed global cooperation increases policy costs across regions, especially in those that are relatively carbon intensive at present. Pathways with uniform carbon values show higher mitigation costs in more carbon-intensive regions, in fossil-fuels exporting regions and in poorer regions. Aggregate quantifications expressed in GDP or monetary terms undervalue the economic effects on households in poorer countries; the actual effects on welfare and well-being are comparatively larger.IPCC (2022
Chapter 3: Mitigation pathways compatible with long-term goals
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Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
Cost–benefit analysis Cost–benefit analysis (CBA), sometimes also called benefit–cost analysis, is a systematic approach to estimating the strengths and weaknesses of alternatives. It is used to determine options which provide the best approach to achieving benefits ...
may be unsuitable for analysing climate change mitigation as a whole but still useful for analysing the difference between a 1.5 °C target and 2 °C. One way of estimating the cost of reducing emissions is by considering the likely costs of potential technological and output changes. Policy makers can compare the marginal abatement costs of different methods to assess the cost and amount of possible abatement over time. The marginal abatement costs of the various measures will differ by country, by sector, and over time.


Distributing emissions abatement costs

Mitigation at the speed and scale required to likely limit warming to 2 °C or below implies deep economic and structural changes, thereby raising multiple types of distributional concerns across regions, income classes and sectors. There have been different proposals on how to allocate responsibility for cutting emissions: PDF version: IPCC website.
Egalitarianism Egalitarianism (), or equalitarianism, is a school of thought within political philosophy that builds from the concept of social equality, prioritizing it for all people. Egalitarian doctrines are generally characterized by the idea that all hu ...
,
basic needs The basic needs approach is one of the major approaches to the measurement of absolute poverty in developing countries globally. It works to define the absolute minimum resources necessary for long-term physical well-being, usually in terms of ...
(as defined according to a minimum level of consumption), proportionality and polluter-pays principle. A specific proposal is the "equal per capita entitlements". This approach can be divided into two categories. In the first category, emissions are allocated according to national population. In the second category, emissions are allocated in a way that attempts to account for historical (cumulative) emissions.


Avoided costs of climate change effects

By limiting climate change, some of the costs of the
effects of climate change The effects of climate change impact the physical environment, ecosystems and human societies. The environmental effects of climate change are broad and far-reaching. They affect the water cycle, oceans, sea and land ice ( glaciers), sea le ...
can be avoided. According to the
Stern Review The Stern Review on the Economics of Climate Change is a 700-page report released for the Government of the United Kingdom on 30 October 2006 by economist Nicholas Stern, chair of the Grantham Research Institute on Climate Change and the Environm ...
, inaction can be as high as the equivalent of losing at least 5% of global gross domestic product (GDP) each year, now and forever (up to 20% of the GDP or more when including a wider range of risks and impacts), whereas mitigating climate change will only cost about 2% of the GDP. Also, delaying to take significant reductions in greenhouse gas emissions may not be a good idea, when seen from a financial perspective. Mitigation solutions are often evaluated in terms of costs and greenhouse gas reduction potentials, missing out on the consideration of direct effects on human well-being.


Policies and actors


Municipal policies and urban planning

Cities A city is a human settlement of notable size.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The Social Science Encyclopedia''. 2nd edition. London: Routledge. It can be def ...
have big potential for reducing greenhouse gas emissions. They emitted 28 GtCO2-eq in 2020 of combined CO2 and CH4 emissions. This was "through the production and consumption of goods and services". Climate-smart
urban planning Urban planning, also known as town planning, city planning, regional planning, or rural planning, is a technical and political process that is focused on the development and design of land use and the built environment, including air, water, ...
aims to reduce sprawl to reduce the distance travelled, thus lowering emissions from transportation. It supports mixed use of space, transit, walking, cycling, sharing vehicles can reduce urban emissions.
Urban forestry Urban forestry is the care and management of single trees and tree populations in urban settings for the purpose of improving the urban environment. Urban forestry involves both planning and management, including the programming of care and ...
, lakes and other blue and green infrastructure can reduce emissions directly and indirectly by reduced energy demand for cooling. Personal cars are extremely inefficient at moving passengers, while
public transport Public transport (also known as public transportation, public transit, mass transit, or simply transit) is a system of transport for passengers by group travel systems available for use by the general public unlike private transport, typi ...
and bicycles are many times more efficient in an urban context. Switching from cars by improving
walkability Walkability is a term for planning concepts best understood by the mixed-use of amenities in high-density neighborhoods where people can access said amenities by foot. It is based on the idea that urban spaces should be more than just transport ...
and cycling infrastructure is either free or beneficial to a country's economy as a whole.


National policies

Climate change mitigation policies can have a large and complex impact, both positive and negative, on the socio-economic status of individuals and countries. Without "well-designed and inclusive policies, climate change mitigation measures can place a higher financial burden on poor households." The most effective and economically efficient approach of achieving lower emissions in the energy sector is to apply a combination of market-based instruments (taxes, permits), standards, and information policies. Many countries are aiming for net zero emissions, and many have either
carbon tax A carbon tax is a tax levied on the carbon emissions required to produce goods and services. Carbon taxes are intended to make visible the "hidden" social costs of carbon emissions, which are otherwise felt only in indirect ways like more sev ...
es or
carbon emission trading Emission trading (ETS) for carbon dioxide (CO2) and other greenhouse gases (GHG) is a form of carbon pricing; also known as cap and trade (CAT) or carbon pricing. It is an approach to limit climate change by creating a market with limited ...
. As of 2021, three countries are carbon negative, meaning they remove from the atmosphere more
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and ...
then they emit. These countries;
Bhutan Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountainou ...
, Suriname and
Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...
; formed a small coalition at the 2021 United Nations Climate Change Conference and asked for help so that other countries will join it. Types of national policies that would support climate change mitigation include: * Regulatory standards: These set technology or performance standards, and can be effective in addressing the
market failure In neoclassical economics, market failure is a situation in which the allocation of goods and services by a free market is not Pareto efficient, often leading to a net loss of economic value. Market failures can be viewed as scenarios where indi ...
of informational barriers. If the costs of
regulation Regulation is the management of complex systems according to a set of rules and trends. In systems theory, these types of rules exist in various fields of biology and society, but the term has slightly different meanings according to context. Fo ...
are less than the benefits of addressing the market failure, standards can result in net benefits. One example are fuel-efficiency standards for cars. * Market-based instruments such as emission taxes and charges: an emissions tax requires domestic emitters to pay a fixed fee or tax for every tonne of CO2-eq GHG emissions released into the atmosphere. If every emitter were to face the same level of tax, the lowest cost way of achieving emission reductions in the economy would be undertaken first. In the real world, however, markets are not perfect, meaning that an emissions tax may deviate from this ideal. Distributional and equity considerations usually result in differential tax rates for different sources. * Tradable permits: Emissions can be limited with a permit system. A number of permits are distributed equal to the emission limit, with each liable entity required to hold the number of permits equal to its actual emissions. A tradable permit system can be cost-effective so long as transaction costs are not excessive, and there are no significant imperfections in the permit market and markets relating to emitting activities. * Voluntary agreements: These are agreements between government (public agencies) and industry. Agreements may relate to general issues, such as research and development, but in other cases, quantitative targets may be agreed upon. There is, however, the risk that participants in the agreement will free ride, either by not complying with the agreement or by benefitting from the agreement while bearing no cost. * Informational instruments: Poor information is recognized as a barrier to improved energy efficiency or reduced emissions. Examples of policies in this area include increasing public awareness of energy saving with home heating and insulation or emissions from meat and dairy products. However some say that for a politician asking people to eat less meat is "politically toxic". * Research and development policies: Some areas, such as soil, may differ by country and so need national research. Technologies may need financial support to reach commercial scale, for example floating wind power. * Low carbon power: Governments may relax planning regulations on solar power and onshore wind, and may partly finance technologies considered risky by the private sector, such as nuclear. * Demand-side management: This aims to reduce energy demand, e.g., through energy audits, labelling, and regulation. * Adding or removing subsidies: ** A subsidy for greenhouse gas emissions reductions pays entities a specific amount per tonne of CO2-eq for every tonne of greenhouse gas reduced or sequestered. Although subsidies are generally less efficient than taxes, distributional and
competitiveness In economics, competition is a scenario where different economic firmsThis article follows the general economic convention of referring to all actors as firms; examples in include individuals and brands or divisions within the same (legal) firm ...
issues sometimes result in energy/emission taxes being coupled with subsidies or tax exceptions. ** Creating subsidies and financial incentives: for example
energy subsidies Energy subsidies are measures that keep prices for customers below market levels, or for suppliers above market levels, or reduce costs for customers and suppliers. Energy subsidies may be direct cash transfers to suppliers, customers, or rel ...
to support clean generation which is not yet commercially viable such as tidal power. ** Phasing-out of unhelpful subsidies: Many countries provide
subsidies A subsidy or government incentive is a form of financial aid or support extended to an economic sector (business, or individual) generally with the aim of promoting economic and social policy. Although commonly extended from the government, the ter ...
for activities that impact emissions, e.g., subsidies in the agriculture and
energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of hea ...
sectors, and indirect subsidies for transport. Specific example
agricultural subsidies An agricultural subsidy (also called an agricultural incentive) is a government incentive paid to agribusinesses, agricultural organizations and farms to supplement their income, manage the supply of agricultural commodities, and influence the ...
for cattle or
fossil fuel subsidies Fossil fuel subsidies are energy subsidies on fossil fuels. They may be tax breaks on consumption, such as a lower sales tax on natural gas for residential heating; or subsidies on production, such as tax breaks on exploration for oil. Or ...
* A Green Marshall Plan, which calls for global central bank money creation to fund
green infrastructure Green infrastructure or blue-green infrastructure refers to a network that provides the “ingredients” for solving urban and climatic challenges by building with nature.Hiltrud Pötz & Pierre Bleuze (2011). Urban green-blue grids for sustainab ...
, * Market liberalization: Restructuring of
energy market Energy markets are national and international regulated markets that deal specifically with the trade and supply of energy. Energy market may refer to an electricity market, but can also refer to other sources of energy. Typically energy developme ...
s has occurred in several countries and regions. These policies have mainly been designed to increase competition in the market, but they can have a significant impact on emissions.


Phasing out fossil fuel subsidies


International agreements

Almost all countries are parties to the
United Nations Framework Convention on Climate Change The United Nations Framework Convention on Climate Change (UNFCCC) established an international environmental treaty to combat "dangerous human interference with the climate system", in part by stabilizing greenhouse gas concentrations in ...
(UNFCCC). The ultimate objective of the UNFCCC is to stabilize atmospheric concentrations of greenhouse gases at a level that would prevent dangerous human interference with the climate system.


Paris Agreement

The Paris Agreement has become the main current international agreement on combating climate change. Each country must determine, plan, and regularly report on the contribution that it undertakes to mitigate global warming. Climate change mitigation measures can be written down in national environmental policy documents like the nationally determined contributions (NDC). The Paris agreement succeeds the 1997 Kyoto Protocol which expired in 2020. Countries that ratified the Kyoto protocol committed to reduce their emissions of
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
and five other greenhouse gases, or engage in
emissions trading Emissions trading is a market-based approach to controlling pollution by providing economic incentives for reducing the emissions of pollutants. The concept is also known as cap and trade (CAT) or emissions trading scheme (ETS). Carbon emission ...
if they maintain or increase emissions of these gases. In 2015, two official UNFCCC scientific expert bodies came to the conclusion that, "in some regions and vulnerable ecosystems, high risks are projected even for warming above 1.5 °C". This expert position was, together with the strong diplomatic voice of the poorest countries and the island nations in the Pacific, the driving force leading to the decision of the Paris Conference 2015, to lay down this 1.5 °C long-term target on top of the existing 2 °C goal.


Additional commitments

In addition to the main agreements, there are many additional pledges made by international coalitions, countries, cities, regions and businesses. According to a report published in September 2019 before the 2019 UN Climate Action Summit, full implementation of all pledges, including those in the Paris Agreement, will be sufficient to limit temperature rise to 2 degrees but not to 1.5 degrees. After the report was published, additional pledges were made in the September climate summit and in December of that year. In December 2020 another climate action summit was held and important commitments were made. The organizers stated that, including the commitments expected in the beginning of the following year, countries representing 70% of the global economy will be committed to reach zero emissions by 2050. In September 2021 the US and EU launched the Global Methane Pledge to cut methane emissions by 30% by 2030. UK, Argentina, Indonesia, Italy and Mexico joined the initiative, "while Ghana and Iraq signaled interest in joining, according to a White House summary of the meeting, which noted those countries represent six of the top 15 methane emitters globally". Israel also joined the initiative Although not designed for this purpose, the
Montreal Protocol The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 September 1987, and entered into force o ...
has benefited climate change mitigation efforts. The Montreal Protocol is an international
treaty A treaty is a formal, legally binding written agreement between actors in international law. It is usually made by and between sovereign states, but can include international organizations, individuals, business entities, and other legal pe ...
that has successfully reduced emissions of ozone-depleting substances (for example, CFCs), which are also greenhouse gases.


Monitoring

Satellites are increasingly being used for locating and measuring greenhouse gas emissions and deforestation. Earlier, scientists largely relied on or calculated estimates of greenhouse gas emissions and governments' self-reported data. They can also evaluate the environmental impact of policies and events such as the impact of the COVID-19 pandemic on the environment. Various other technologies are also being used for
environmental monitoring Environmental monitoring describes the processes and activities that need to take place to characterize and monitor the quality of the environment. Environmental monitoring is used in the preparation of environmental impact assessments, as well a ...
.
Climate Action Tracker Climate Action Tracker (abbreviated CAT) is a research group with the aim of monitoring government action to achieve their reduction of greenhouse gas emissions with regard to international agreements. It is tracking climate action in 32 countries ...
described the situation on 9 November 2021 as follows: the global temperature will rise by 2.7 °C by the end of the century with current policies and by 2.9 °C with nationally adopted policies. The temperature will rise by 2.4 °C if only the pledges for 2030 are implemented, by 2.1 °C if the long-term targets are also achieved. If all the announced targets are fully achieved the rise in global temperature will peak at 1.9 °C and go down to 1.8 °C by the year 2100. All the information about all climate pledges is sent to the Global Climate Action Portal - Nazca. The scientific community is checking their fulfillment. While the status of most goals set for 2020 have not been evaluated in a definitive and detailed way or reported on by the media, the world failed to meet most or all international goals set for that year. As the 2021 United Nations Climate Change Conference occurred in Glasgow, the group of researchers running the
Climate Action Tracker Climate Action Tracker (abbreviated CAT) is a research group with the aim of monitoring government action to achieve their reduction of greenhouse gas emissions with regard to international agreements. It is tracking climate action in 32 countries ...
reported that of countries responsible for 85% of greenhouse gas emissions, only four polities (responsible for 6% of global greenhouse gas emissions) – EU, UK, Chile and Costa Rica – have published a detailed official policy
plan A plan is typically any diagram or list of steps with details of timing and resources, used to achieve an objective to do something. It is commonly understood as a temporal set of intended actions through which one expects to achieve a goal. ...
that describes the steps and ways by which 2030 mitigation targets could be realized. There are organizations that aim to transparently, neutrally and credibly monitor progress of climate change mitigation such as of pledges, goals, initiatives and other developments. How well each individual country is on track to achieving its Paris agreement commitments can be followed on-line. The negative impact of COVID-19 pandemic has placed a challenge to achieve the Paris Agreement, with less significant support from the respondents from less developed countries.


History

Historically climate change has been approached at a multinational level where a consensus decision is reached at the
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoniz ...
(UN), under the
United Nations Framework Convention on Climate Change The United Nations Framework Convention on Climate Change (UNFCCC) established an international environmental treaty to combat "dangerous human interference with the climate system", in part by stabilizing greenhouse gas concentrations in ...
(UNFCCC). This represents the dominant approach historically of engaging as many international governments as possible in taking action in on a worldwide public issue. There is a precedent that this model can work, as seen in the
Montreal Protocol The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 September 1987, and entered into force o ...
in 1987. The top-down framework of only utilizing the UNFCCC consensus approach has been proposed to be ineffective, with counter proposals of bottom up governance and decreasing the emphasis of the UNFCCC. The Kyoto Protocol to the
UNFCCC The United Nations Framework Convention on Climate Change (UNFCCC) established an international environmental treaty to combat "dangerous human interference with the climate system", in part by stabilizing greenhouse gas concentrations in th ...
(adopted in 1997) set out legally binding emission reduction commitments for the "Annex B" countries. The Protocol defined three international policy instruments (" Flexibility Mechanisms") which could be used by the Annex B countries to meet their emission reduction commitments. According to Bashmakov, use of these instruments could significantly reduce the costs for Annex B countries in meeting their emission reduction commitments. The European Union's mitigation target for 2020 was: Reduce greenhouse gas emissions by 20% from the level in 1990, produce 20% of energy from renewable sources, increase Energy Efficiency by 20%. The European Union claims that they have already achieved the 2020 target for emission reduction and have the legislation needed to achieve the 2030 targets. Already in 2018, its greenhouse gas emissions were 23% lower than those in 1990.


Society and culture


Barriers

Barriers to achieving climate change mitigation can be grouped into individual, institutional and market barriers. They differ for all the different mitigation options, regions and societies. Complicated issues around accounting of carbon dioxide removal can act as economic barriers, for example with regards to BECCS (
Bioenergy with carbon capture and storage Bioenergy with carbon capture and storage (BECCS) is the process of extracting bioenergy from biomass and capturing and storing the carbon, thereby removing it from the atmosphere. The carbon in the biomass comes from the greenhouse gas carbo ...
). The strategies that companies follow can act as a barrier but also as an "accelerator of
decarbonisation Climate change mitigation is action to limit climate change by reducing emissions of greenhouse gases or removing those gases from the atmosphere. The recent rise in global average temperature is mostly caused by emissions from fossil fuels bur ...
". In order to "decarbonise societies" the state (government) needs to play a predominant role because this requires a massive coordination effort. This strong government role, however, can only work well if there is
social cohesion Group cohesiveness (also called group cohesion and social cohesion) arises when bonds link members of a social group to one another and to the group as a whole. Although cohesion is a multi-faceted process, it can be broken down into four main co ...
,
political stability Political decay is a political theory, originally described by Samuel P. Huntington, which describes how chaos and disorder can arise from social modernization increasing more rapidly than political and institutional modernization. Huntington provi ...
and
trust Trust often refers to: * Trust (social science), confidence in or dependence on a person or quality It may also refer to: Business and law * Trust law, a body of law under which one person holds property for the benefit of another * Trust (bus ...
. For land-based mitigation options, finance is a major barrier, followed by "cultural values,
governance Governance is the process of interactions through the laws, norms, power or language of an organized society over a social system ( family, tribe, formal or informal organization, a territory or across territories). It is done by the gove ...
, accountability and institutional capacity" as other barriers. For
developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
, additional barriers to mitigation include: * The cost of capital increased in the early 2020s. A lack of available capital and finance is common in developing countries. Together with the absence of regulatory standards, this barrier supports the proliferation of inefficient equipment. * There are also financial and capacity barrier in many of these countries.


Impacts of the COVID-19 pandemic

The
COVID-19 pandemic The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identi ...
led some governments to shift their focus away from climate action, at least temporarily. Decreased human activity during the pandemic diverted attention from ongoing activities such as accelerated
deforestation of the Amazon rainforest The Amazon rainforest is the largest rainforest in the world, covering an area of 3,000,000 km2 (2,316,612.95 square miles). It represents over half of the planet's rainforests and comprises the largest and most biodiverse tract of tropi ...
. The hindrance of environmental policy efforts, combined with economic slowdown may have contributed to slowed investment in
green energy Energy is sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs". Most definitions of sustainable energy include considerations of environmental aspects such as greenh ...
technologies. In 2020,
carbon dioxide emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and la ...
fell by 6.4% or 2.3 billion tonnes globally. Greenhouse gas emissions rebounded later in the pandemic as many countries began lifting restrictions, with the direct impact of pandemic policies having a negligible long-term impact on climate change.


Examples by country


United States


China

In 2020, China committed to peak emissions by 2030 and reach
net zero Carbon neutrality is a state of net-zero carbon dioxide emissions. This can be achieved by balancing emissions of carbon dioxide with its removal (often through carbon offsetting) or by eliminating emissions from society (the transition to the " ...
by 2060; following the 2021 blackouts, officials indicated the 2030 target was something "to strive to" and not necessarily to be met. In order to limit warming to 1.5 °C coal plants in China without carbon capture must be phased out by 2045. The
Chinese national carbon trading scheme The Chinese national carbon trading scheme is an intensity-based trading system for carbon dioxide emissions by China, which started operating in 2021. This emission trading scheme (ETS) creates a carbon market where emitters can buy and sell emi ...
started in 2021.


European Union

The climate commitments of the
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
were divided into three main categories: targets for the year 2020 (now obsolete), for 2030 and for 2050. The European Union state that their policies are in line with the goal of the Paris Agreement. * Targets for 2030: Reduce greenhouse gas emission by 40% from the level of 1990. In 2019 The European Parliament adopted a resolution upgrading the target to 55%, produce 32% of energy from renewables, increase energy efficiency by 32.5%. * Target for 2050: become climate neutral.


See also

*
Attribution of recent climate change Efforts to scientifically ascertain and attribute mechanisms responsible for recent global warming and related climate changes on Earth have found that the main driver is elevated levels of greenhouse gases produced by human activities, with ...
*
Carbon budget A carbon budget is "the maximum amount of cumulative net global anthropogenic carbon dioxide () emissions that would result in limiting global warming to a given level with a given probability, taking into account the effect of other anthropogen ...
*
Climate movement The climate movement is a global social movement focused on pressuring governments and industry to take action (also called "climate action") addressing the causes and impacts of climate change. Environmental non-profit organizations have enga ...
* Climate change denial *
Nature-based solutions The term Nature-based solutions (NBS) refers to the sustainable management and use of natural features and processes to tackle socio-environmental challenges. These challenges include issues such as climate change ( mitigation and adaptation), ...
*
Tipping points in the climate system In climate science, a tipping point is a critical threshold that, when crossed, leads to large and often irreversible changes in the climate system. If tipping points are crossed, they are likely to have severe impacts on human society. Tippin ...


References

{{Authority control Biogeochemical cycle Biogeography Cycle Chemical oceanography Climate change policy Geochemistry Numerical climate and weather models Soil