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Climate change mitigation consists of actions to limit
global warming Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been , but the current changes are more rapid than any known events in Earth's history. The main cau ...

global warming
and its related effects. This involves reductions in human emissions of
greenhouse gas A greenhouse gas (GHG or GhG) is a gas Gas is one of the four fundamental states of matter (the others being solid, liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformat ...
es (GHGs) as well as activities that reduce their concentration in the atmosphere. It is one of the ways to respond to climate change, along with
adaptation In , adaptation has three related meanings. Firstly, it is the dynamic evolutionary process that fits s to their environment, enhancing their . Secondly, it is a state reached by the population during that process. Thirdly, it is a or adapti ...
.
Fossil fuel A fossil fuel is a -containing material formed underground from the remains of dead plants and animals that humans extract and to release for use. The main fossil s are , and , which humans extract through and . Fossil fuels may be burnt ...
combustion accounts for 89% of all
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is ...

carbon dioxide
() emissions and 68% of all
GHG emissions Greenhouse gas emissions are emissions of greenhouse gases created from a range of human activities that cause climate change Climate change includes both global warming driven by human emissions of greenhouse gases and the resulting ...
. The most important challenge is to stop burning
coal Coal is a combustible black or brownish-black sedimentary rock, formed as stratum, rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen ...

coal
,
oil An oil is any nonpolar chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can b ...

oil
, and
gas Gas is one of the four fundamental states of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space ...

gas
and use only
clean energy Energy system, Energy is sustainability, 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 environ ...
. Due to massive price drops,
wind power Wind power or wind energy is the use of s to . Wind power is a popular, , source that has a much smaller than burning s. s consist of many individual wind turbines, which are connected to the . In 2020, wind supplied almost 1600 of elec ...

wind power
and 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 u ...
(PV) are increasingly out-competing oil, gas and coal though these require
energy storage Energy storage is the capture of energy In physics, energy is the physical quantity, quantitative physical property, property that must be #Energy transfer, transferred to a physical body, body or physical system to perform Work (thermody ...

energy storage
and improved
electrical grid An electrical grid is an interconnected network for from producers to consumers. Electrical grids vary in size and can cover whole countries or continents. It consists of:Kaplan, S. M. (2009). Smart Grid. Electrical Power Transmission: Backgr ...
s. As low-emission energy is deployed at large scale, transport and heating can shift to these mostly electric sources. Mitigation of climate change may also be achieved by changes in
agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases in sedentary behaviors su ...

agriculture
, transport, forest-management (
reforestation Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forest A forest is an area of land dominated by tree In botany, a tree is a perennial plant with an elongated Plant stem, ste ...
and
preservation Preservation may refer to: Heritage and conservation * Preservation (library and archival science), activities aimed at prolonging the life of a record while making as few changes as possible * Preservation (magazine), ''Preservation'' (magazine ...

preservation
),
waste management Waste management (or waste disposal) includes the processes and actions required to manage from its inception to its final disposal. This includes the , transport, treatment and disposal of waste, together with monitoring and regulati ...

waste management
, buildings, and industrial systems.
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 Earth ...
emissions, which have a high short-term impact, can be targeted by reductions in
cattle Cattle, taurine cattle, Eurasian cattle, or European cattle (''Bos taurus'' or ''Bos primigenius taurus'') are large s. They are a prominent modern member of the subfamily and the most widespread species of the genus '. In , adult females a ...

cattle
and
meat consumption Meat is animal Animals (also called Metazoa) are organisms that form the Animalia. With few exceptions, animals , , are , can , and grow from a hollow sphere of , the , during . Over 1.5 million animal have been —of which ar ...
. Political and economical responses to date include forms of
carbon pricing A carbon price — the method widely agreed to be the most efficient way for nations to reduce global warming Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns ...
by
carbon tax A carbon tax is a tax levied on the carbon Carbon (from la, carbo "coal") is a chemical element with the Symbol (chemistry), symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—making four electrons available ...

carbon tax
es and
carbon emission trading Carbon emissions trading is a form of emissions trading Emissions trading (also known as cap and trade, emissions trading scheme or ETS) is a market-based approach to controlling pollution by providing economic incentives for reducing the e ...
, reductions of
fossil fuel 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 relat ...
, making national promises and laws, subsidies, simplified regulations for the integration of low-carbon energy and divestment from fossil fuel finance. 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 International is an adjective (also used as a noun) meaning "between nations". International may also refer to: Music Albums * ''International'' ...
(UNFCCC). The ultimate objective of the UNFCCC is to stabilize atmospheric concentrations of GHGs at a level that would prevent dangerous human interference with the climate system. In 2010, Parties to the UNFCCC agreed that future global warming should be limited to below relative to the pre-
industrial Industrial may also refer to: Industry * Industrial archaeology, the study of the history of the industry * Industrial engineering, engineering dealing with the optimization of complex industrial processes or systems * Industrial loan company, a f ...
level. With the
Paris Agreement The Paris Agreement (french: l'accord de Paris) is an agreement within the United Nations Framework Convention on Climate Change (UNFCCC), on climate change mitigation, Climate change adaptation, adaptation, and Climate finance, finance, signed i ...
of 2015, this was confirmed. The current trajectory of global greenhouse gas emissions does not appear to be consistent with limiting global warming to below 1.5 or 2 °C despite the limit being economically beneficial globally and to many top GHG emitters such as China and India.


Goals of stabilizing greenhouse gas concentrations

The UNFCCC aims to stabilize greenhouse gas (GHG) concentrations in the atmosphere at a level where
ecosystems 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 ...
can adapt naturally to climate change,
food production The food industry is a complex, global network of diverse business Business is the activity of making one's living or making money by producing or buying and selling Product (business), products (such as goods and services). Simply put, it ...
is not threatened, and
economic development In the economic An economy (; ) is an area of the production Production may be: Economics and business * Production (economics) * Production, the act of manufacturing goods * Production, in the outline of industrial organization, the act o ...
can proceed in a sustainable fashion. Currently human activities are adding CO2 to the atmosphere faster than natural processes can remove it. In 2018, human activities were estimated to have caused approximately 1.0 °C of global warming above pre-industrial levels, with a likely range of 0.8 °C to 1.2 °C.


Needed emissions cuts

According to the emissions gap report of the
United Nations Environment Programme 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 Maurice Frederick Strong, (April 29, 1929 – November 27, 20 ...
for limiting warming to 1.5 °C GHG emissions should be cut from the level of 2020 by 76% by the year 2030. A small group of scientists leaked some information on the results of Working Group III (Mitigation of Climate Change) from 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 Wo ...
. As governments can change the summaries for policymakers (SPM) for IPCC reports, the scientists were afraid that politicians might dilute this information in the summary. According to the leaked information, humanity should cut GHG emissions by 50% by 2030 and completely by 2050 with a peak by 2025 in order to limit warming to 1.5 °C. According to the Special Report on Global Warming of 1.5 °C limiting warming below or close to would require to decrease net CO2 emissions by around 45% by 2030 from the level of 2010 and reach ''net zero'' by 2050. For limiting global warming to below , CO2 emissions should decline by 25% by 2030 and by 100% by 2075. Non-CO2 emissions need to be strongly reduced at similar levels in both scenarios.


Calculations

The IPCC works with the concept of a fixed carbon
emissions budget Emission may refer to: Chemical products * Emission of air pollutants, notably: ** Flue gas, gas exiting to the atmosphere via a flue ** Exhaust gas, flue gas generated by fuel combustion ** Emission of greenhouse gases, which absorb and emit ra ...
. If emissions remain on the current level of 42 Gt, the carbon budget for 1.5 °C could be exhausted in 2028. The rise in temperature to that level would occur with some delay between 2030 and 2052. Even if it was possible to achieve negative emissions in the future, 1.5 °C must not be exceeded at any time to avoid the loss of ecosystems. In the Special Report on Global Warming of 1.5 °C, the IPCC emphasized the benefits of keeping global warming below this level. Emissions pathways with no or limited overshoot would require rapid and far-reaching transitions in energy, land, urban and infrastructure including transport and buildings, and industrial systems. Pathways that aim for limiting warming to 1.5 °C by 2100 after a temporary temperature overshoot rely on large-scale deployment of carbon dioxide removal (CDR) measures, which are uncertain and entail clear risks. A 2011 study suggested that, after leaving room for emissions for food production for 9 billion people, to keep the global temperature rise below 2 °C, emissions will have to peak almost immediately in the developed world (or non-Annex 1 nations), peaking around 2020 and decline at about 10% each year until zero emissions are reached around 2030 with non-Annex 1 nations' emissions peaking in 2030 (due to "social and economic development and poverty eradication" being "the first and overriding priorities").


Effects

If emissions will be reduced to zero, the warming might stop in 10 to 20 years. Potential feedback effects lead to a high degree of uncertainty in any projection.
Climate change mitigation scenarios Climate change mitigation scenarios are possible futures in which global warming is reduced by deliberate actions, such as a comprehensive switch to alternative energy, energy sources other than fossil fuels. These are actions that minimize emissi ...
from the
IPCC Fifth Assessment Report The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations responsible for advancing knowledge on Attribution of recent climate change, human-induced climate change. It was established in 1988 by the ...
cover a range from of warming by the end of the 21st century if emissions immediately decline and go to net zero by 2050, or if emissions continue upwards until they are triple current levels.


Drivers of global warming


By sectors and countries

Climate change is driven by: * greenhouse gas emissions * loss of carbon sinks such as of tropical forests * various smaller factors such (Earth's
albedo Albedo (prounounced ; la, albedo, meaning 'whiteness') is the measure of the diffuse reflection Diffuse reflection is the reflectionReflection or reflexion may refer to: Philosophy * Self-reflection Science * Reflection (physics), a comm ...

albedo
and the
Solar cycle The solar cycle or solar magnetic activity cycle is a nearly periodic 11-year change in the Sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its ...

Solar cycle
can also have an effect on the climate but are not responsible for current climate change) * feedback effects in the Earth system that alter any of the above.


By greenhouse gas

Carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

Carbon dioxide
() is the dominant emitted greenhouse gas, while
methane Methane (, ) is a chemical compound with the chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes a ...
() emissions almost have the same short-term impact.
Nitrous oxide Nitrous oxide, commonly known as laughing gas, nitrous, or nos, is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is an ...
(N2O) and
fluorinated gasesFluorinated gases (F-gases) are man-made gases that can stay in the atmosphere for centuries and contribute to a global greenhouse effect The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's sur ...
(F-Gases) play a minor role. With the
Kyoto Protocol The Kyoto Protocol was an international treaty A treaty is a formal, legally binding written agreement between actors in international law International law, also known as public international law and law of nations, is the set of ru ...

Kyoto Protocol
, the reduction of almost all anthropogenic greenhouse gases has been addressed. GHG emissions are measured in equivalents determined by their
global warming potential Global warming potential (GWP) is the heat In thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, entropy, and the physical properties of ...

global warming potential
(GWP), which depends on their lifetime in the atmosphere. 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 A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes a ...
, hydrofluorocarbons (HFCs),
tropospheric ozone Ground level ozone (O3) also tropospheric ozone, is a trace gas#REDIRECT Trace gas Trace gases are those gases in the atmosphere other than nitrogen Nitrogen is the chemical element with the Symbol (chemistry), symbol N and atomic number 7. ...
and
black carbon Chemically, black carbon (BC) is a component of fine Particulates, 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 o ...
persist in the atmosphere for a period ranging from days to 15 years as compared to carbon dioxide which can remain in the atmosphere for millennia. Reducing SLCP emissions can cut the ongoing rate of global warming by almost half and reduce the projected Arctic warming by two-thirds. GHG emissions in 2019 were estimated at 57.4 Gte, while emissions alone made up 42.5 Gt including land-use change (LUC).using 100 year
global warming potential Global warming potential (GWP) is the heat In thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, entropy, and the physical properties of ...

global warming potential
from IPCC-AR4


Carbon dioxide ()

* Fossil fuel:
oil An oil is any nonpolar chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can b ...

oil
,
gas Gas is one of the four fundamental states of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space ...

gas
and
coal Coal is a combustible black or brownish-black sedimentary rock, formed as stratum, rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen ...

coal
(89%) are the major driver of anthropogenic global warming with annual emissions of 35.6 Gt in 2019. *
Cement A cement is a binder (material), binder, a substance used for construction that solidification, sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (constru ...
production (4%) is estimated at 1.42 Gt * Land-use change (LUC) is the imbalance of
deforestation deforestation in 1750-2004 (net loss) showing anthropogenic modification of remaining forest. File:MODIS (2020-08-01).jpg, 300px, Dry seasons, exacerbated by climate change, and the use of slash-and-burn methods for clearing tropical forest ...

deforestation
and
reforestation Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forest A forest is an area of land dominated by tree In botany, a tree is a perennial plant with an elongated Plant stem, ste ...
. Estimations are very uncertain at 4.5 Gt.
Wildfire A wildfire, bushfire, wildland fire or rural fire is an unplanned, unwanted, uncontrolled fire BBQ. Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction ...

Wildfire
s alone cause annual emissions of about 7 Gt * Non-energy use of fuels, carbon losses in coke ovens, and flaring in crude oil production.


Methane (CH4)

Methane has a high immediate impact with a 5-year
global warming potential Global warming potential (GWP) is the heat In thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, entropy, and the physical properties of ...

global warming potential
of up to 100. Given this, the current 389 Mt of methane emissions has about the same short-term global warming effect as emissions, with a risk to trigger irreversible changes in climate and ecosystems. For methane, a reduction of about 30% below current emission levels would lead to a stabilization in its atmospheric concentration. * Fossil fuels (32%), again, account for most of the methane emissions including coal mining (12% of methane total), gas distribution and leakages (11%) as well as
gas venting Gas venting, more specifically known as natural-gas venting or methane venting, is the intentional and controlled release of gases containing alkane hydrocarbons - predominately methane - into earth's atmosphere. It is a widely used method for ...
in oil production (9%). * Livestock (28%) with cattle (21%) as the dominant source, followed by buffalo (3%), sheep (2%), and goats (1.5%). * Human waste and wastewater (21%): When biomass waste in landfills and organic substances in domestic and industrial wastewater is decomposed by bacteria in anaerobic conditions, substantial amounts of methane are generated. * Rice cultivation (10%) on flooded rice fields is another agricultural source, where anaerobic decomposition of organic material produces methane.


Nitrous oxide ()

N2O has a high GWP and significant Ozone Depleting Potential (ODP). It is estimated that the global warming potential of N2O over 100 years is 265 times greater than CO2. For N2O, a reduction of more than 50% would be required for a stabilization. * Most emissions (56%) by agriculture, especially meat production: cattle (droppings on pasture), fertilizers, animal manure. * Combustion of fossil fuels (18%) and . *Industrial production of
adipic acid Adipic acid or hexanedioic acid is the organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's abili ...

adipic acid
and
nitric acid Nitric acid (), also known as ''aqua fortis'' (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid. The pure compound is colorless, but older samples tend to acquire a yellow cast due to decomposition into nitroge ...

nitric acid
.


F-Gases

Fluorinated gases include
hydrofluorocarbons Hydrofluorocarbons (HFCs) are man-made organic compounds that contain fluorine and hydrogen atoms, and are the most common type of organofluorine compounds. Most are gases at room temperature and pressure. They are frequently used in air condition ...
(HFC), perfluorocarbons (PFC),
sulfur hexafluoride Sulfur hexafluoride (SF6) or sulphur hexafluoride (British spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in Engli ...
(SF6), and
nitrogen trifluoride Nitrogen trifluoride () is an inorganic, colorless, non-flammable , Germany Image:Tu braunschweig 750 grad ofen.jpg, 250px, Germany, German test apparatus for determining combustibility at Technische Universität Braunschweig A combustible ...

nitrogen trifluoride
(NF3). They are used by switchgear in the power sector, semiconductor manufacture, aluminium production and a large unknown source of SF6. Continued phase down of manufacture and use of HFCs under the Kigali Amendment to the
Montreal Protocol The largest Antarctic ozone hole recorded as of September 2006 The Montreal Protocol is an international treaty A treaty is a formal, legally binding written agreement between actors in international law International law, also known ...
will help reduce HFC emissions and concurrently improve the energy efficiency of appliances that use HFCs like air conditioners, freezers and other refrigeration devices.


Black carbon

Black carbon Chemically, black carbon (BC) is a component of fine Particulates, 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 o ...
is formed through the incomplete combustion of fossil fuels,
biofuel Biofuel is fuel that is produced through contemporary processes from biomass, rather than by the very slow geological processes involved in the formation of fossil fuels, such as oil. Since biomass technically can be used as a fuel directly (e. ...

biofuel
, and
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...

biomass
. It is not a greenhouse gas but a
climate forcing Earth's climate Climate is the long-term average of weather, typically averaged over a period of 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some o ...
agent. Black carbon can absorb sunlight and reduce
albedo Albedo (prounounced ; la, albedo, meaning 'whiteness') is the measure of the diffuse reflection Diffuse reflection is the reflectionReflection or reflexion may refer to: Philosophy * Self-reflection Science * Reflection (physics), a comm ...

albedo
when deposited on snow and ice. Indirect heating can be caused by the interaction with clouds. Black carbon stays in the atmosphere for only several days to weeks. Emissions may be mitigated by upgrading coke ovens, installing particulate filters on diesel-based engines, reducing
routine flaring Routine flaring, also known as production flaring, is a method and current practice of disposing of large unwanted amounts of associated petroleum gas (APG) during crude oil extraction. The gas is first separated from the liquids and solids d ...
, and minimizing open burning of biomass.


Fossil fuel substitution

As most greenhouse gas emissions are due to fossil fuels, rapidly phasing out oil, gas and coal is critical. In a system based on fossil fuels, demand is expected to double until 2050. Switching to renewable energy combined with the electrification of transport and heating can lower the primary energy demand significantly. Currently, less than 20% of energy is used as electricity. A global transition to
100% renewable energy Comparing trends in worldwide energy use, the growth of renewable energy to 2015 is the green line 100% renewable energy is where all energy use is sourced from renewable energy sources. The endeavor to use 100% renewable energy for electr ...
across all sectors is feasible well before 2050. With dropping prices for wind and solar energy as well as storage, the transition no longer depends on economic viability but is considered as a question of political will. For allowing for a 50% probability of limiting global warming by 2050 to 1.5 °C large amounts, as preliminary estimated globally and per region, of fossil fuels would need to be secured from extraction. The
sustainable energy Energy In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, t ...
system is more efficient and cost effective than the existing system. Operators investing into fossil fuels face a growing risk of stranded assets.


Low-carbon energy sources

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 Renewable energy is energy that is collected from renewable resource File:Global Vegetation.jpg, Global vegetation A renewable resource, ...
fluctuates a lot. This can be tackled by extending grids over large areas with a sufficient capacity or by using
energy storage Energy storage is the capture of energy In physics, energy is the physical quantity, quantitative physical property, property that must be #Energy transfer, transferred to a physical body, body or physical system to perform Work (thermody ...

energy storage
.
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 achi ...
of industrial energy consumption can help to balance the production of renewable energy production and its demand. Electricity production by
biogas Biogas is the mixture of gas Gas is one of the four fundamental states of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and ...

biogas
and
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 water's kinetic energy In physics, the kineti ...
can follow the energy demand. Both can be driven by variable energy prices. The deployment of
renewable energy Renewable energy is energy that is collected from renewable resource File:Global Vegetation.jpg, Global vegetation A renewable resource, also known as a flow resource, is a natural resource which will replenish to replace the portion resou ...
would have to be accelerated six-fold though to stay under the 2 °C target. The global
primary energy Primary energy (PE) is an energy In , energy is the that must be to a or to perform on the body, or to it. Energy is a ; the law of states that energy can be in form, but not created or destroyed. The unit of measurement in the ...
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. 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 A carbon price — the method widely agreed to be the most efficient way for nations to reduce global warming Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. ...
can increase the competitiveness of renewable energy. * = 2018. All other values for 2019.


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 u ...
(PV) has become the cheapest way to produce electric energy in many regions of the world, with production costs down to 0.015 US$/KWh in desert regions. 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 electricity ...
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 Concentrated solar power (CSP, also known as concentrating solar power, concentrated solar thermal) systems generate solar power by using mirrors or lenses to concentrate a large area of sunlight onto a receiver. Electricity is generated whe ...
(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 Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth Earth is the third planet from ...

Solar water heating
has doubled between 2010 and 2019. Total installed solar water heating systems provide a capacity of 501 GWth, with 67% of the global share in
China China (), officially the People's Republic of China (PRC; ), is a country in East Asia East Asia is the eastern region of Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern Hemisphere ...

China
. Photovoltaic thermal hybrid solar collectors combine PV and solar heating.


Wind power

Regions in the higher northern and southern latitudes have the highest potential for wind power. Installed capacity has reached 650 GW in 2019.
Offshore wind power Offshore wind power or offshore wind energy is the use of wind farms constructed in bodies of water, usually in the ocean, to harvest wind energy to generate electricity. Higher wind speeds are available offshore compared to on land, so offshore w ...
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.


Hydro power

Hydroelectricity Hydroelectricity, or hydroelectric power, is electricity produced from hydropower Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water Water (chemical formula H2O) is ...
plays a leading role in countries like Brazil, Norway and China. but there are geographical limits and environmental issues.
Tidal power#REDIRECT Tidal power Tidal power or tidal energy is harnessed by converting energy from tide (U.S.), low tide occurs roughly at moonrise and high tide with a high Moon, corresponding to the simple gravity model of two tidal bulges; at most ...
can be used in coastal regions.


Bioenergy

Biogas Biogas is the mixture of gas Gas is one of the four fundamental states of matter In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and ...

Biogas
plants 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 Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...

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. Transporting fuels over long distances and excessive use of nitrogen fertilisers can reduce the emissions savings made by the same fuel compared to natural gas by between 15 and 50 per cent. Renewable
biofuel Biofuel is fuel that is produced through contemporary processes from biomass, rather than by the very slow geological processes involved in the formation of fossil fuels, such as oil. Since biomass technically can be used as a fuel directly (e. ...

biofuel
s are starting to be used in aviation.


Nuclear power

In most 1.5 °C pathways of the
Intergovernmental Panel on Climate Change The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations responsible for advancing knowledge on Attribution of recent climate change, human-induced climate change. It was established in 1988 by the ...
's Special Report on Global Warming of 1.5 °C the share of nuclear power is increased. The main advantage of nuclear energy is the ability to deliver large amounts of
base load The baseload (also base load) on a grid 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 in ...
when renewable energy is not available. On the other hand, environmental and security risks could outweigh the benefits. As of 2019, no country has found a final solution to nuclear waste which can cause future damage and costs over more than one million years. Separated plutonium and enriched uranium could be used for nuclear weapons, which is considered to be a strategical motivation for countries to promote nuclear power. The according risks are comparable to climate change. The Fukushima Daiichi nuclear disaster, Fukushima disaster is estimated to cost taxpayers ~$187 billion and radioactive waste management is estimated to cost the EU ~$250 billion by 2050. 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 is often considered to be the large construction and operating costs when compared to alternatives of sustainable energy sources whose costs are decreasing and which are the fastest-growing source of electricity generation. Nuclear power avoided 2–3% of total global GHG emissions in 2021. Limited Uranium mining, uranium-235 supply inhibits substantial expansion scenarios with novel nuclear technologies Nevertheless, Nuclear energy in China, China is building a significant number of new power plants, albeit significantly fewer reactors than originally planned. the cost of extending nuclear power 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.


= Nuclear fusion

= Nuclear fusion research, in the form of the International Thermonuclear Experimental Reactor, ITER and other experimental projects, is underway but fusion energy is not likely to be commercially widespread before 2050. – Projected fusion power timeline


Carbon neutral and negative fuels

Fossil fuel may be phased-out with carbon-neutral fuel, carbon-neutral and carbon-negative pipeline and transportation fuels created with power-to-gas and gas to liquids technologies.


Natural gas

Natural gas, which is mostly
methane Methane (, ) is a chemical compound with the chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes a ...
, is viewed as a bridge fuel since it produces about half as much as burning coal.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> Gas-fired power plants can provide the required flexibility in electricity production in combination wind and solar energy. But methane is itself a potent greenhouse gas, and it currently leaks from production wells, storage tanks, pipelines, and urban distribution pipes for natural gas. In a low-carbon scenario, gas-fueled power plants could still continue operation if methane was produced using power-to-gas technology with renewable energy sources. Another possibility is to convert the natural gas to hydrogen and Fossil fuel power station#Running the power station on hydrogen converted from natural gas, use the latter instead to run the thermal power stations.


Energy storage

Wind energy and photovoltaics can deliver large amounts of electric energy but not at any time and place. One approach is the conversation into storable forms of energy. This generally leads to losses in efficiency. A study by Imperial College London calculated the lowest levelised cost of different systems for mid-term and seasonal storage. In 2020, Pumped-storage hydroelectricity, pumped hydro (PHES), Compressed-air energy storage, compressed air (CAES) and Lithium-ion battery, Li-on batteries are most cost effective depending on charging rhythm. For 2040, a more significant role for Li-on and hydrogen is projected. *Lithium-ion battery, Li-on batteries are widely used in battery storage power stations and, , are starting to be used in vehicle-to-grid storage. They provide a sufficient round-trip efficiency of 75-90 %. However their production can cause environmental problems. Levelized costs for battery storage have drastically fallen to 0.15 US$/KWh * Hydrogen may be useful for seasonal energy storage. The low efficiency of 30% of the reconversion to electricity must improve dramatically before hydrogen storage can offer the same overall energy efficiency as batteries. Thermal energy in the conversion process can be used for district heating. For the electricity grid a German study estimated high costs of 0.176 €/KWh for reconversion concluding that substituting the electricity grid expansion entirely with hydrogen reconversion systems does not make sense from an economic standpoint. The concept of solar hydrogen is discussed for remote desert projects where grid connections to demand centers are not available. Because it has more energy per unit volume sometimes it may be better to use hydrogen in ammonia.


Super grids

Long-distance power lines help to minimize storage requirements. A continental transmission network can smoothen local variations of wind energy. With a global grid, even photovoltaics could be available all day and night. The strongest high-voltage direct current (HVDC) connections are quoted with losses of only 1.6% per 1000 km with a clear advantage compared to AC. HVDC is currently only used for point-to-point connections. Meshed HVDC grids are reported to be ready-to-use in Europe and to be in operation in China by 2022. China has built many HVDC connections within the country and supports the idea of a global, intercontinental grid as a backbone system for the existing national alternating current, AC grids. A super grid in the US in combination with renewable energy could reduce GHG emissions by 80%.


Smart grid and load management

Instead of expanding grids and storage for more power, electricity demand can be adjusted on the consumer side. This can flatten demand peaks. Traditionally, the energy system has treated consumer demand as fixed. Instead, data systems can combine with advanced software to pro-actively manage demand and respond to energy market prices. Net energy metering#Time of use metering, Time of use tariffs are a common way to motivate electricity users to reduce their peak load consumption. On a household level, charging electric vehicles or running heat pumps combined with hot water storage when wind or sun energy are available reduces electricity costs. Dynamic demand plans have devices passively shut off when stress is sensed on the electrical grid. This method may work very well with thermostats, when power on the grid sags a small amount, a low power temperature setting is automatically selected reducing the load on the grid. Refrigerators or heat pumps can reduce their consumption when clouds pass over solar installations. Consumers need to have a smart meter in order for the utility to calculate credits. Smart Scheduling of activities and processes can adjust demand to fluctuating supply. Demand response devices can receive all sorts of messages from the grid. The message could be a request to use a low power mode similar to dynamic demand, to shut off entirely during a sudden failure on the grid, or notifications about the current and expected prices for power. This allows electric cars to recharge at the least expensive rates independent of the time of day. Vehicle-to-grid uses a car's battery to supply the grid temporarily. Smart grids could also monitor/control residential devices that are noncritical during periods of peak power consumption, and return their function during nonpeak hours. Further flexibility techniques by which smart grids can help manage the variable renewable energy, variability of renewable energy (VRE) and increase efficiency include VRE forecasting methodologies.


Energy conservation and efficiency

Improved energy efficiency in energy-efficient buildings, buildings, industrial processes and sustainable transportation, transportation could reduce the world's energy needs in 2050 by one third, and help control global emissions of greenhouse gases. Service labels like Energy Star provide information on the energy consumption of products. A procurement toolkit to assist individuals and businesses buy energy efficient products that use low Global Warming Potential, GWP refrigerants was developed by the Sustainable Purchasing Leadership Council. The cogeneration of electric energy and district heat also improves efficiency.


Research and development

Scientific research and development can improve available technological options such as of smart grids, green hydrogen, energy efficiency, emerging energy sources like floating solar and of energy storage, as well as assisting in the design and practical implementation of efficient, timely and – e.g. socially – viable global and regional fossil fuel substitution strategies. Key components of such work may include peer review criticism, replication, scientific review, review, standardization, production of (often initially conflicting) conclusions, implementation and analysis of trials, and the development of alternatives.


Carbon sinks and removal

Carbon sequestration is the storing of carbon in to a reservoir called a carbon sink such as growing a forest or through artificial carbon dioxide removal such as carbon capture and storage, direct air capture. Carbon dioxide removal is vital in climate change mitigation even with the best case scenarios of reducing carbon dioxide emissions as levels of in the atmosphere are already at damaging levels. Conservation biology, Conserving areas by Protected area, protecting areas can boost the carbon sequestration capacity. The European Union, through the EU Biodiversity Strategy for 2030 targets to protect 30% of the sea territory and 30% of the land territory by 2030. In 2021, seven countries (the G7) pledged to protect or preserve at least 30% of the world's land and 30% of the world's oceans to halt biodiversity loss. A survey by the United Nations Development Programme of public opinion on climate change found that forests and land conservation policies were the most popular solutions of climate change mitigation.


Carbon storage in land ecosystems

Forests can be considered as a permanent storage for . Trees capture while growing. This is released immediately when wood is burned. If dead wood remains untouched, only some of the carbon returns to the atmosphere as decomposition proceeds. Existing forests still capture more carbon than they release. Protecting healthy soils and recovering damaged soils could remove 5.5 billion tons of carbon dioxide from the atmosphere annually, which is approximately equal to the annual emissions of the US.


Afforestation

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 of more than 900 GtC (2300 Gt) until 2100. Generally, it takes more than 20 years to compensate for carbon emissions related to the establishment of the plantations. According to the Trillion Tree Campaign, planting additional 1.2 trillion trees would cancel out the last 10 years of CO2 emissions. However, this is not considered a viable alternative to aggressive emissions reduction. Such plantations would need to be so large, they would eliminate most natural ecosystems or reduce food production.


Preventing deforestation and desertification

Avoided
deforestation deforestation in 1750-2004 (net loss) showing anthropogenic modification of remaining forest. File:MODIS (2020-08-01).jpg, 300px, Dry seasons, exacerbated by climate change, and the use of slash-and-burn methods for clearing tropical forest ...

deforestation
reduces CO2 emissions at a rate of 1tonne of CO2 per $1–5 in opportunity costs from lost agriculture. Cutting trees for woodfuel, the main source of energy for the poor, and clearing forests for agriculture are major drivers of desertification and deforestation. Transferring rights over land from public domain to its indigenous inhabitants, who have had a stake for millennia in preserving the forests that they depend on, is argued to be a cost-effective strategy to conserve forests. This includes the protection of such rights entitled in existing laws, such as the The Scheduled Tribes and Other Traditional Forest Dwellers (Recognition of Forest Rights) Act, 2006, Forest Rights Act in India, where concessions to land continue to go mostly to powerful companies. The transferring of such rights in China, perhaps the largest land reform in modern times, has been argued to have increased forest cover. Granting title of the land has shown to have two or three times less clearing than even state run parks, notably in the Brazilian Amazon. Even while the largest cause of deforestation in the world's second largest rainforest in the Congolian rainforests, Congo is smallholder agriculture and charcoal production, areas with community concessions have significantly less deforestation as communities are incentivized to manage the land sustainably, even reducing poverty. Conservation methods that exclude humans, called "fortress conservation", and even evict inhabitants from protected areas often lead to more exploitation of the land as the native inhabitants then turn to work for extractive companies to survive. As enforcement of forest protection may not sufficiently address the drivers behind deforestation – the largest of which being the production of beef in Deforestation of the Amazon rainforest, the case of the Amazon rainforest – it may also need policies. These could effectively ban or progressively eco-tariff, discourage deforestation-associated trade via e.g. product information requirements, Global Forest Watch, satellite monitoring and product certifications.


Preventing permafrost leaks

The global warming induced thawing of the permafrost#Climate change effects, permafrost, which stores about two times the amount of the carbon currently released in the atmosphere, releases the potent greenhouse gas, Atmospheric methane, methane, in a positive feedback, positive feedback cycle that is feared to lead to a tipping point (climatology), tipping point called runaway climate change. While the permafrost is about 14 degrees Fahrenheit, a blanket of snow insulates it from the colder air above which could be 40 degrees below zero Fahrenheit. A method proposed to prevent such a scenario is to bring back large herbivores such as seen in Pleistocene Park, where they keep the ground cooler by reducing snow cover height by about half and eliminating shrubs and thus keeping the ground more exposed to the cold air.


Reforestation

Reforestation 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 With increased intensive agriculture and urbanization, 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. Russia, the United States and Canada have the most land suitable for reforestation. Planting new trees can be expensive, especially for the poor who often live in areas of
deforestation deforestation in 1750-2004 (net loss) showing anthropogenic modification of remaining forest. File:MODIS (2020-08-01).jpg, 300px, Dry seasons, exacerbated by climate change, and the use of slash-and-burn methods for clearing tropical forest ...

deforestation
, and can be a risky investment as, for example, studies in the Sahel have found that 80 percent of planted trees die within two years. Instead, helping native species sprout naturally is much cheaper and more likely to survive, with even long deforested areas still containing an "underground forest" of living roots and tree stumps that are still able to regenerate. This could include pruning and coppicing the tree to accelerate its growth and that also provides woodfuel, a major source of deforestation. Such practices are centuries old but the biggest obstacle towards natural regrowth of trees are legal ownership of the trees by the state, often as a way of selling such timber rights to business people, leading to seedlings being uprooted by locals who saw them as a liability. Changes in the law in Mali and Niger allowing ownership of trees to residents has led to what has been called the largest positive environmental transformation in Africa, with it being possible to discern from space the border between Niger and the more barren land in Nigeria, where the law has not changed.


Proforestation

Proforestation is promoting forests to capture their full ecological potential. Forest restoration, Restoring all degraded forests all over the world could capture about 205 GtC (750 Gt). 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. Allowing proforestation in some secondary forests will increase their accumulated carbon and biodiversity over time. Strategies for proforestation include Rewilding (conservation biology), rewilding, such as reintroducing apex predators and keystone species as, for example, predators keep the population of herbivores in check (which reduce the Biosequestration, biomass of vegetation). Another strategy is establishing wildlife corridors connecting isolated protected areas.


Carbon storage in water ecosystems

The Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC) estimated in 2013 that one-third of humankind's annual emissions of are absorbed by the oceans. Absorption by phytoplankton is very uncertain but may be 40% of all CO2 emissions. However, dissolved in water leads to ocean acidification, which harms marine life as acidification lowers the level of carbonate ions available for calcifying organisms to form their shells. These organisms include plankton species that contribute to the foundation of the ocean food webs. Acidification also impacts on a broad range of other physiological and ecological processes, such as Ocean deoxygenation, fish respiration, larval development and changes in the solubility of both nutrients and toxins. Blue carbon refers to carbon dioxide removed from the atmosphere by the world's ocean ecosystems through plant and macroalgae growth and the accumulation and burial of organic matter in the soil.


Wetlands

Wet areas have lower oxygen levels dissolved than in the air and so oxygen reliant decomposition of organic matter by microbes into is decreased. Peatland 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. Restoration of degraded peatlands can be done by blocking drainage channels in the peatland, and Protected area, allowing natural vegetation to recover.


Coastal waters

Mangroves, salt marshes and seagrasses 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, dredging for coastal development and fertilizer runoff have damaged coastal habitats.


Synthetic carbon dioxide removal


Direct air capture

Direct air capture is a process of capturing directly from the ambient air (as opposed to capturing from Point source pollution, point sources and generating a concentrated stream of for Carbon sequestration, sequestration or Carbon capture and utilization, utilization or production of carbon-neutral fuel 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.
It is notable that the availability of cheap energy and appropriate sites for carbon capture and storage, geological storage of carbon may make carbon dioxide air capture viable commercially.


Carbon capture and storage

Carbon capture and storage (CCS) is a method to mitigate climate change by capturing
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is ...

carbon dioxide
(CO2) from large Point source pollution, point sources, such as cement factories or Bioenergy with carbon capture and storage, 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, 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.


Enhanced weathering


Solar geoengineering

Solar geoengineering, Solar Radiation Modification (SRM) methods involve reducing the amount of incoming solar radiation reaching the surface and reducing optical thickness and cloud lifetime. The variability of the climate system would make it difficult to detect the efficacy or side-effects of SRM intervention. Uncertainties including technological maturity, physical understanding and potential impacts constrain the ability to implement SRM in the near future.


Decarbonization by sector


Transport

Transportation emissions account for 15% of emissions worldwide. Increasing the use of public transport, low-carbon freight transport and cycling are important components of transport decarbonization. Electric vehicles and environmental design in rail transportation, environmentally friendly rail help to reduce the consumption of fossil fuels. In most cases, electric trains are more efficient than environmental impact of aviation, air transport and road transport, truck transport. Other efficiency means include improved public transport, smart mobility, carsharing and hybrid vehicle, electric hybrids. Fossil-fuel powered passenger cars can Electric vehicle conversion, be converted to electric propulsion. The production of alternative fuel without GHG emissions is only possible with high conversion losses. Furthermore, moving away from a car-dominated transport system towards low-carbon advanced public transport system is important.


Electric vehicles

Between a quarter and three-quarters of cars on the road by 2050 are forecast to be electric vehicles. EVs use 38 megajoules per 100 km in comparison to 142 megajoules per 100 km for ICE cars. Hydrogen can be a solution for long-distance transport by trucks and hydrogen-powered ships where batteries alone are too heavy. GHG emissions depend on the amount of green energy being used for battery or fuel cell production and charging. In a system mainly based on electricity from fossil fuels, emissions of electric vehicles can even exceed those of diesel combustion.


Shipping

In the shipping industry, the use of liquefied natural gas (LNG) as a marine bunker fuel is driven by emissions regulations. Ship operators have to switch from heavy fuel oil to more expensive oil-based fuels, implement costly flue gas treatment technologies or switch to Marine LNG Engine, LNG engines. Methane slip, when gas leaks unburned through the engine, lowers the advantages of LNG. Maersk, the largest container shipping line and vessel operator in the world, warns of stranded assets when investing into transitional fuels like LNG. The company lists green ammonia 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. 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 a EU-backed project, is in operation in Denmark.


Air travel

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 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. In October 2016, the 191 nations of the ICAO established the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), requiring operators to purchase carbon offsets to cover their emissions above 2020 levels, starting from 2021. This is voluntary until 2027. The environmental impact of aviation increases at high altitudes. Contrail, Contrails, not only airplane greenhouse gas emissions, have a significant impact on climate change.


Heating and cooling

The buildings sector accounts for 23% of global energy-related emissions About half of the energy is used for space and water heating. A combination of electric heat pumps and Zero heating building, building insulation can reduce the primary energy demand significantly. Generally, electrification of heating and cooling would only reduce GHG emissions if the electric power comes from low-carbon sources. A fossil-fuel power station may only deliver 3 units of electrical energy for every 10 units of fuel energy released. Electrifying heating and cooling loads may also provide a flexible resource that can participate in demand response to integrate variable renewable resources into the grid.


Heat pumps

A modern heat pump typically produces around two to six times more thermal energy than electrical energy consumed, giving an effective efficiency of 200 to 600%, depending on the coefficient of performance and the outside temperature. It uses an electrically driven compressor to operate a heat pump and refrigeration cycle, refrigeration cycle that extracts heat energy from outdoor air and moves that heat to the space to be warmed. In the summer months, the cycle can be reversed for air conditioner, air conditioning. In areas with average winter temperatures well below freezing, ground source heat pumps are more efficient than air-source heat pumps. The high purchase price of a heat pump compared to resistance heaters may be offset when air conditioning is also needed. With a market share of 30% and clean electricity, heat pumps could reduce global emissions by 8% annually. Using ground source heat pumps could reduce around 60% of the
primary energy Primary energy (PE) is an energy In , energy is the that must be to a or to perform on the body, or to it. Energy is a ; the law of states that energy can be in form, but not created or destroyed. The unit of measurement in the ...
demand and 90% of emissions of natural gas boilers in Europe in 2050 and make handling high shares of renewable energy easier. Using surplus renewable energy in heat pumps is regarded as the most effective household means to reduce global warming and fossil fuel depletion.


Cooling

Refrigeration and air conditioning account for about 10% of global emissions caused by fossil fuel-based energy production and the use of fluorinated gases. Slashing HFC consumption by 80% by midcentury could avoid more than 0.4 °C of global warming by the end of the century. About 90% of the emissions occur at the end of the equipment's life. Solutions include investing in proper disposal and refrigerants that are less polluting. 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.


Electric resistant heating

radiant heating, Radiant heaters in households are cheap and widespread but less efficient than heat pumps. In areas like Norway, Brazil, and Quebec that have abundant hydroelectricity, electric heat and hot water are common. Large scale hot water tanks can be used for demand-side management and store variable renewable energy over hours or days.


Agriculture

As 25% of greenhouse gas emissions (GHGs) are coming from agriculture and land use, it is impossible to limit temperature rise to 1.5 degrees without addressing the emissions from this sector. During 2021 United Nations Climate Change Conference, 45 countries pledged to give more than 4 billion dollars for transition to sustainable agriculture. The organization "Slow Food" expressed concern about the effectivity of the spendings, as they concentrate on technological solutions and reforestation en place of "a holistic agroecology that transforms food from a mass-produced commodity into part of a sustainable system that works within natural boundaries." With 21% of the global methane emissions, cattle are a major driver on global warming. 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 for the production of 1 kg beef in Brazil when using a 30-year time horizon. Other livestock, manure management and rice cultivation also produce relevant GHG emissions, in addition to fossil fuel combustion in agriculture. Agricultural changes may require complementary laws and policies to drive and support dietary shifts, including changes in pet food, increases in organic food products, and substantial reductions of meat-intake (food miles usually do not play a large role). Regenerative agriculture includes conservation tillage, diversity, rotation and cover crops, minimizing physical disturbance, minimizing the usage of chemicals. It has other benefits like improving the state of the soil and consequently yields. Restoring grasslands stores CO2 with estimates that increasing the carbon content of the soils in the world's 3.5 billion hectares of agricultural grassland by 1% would offset nearly 12 years of CO2 emissions. Allan Savory, as part of holistic management, claims that while large herds are often blamed for desertification, prehistoric lands supported large or larger herds and areas where herds were removed in the United States are still desertifying. Grazers, such as livestock that are not left to wander, would eat the grass and would minimize any grass growth. However, carbon sequestration is maximized when only part of the leaf matter is consumed by a moving herd as a corresponding amount of root matter is sloughed off too sequestering part of its carbon into the soil. In the United States, soils account for about half of agricultural GHGs while agriculture, forestry and other land use emits 24%. The US EPA says soil management practices that can reduce the emissions of nitrous oxide () from soils include fertilizer usage, irrigation, and tillage. Important mitigation options for reducing the greenhouse gas emissions from livestock include genetic selection, introduction of Methanotroph, methanotrophic bacteria into the rumen, vaccines, feeds, toilet-training, diet modification and grazing management. Other options include just using ruminant-free alternatives instead, such as milk substitutes and meat analogues. Non-ruminant livestock (e.g. poultry) generates far fewer emissions. Methods that enhance carbon sequestration in soil include no-till farming, residue mulching and crop rotation, all of which are more widely used in organic farming 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. 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. Farming within forest growth is sometimes called agroforestry or farmer-managed natural regeneration. In Burkina Faso and Mali, local farmers such as Yacouba Sawadogo innovated with methods such as Zaï that have improved the quality of the soil and thus helping prevent carbon emitting desertification. 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.


Urban planning

Effective urban planning to reduce urban sprawl, sprawl aims to decrease the distance travelled by vehicles, lowering emissions from transportation. Personal cars are extremely inefficient at moving passengers, while public transport and bicycles are many times more efficient (as is the simplest form of human transportation, walking). All of these are encouraged by urban/community planning and are an effective way to reduce greenhouse gas emissions. Inefficient land use development practices have increased infrastructure costs as well as the amount of energy needed for transportation, community services, and buildings. Switching from cars by improving walkability and cycling infrastructure is either free or beneficial to a country's economy as a whole. At the same time, a growing number of citizens and government officials have begun advocating a smarter approach to land use planning. These smart growth practices include compact community development, multiple transportation choices, mixed land uses, and practices to conserve green space. These programs offer environmental, economic, and quality-of-life benefits; and they also serve to reduce energy usage and greenhouse gas emissions. Reducing the number of cars on the road, for example through proof-of-parking requirements, corporate car sharing, road reallocation (from only car use to cycling road, ...), circulation plans, Parallel parking#Legality, bans on on-street parking or by increasing the costs of car ownership can help in reducing traffic congestion in cities. Approaches such as New Urbanism and transit-oriented development seek to reduce distances travelled, especially by private vehicles, encourage public transit and make walking and cycling more attractive options. This is achieved through "medium-density", mixed-use development, mixed-use planning and the concentration of housing within walking distance of town centers and transport nodes. Smarter growth land use policies have both a direct and indirect effect on energy consuming behavior. For example, transportation energy usage, the number one user of petroleum fuels, could be significantly reduced through more compact and mixed use land development patterns (urban agriculture, urban trees), which in turn could be served by a greater variety of non-automotive based transportation choices.


Building design

Emissions from house, housing are substantial, and government-supported energy efficiency programmes can make a difference. New buildings can be constructed using passive solar building design, low-energy building, or zero-energy building techniques, using renewable heat sources. Existing buildings can be made more efficient through the use of insulation, high-efficiency appliances (particularly water heating, hot water heaters and Furnace (house heating), furnaces), insulated glazing, double- or triple-glazed gas-filled windows, external window shades, and building orientation and siting. Renewable heat sources such as Ground source heat pump, shallow geothermal and passive solar energy reduce the amount of greenhouse gasses emitted. In addition to designing buildings which are more energy-efficient to heat, 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 (e.g. by painting roofs white) and planting trees. This saves energy because it cools buildings and reduces the urban heat island effect thus reducing the use of air conditioning.


Governmental action

A study suggests that politics, political choices that effectively delay mitigation have the largest effect on the share of costs and risks of mitigation options, followed by geophysical uncertainties, social factors influencing future energy demand and technological uncertainties. Climate Action Tracker 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. Recent proposals suggest i.a. investments supporting a green recovery after the COVID-19 pandemic.


Paris agreement and Kyoto Protocol

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 2015 United Nations Climate Change Conference, Paris Conference 2015, to lay down this 1.5 °C long-term target on top of the existing 2 °C goal. The
Paris Agreement The Paris Agreement (french: l'accord de Paris) is an agreement within the United Nations Framework Convention on Climate Change (UNFCCC), on climate change mitigation, Climate change adaptation, adaptation, and Climate finance, finance, signed i ...
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 Intended nationally determined contributions, nationally determined contributions (NDC). The Paris agreement succeeds the 1997
Kyoto Protocol The Kyoto Protocol was an international treaty A treaty is a formal, legally binding written agreement between actors in international law International law, also known as public international law and law of nations, is the set of ru ...

Kyoto Protocol
which expired in 2020. List of Kyoto Protocol signatories, Countries that ratified the Kyoto protocol committed to reduce their emissions of
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is ...

carbon dioxide
and five other greenhouse gases, or engage in emissions trading if they maintain or increase emissions of these gases. How well each individual country is on track to achieving its Paris agreement commitments can be followed on-line.


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 the year 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 Some information about the pledges is collected and analyzed in the Global Climate Action (portal), Global Climate Action portal, which enables the scientific community to check their fulfilment.


Carbon pricing

Additional costs on GHG 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 Carbon (from la, carbo "coal") is a chemical element with the Symbol (chemistry), symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—making four electrons available ...

carbon tax
or participate in dynamic
carbon emission trading Carbon emissions trading is a form of emissions trading Emissions trading (also known as cap and trade, emissions trading scheme or ETS) is a market-based approach to controlling pollution by providing economic incentives for reducing the e ...
(ETS) systems. In 2021, more than 21% of global GHG emissions were covered by a carbon price, a major increase due to the introduction of the Chinese national carbon trading scheme. 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 where prices began to rise in 2018, exceeding €63/t ( $) in 2021. 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. Latest models of the social cost of carbon calculate a damage of more than $3000 per ton as a result of economy feedbacks and falling global GDP growth rates, while policy recommendations for a carbon price range from about $50 to $200. Most energy taxes are still levied on energy products and motor vehicles, rather than on emissions directly. Non-transport sectors as the agricultural sector, which produces large amounts of methane, are typically left untaxed by current policies. The revenue of carbon pricing can used to support policies that promote carbon neutrality. Another approach the concept of a carbon fee and dividend which includes the redistribution on a per-capita basis. As a result, households with a low consumption can even benefit from carbon pricing.


Montreal protocol

Although not designed for this purpose, the
Montreal Protocol The largest Antarctic ozone hole recorded as of September 2006 The Montreal Protocol is an international treaty A treaty is a formal, legally binding written agreement between actors in international law International law, also known ...
has benefited climate change mitigation efforts. The Montreal Protocol is an international treaty that has successfully reduced emissions of ozone-depleting substances (for example, Chlorofluorocarbon, CFCs), which are also greenhouse gases.


Enaction of a state of emergency

Enacting a state of emergency may be composed of two elements: declaring a state of emergency that has formulated real-world i.e. legal effects and the associated enabling or ensuring of rapid complementary large-scale changes in human activity for the articulated purposes. To date, many governments have acknowledged, sometimes in the form of tentative text-form "declarations", that humanity is essentially in a state of climate emergency. In November 2021, Greta Thunberg and other climate activists asked the United Nation to declare a level 3 systemwide climate emergency. It has been proposed that the national security sector could play a unqiue role in the development of a global climate-emergency mobilisation of labour and resources to build a zero-emission economy and enact decarbonization.


Costs and benefits

Globally, the benefits of keeping warming under 2 °C exceed the costs.. However, some consider cost–benefit analysis 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. The OECD has been applying economic models and qualitative assessments to inform on climate change benefits and tradeoffs.


Costs

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. Mitigation costs will vary according to how and when emissions are cut: early, well-planned action will minimise the costs. Many economists estimate the cost of climate change mitigation at between 1% and 2% of Gross domestic product, GDP. In 2019, scientists from Australia and Germany presented the "One Earth Climate Model" showing how 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 Paris Agreement, keep global warming below 1.5°C. The method used by the One Earth Climate Model does not resort to dangerous geo-engineering methods. Whereas this is a large sum, it is still far less than the Energy subsidies, subsidies governments currently provided to the ailing fossil fuel industry, estimated at more than $5 trillion per year by the International Monetary Fund. Abolishing fossil fuel subsidies is very important but must be done carefully to avoid making poor people poorer. Ian Parry, lead author of the 2021 IMF report "Still Not Getting Energy Prices Right: A Global and Country Update of Fossil Fuel Subsidies", said: “Some countries are reluctant to raise energy prices because they think it will harm the poor. But holding down fossil fuel prices is a highly inefficient way to help the poor, because most of the benefits accrue to wealthier households. It would be better to target resources towards helping poor and vulnerable people directly."


Benefits

By limiting climate change, some of the costs of the effects of climate change can be avoided. According to the Stern Review, 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 Stern Review#Stern's later comments, 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. 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. Climate change mitigation is also an issue of intergenerational justice with nonintervention thought by some to violate future people's freedom – conversely, mitigation may preserve societal freedoms and range of viable basic choices. The research organization Project Drawdown identified global climate solutions and ranked them according to their benefits. Early deaths due to fossil fuel air pollution with a temperature rise to 2 °C cost more globally than mitigation would: and in India cost 4 to 5 times more. Air pollution#Reduction and regulation, 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.


Sharing

One of the aspects of mitigation is how to share the costs and benefits of mitigation policies. Rich people tend to emit more GHG than poor people. PDF version: IPCC website. Activities of the poor that involve emissions of GHGs are often associated with basic needs, such as cooking. For richer people, emissions tend to be associated with things such as eating beef, cars, Frequent-flyer program, frequent flying, and Heating, ventilation, and air conditioning, home heating. The impacts of cutting emissions could therefore have different impacts on human welfare economics, welfare according to wealth.


Distributing emissions abatement costs

There have been different proposals on how to allocate responsibility for cutting emissions (Banuri et al., 1996, pp. 103–105): * Egalitarianism: this system interprets the problem as one where each person has equal rights to a global resource, i.e., polluting the atmosphere. * Basic needs: this system would have emissions allocated according to basic needs, as defined according to a minimum level of consumption (economics), consumption. Consumption above basic needs would require countries to buy more emission rights. From this viewpoint, developing countries would need to be at least as well off under an emissions control regime as they would be outside the regime. * Proportionality and polluter-pays principle: Proportionality reflects the ancient Aristotelianism, Aristotelian principle that people should receive in proportion to what they put in, and pay in proportion to the damages they cause. This has a potential relationship with the "polluter-pays principle", which can be interpreted in a number of ways: ** ''Historical responsibilities'': this asserts that allocation of emission rights should be based on patterns of past emissions. Two-thirds of the stock of GHGs in the atmosphere at present is due to the past actions of developed countries (Goldemberg et al., 1996, p. 29). Web version: IPCC website. ** ''Comparable burdens and ability to pay'': with this approach, countries would reduce emissions based on comparable burdens and their ability to take on the costs of reduction. Ways to assess burdens include monetary costs per head of population, as well as other, more complex measures, like the UNDP's Human Development Index. ** ''Willingness to pay'': with this approach, countries take on emission reductions based on their ability to pay along with how much they benefit from reducing their emissions.


Specific proposals

* Ad hoc: Lashof (1992) and Cline (1992) (referred to by Banuri et al., 1996, p. 106), for example, suggested that allocations based partly on GNP could be a way of sharing the burdens of emission reductions. This is because GNP and economic activity are partially tied to carbon emissions. * Equal per capita entitlements: this is the most widely cited method of distributing abatement costs, and is derived from egalitarianism (Banuri et al., 1996, pp. 106–107). 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. * Status quo: with this approach, historical emissions are ignored, and current emission levels are taken as a status quo right to emit (Banuri et al., 1996, p. 107). An analogy for this approach can be made with fishery, fisheries, which is a common, limited resource. The analogy would be with the atmosphere, which can be viewed as an exhaustible natural resource (Goldemberg et al., 1996, p. 27). In international law, one state recognized the long-established use of another state's use of the fisheries resource. It was also recognized by the state that part of the other state's economy was dependent on that resource.


Barriers to implementation

It has been suggested that the main barriers to implementation are uncertainty, institutional void, short time horizon of policies and politicians and missing motives and willingness to start adapting. When information on climate change is held between the large numbers of actors involved it can be highly dispersed, context specific or difficult to access causing fragmentation to be a barrier. The short time horizon of policies and politicians often means that climate change policies are not implemented in favour of socially favoured societal issues. Statements are often posed to keep the illusion of political action to prevent or postpone decisions being made.Biesbroek. G.R, Termeer. C.J.A.M, Kabat. P, Klostermann.J.E.M (unpublished) Institutional governance barriers for the development and implementation of climate adaptation strategies, Working paper for the International Human Dimensions Programme (IHDP) conference "Earth System Governance: People, Places, and the Planet", 2–4 December, Amsterdam, the Netherlands There may be cause for concern about metal requirement for relevant technologies such as
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 u ...
. Many developing nations have made national adaptation programs which are frameworks to prioritize adaption needs.


Carbon budgets by country

An international policy to allocate carbon budgets to individual countries has not been implemented. This question raises fairness issues. With a linear reduction starting from the status quo, industrial countries would have a greater share of the remaining global budget. Using an equal share per capita globally, emission cuts in industrial countries would have to be extremely sharp.


Geopoliticial impacts

In 2019, oil and gas companies were listed by Forbes with sales of US$4.8 trillion, about 5% of the global List of countries by GDP (nominal), GDP. Net importers such as China and the EU would gain advantages from a transition to low-carbon technologies driven by technological development, energy efficiency or climate change policy, while Russia, the USA or Canada could see their fossil fuel industries nearly shut down. On the other hand, countries with large areas such as Australia, Russia, China, the US, Canada and Brazil and also Africa and the Middle East have a potential for huge installations of renewable energy. The production of renewable energy technologies requires rare-earth elements with new supply chains.


Territorial policies

Many countries are aiming for Carbon neutrality, net zero emissions, and many have either
carbon tax A carbon tax is a tax levied on the carbon Carbon (from la, carbo "coal") is a chemical element with the Symbol (chemistry), symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—making four electrons available ...

carbon tax
es or
carbon emission trading Carbon emissions trading is a form of emissions trading Emissions trading (also known as cap and trade, emissions trading scheme or ETS) is a market-based approach to controlling pollution by providing economic incentives for reducing the e ...
.


United States

Efforts to reduce greenhouse gas emissions by the United States include energy policy of the United States, energy policies which encourage efficiency through programs like Energy Star, Commercial Building Integration, and the Industrial Technologies Program. In the absence of substantial federal action, state governments have adopted emissions-control laws such as the Regional Greenhouse Gas Initiative in the Northeast and the Global Warming Solutions Act of 2006 in California. In 2019 a new climate change bill was introduced in Minnesota. One of the targets, is making all the energy of the state carbon free, by 2030.


China

In 2020, China committed to peak emissions by 2030 and reach net zero 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 Electricity sector in China#Coal power, coal plants in China without carbon capture must be phased out by 2045. The Chinese national carbon trading scheme started in 2021. With more than 12 Gt, China is the largest GHG emitter worldwide, still investing into new coal plants. On the other hand, China is also installing the largest capacities of renewable energy worldwide. In recent years, Chinese companies have flooded the world market with high-performance photovoltaic modules, resulting in competitive prices. China is also building a HVDC grid. Chinas export-embodied emissions are estimated at a level of 1.7 Gt per year.


European Union

The climate commitments of the European Union are divided into three main categories: targets for the year 2020, 2030 and 2050. The European Union claim that their policies are in line with the goal of the #Paris_agreement_and_Kyoto_Protocol, Paris Agreement. * Targets for 2020: Reduce GHG emissions by 20% from the level in 1990, produce 20% of energy from renewable sources, increase Energy Efficiency by 20%. * Targets for 2030: Reduce GHG 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%. * Targets for 2050: become climate neutral. 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 GHG emissions were 23% lower that in 1990.


New Zealand

New Zealand made significant pledges on climate change mitigation in the year 2019: reduce emissions to zero by 2050, plant 1 billion trees by 2028, and encouraging farmers to reduce emissions by 2025 or face higher taxes Already in 2019 New Zealand banned new offshore oil and gas drilling and decided the climate change issues will be examined before every important decision. In early December 2020, Prime Minister of New Zealand, Prime Minister Jacinda Ardern declared a climate change emergency and pledged that the New Zealand Government would be carbon neutral by 2025. Key goals and initiatives include requiring the public sector to buy only electric or hybrid vehicles, government buildings will have to meet new "green" building standards, and all 200 coal-fired boilers in public service buildings will be phased out.


Nigeria

To mitigate the adverse effect of climate change, not only did Nigeria sign the Paris agreement to reduce emission, in its national climate pledge, the Nigerian government has promised to "work towards" ending gas flaring by 2030. In order to achieve this goal, the government established a Gas Flare Commercialisation Programme to encourage investment in practices that reduce gas flaring. Also, the federal government has approved a new National Forest Policy which is aimed at "protecting ecosystems" while enhancing social development. Effort is also been made to stimulate the adoption of climate-smart agriculture and the planting of trees.


Developing countries

In order to reconcile economic development with mitigating carbon emissions, developing countries need particular support, both financial and technical. One of the means of achieving this is the Kyoto Protocol's Clean Development Mechanism (CDM). The World Bank's Prototype Carbon Fund is a public private partnership that operates within the CDM. An important point of contention, however, is how overseas development assistance not directly related to climate change mitigation is affected by funds provided to climate change mitigation.Jessica Brown, Neil Bird and Liane Schalatek (2010
Climate finance additionality: emerging definitions and their implications
Overseas Development Institute
One of the outcomes of the UNFCC Copenhagen Climate Conference was the Copenhagen Accord, 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 and the European Commission has requested its member states to define what they understand to be additional, and researchers at the Overseas Development Institute have found four main understandings: # Climate finance classified as aid, but additional to (over and above) the Millennium Development Goals#Funding commitment, '0.7%' ODA target; # Increase on previous year's Official Development Assistance (ODA) spent on climate change mitigation; # Rising ODA levels that include climate change finance but where it is limited to a specified percentage; and # Increase in climate finance not connected to ODA. The main point being that there is a conflict between the OECD states budget deficit cuts, the need to help developing countries adapt to develop sustainably and the need to ensure that funding does not come from cutting aid to other important Millennium Development Goals. 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. In an attempt to provide more opportunities for developing countries to adapt clean technologies, UNEP and WTO urged the international community to reduce trade barriers and to conclude the Doha Development Round, Doha trade round "which includes opening trade in environmental goods and services". In 2019 week of climate action in Latin America and the Caribbean result in a declaration in which leaders says that they will act to reduce emissions in the sectors of transportation, energy, urbanism, industry, forest conservation and land use and "sent a message of solidarity with all the people of Brazil suffering the consequences of the Deforestation of the Amazon rainforest, rainforest fires in the Amazon region, underscoring that protecting the world's forests is a collective responsibility, that forests are vital for life and that they are a critical part of the solution to climate change".


Legal action

In some countries, those affected by climate change may be able to sue major greenhouse gas emitters. Climate change litigation, Litigation has been attempted by entire countries and peoples, such as Palau and the Inuit, as well as non-governmental organizations such as the Sierra Club. Investor-owned coal, oil, and gas corporations could be legally and morally liable for climate-related human rights violations. Litigations are often carried out via collective pooling of effort and resources such as via organizations like Greenpeace, which sued a Polish coal utility and a German car manufacturer.


Requirements

Proving that Extreme event attribution, some weather events are due specifically to global warming is now possible, and methodologies have been developed to show the increased risk of other events caused by global warming. For a legal action for negligence (or similar) to succeed, "Plaintiffs ... must show that, more probably than not, their individual injuries were caused by the risk factor in question, as opposed to any other cause. This has sometimes been translated to a requirement of a relative risk of at least two." Another route (though with little legal bite) is the World Heritage Convention, if it can be shown that climate change is affecting World Heritage Sites like Mount Everest.


Of countries

Besides countries suing one another, there are also cases where people in a country have taken legal steps against their own government. Legal action has been taken to try to force the United States Environmental Protection Agency, US Environmental Protection Agency to regulate greenhouse gas emissions under the Clean Air Act (United States), Clean Air Act. In the Netherlands and Belgium, organisations such as the foundation Urgenda and the Klimaatzaak in Belgium have also sued their governments as they believe their governments are not meeting the emission reductions they agreed to. Urgenda have already won their case against the Dutch government. In 2019, 22 states, six cities and Washington, DC, in United States, sued the Trump administration for repealing the Clean Power Plan. In 2020 a group of Swiss senior women sued their government for too weak action on stopping climate change. They claimed that the increase in heat waves caused by climate change, particularly impacts elderly people. In November 2020 the European Court of Human Rights ordered 33 countries to respond to the climate lawsuit from four children and two adults living in Portugal. The lawsuit will be treated as a priority by the court. In 2021, Germany's supreme constitutional court has ruled that the government's climate protection measures are insufficient to protect future generations and that the government had until the end of 2022 to improve its Climate Protection Act.


Of companies

According to a 2004 study commissioned by Friends of the Earth, ExxonMobil, and its predecessors caused 4.7 to 5.3 percent of the world's human-made carbon dioxide emissions between 1882 and 2002. The group suggested that such studies could form the basis for eventual legal action. In 2015, Exxon received a subpoena. According to the ''The Washington Post, Washington Post'' and confirmed by the company, the attorney general of New York, Eric Schneiderman, opened an investigation into the possibility that the company had misled the public and investors about the risks of climate change. In October 2019, the trial began. Massachusetts also sued Exxon, for hiding the impact of climate change. In May 2021, in ''Milieudefensie et al v Royal Dutch Shell'', the district court of The Hague ordered Royal Dutch Shell to cut its global carbon emissions by 45% by the end of 2030 compared to 2019 levels.


Societal responses


Investment

More than 1000 organizations with a worth of US$8 trillion have made commitments to fossil fuel divestment. Socially responsible investing funds allow investors to invest in funds that meet high environmental, social and corporate governance (ESG) standards. Proxy firms can be used to draft guidelines for investment managers that take these concerns into account. As well as a policy risk, Ernst & Young, Ernst and Young identify physical, secondary, liability, transitional and reputation-based risks. Therefore, it is increasingly seen to be in the interest of investors to accept climate change as a real threat which they must proactively and independently address.


Funding

Funding, such as the Green Climate Fund, is often provided by nations, groups of nations and increasingly NGO and private sources. These funds are often channelled through the Global Environment Facility, Global Environmental Facility (GEF). This is an environmental funding mechanism in the World Bank which is designed to deal with global environmental issues.Evans. J (forthcoming 2012) Environmental Governance, Routledge, Oxon The GEF was originally designed to tackle four main areas: biological diversity, climate change, international waters and ozone layer depletion, to which land degradation and persistent organic pollutant were added. The GEF funds projects that are agreed to achieve global environmental benefits that are endorsed by governments and screened by one of the GEF's implementing agencies.


Economics

There is a debate about a potentially critical need for new ways of economic accounting, including directly monitoring and value (economics), quantifying positive real-world environmental effects such as air quality improvements and related unprofitable Work (human activity), work like forest protection, alongside far-reaching structural changes of lifestyles as well as acknowledging and moving beyond the limits of current economics such as GDP. Some argue that for effective climate change mitigation degrowth has to occur, while some argue that eco-economic decoupling could limit climate change enough while continueing high rates of traditional GDP growth. There is also research and debate about requirements of how economic systems could be transformed for sustainability – such as how their jobs could transition harmonously into green jobs – a just transition – and how relevant sectors of the economy – like the renewable energy industry and the bioeconomy – could be adequately supported. While degrowth is often believed to be associated with decreased living standards and austerity measures, many of its proponents seek to expand universal public goods (such as public transport), increase health (fitness, wellbeing and freedom from diseases) and increase various forms of, often unconventional commons-oriented, labor. To this end, the application of both advanced technologies and reductions in various demands, including via overall reduced labor time or sufficiency-oriented strategies, are considered to be important by some. On the level of international trade, domestic trade, production and product designs, policies such as for "Produce traceability#Legislative and regulatory matters, digital product passports" have been proposed to link products with environment-related information which could be a requirement for both further measures as well as unfacilitated bottom-up consumer- and business-adaptations.


Research

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. It has been argued that this is a misallocation of resources, as the most urgent puzzle at the current juncture is to work out how to change human behavior to mitigate climate change and which measures could be used how, whereas the natural science of climate change is already well established and there will be decades and centuries to handle adaptation. For instance, a study concluded that forms of personal carbon trading, carbon allowances (carbon credits) could be an effective component of climate change mitigation, with the economic recovery of COVID-19 and new technical capacity having opened a favorable window of opportunity for initial test runs of such in appropriate regions, while many questions remain largely unaddressed. Knowledge transfer, technology transfer, coordination structures, collaborative open innovation, open efficient research and development, non-commercial forms of work and product exchange and inducing maximum efficient investments (not only by market incentives, but also via governments and policy, civil society, and others) could contribute to climate change mitigation.


Population planning

Worldwide population growth is mostly seen as a threat to food security and biodiversity but also considered as a challenge for climate change mitigation. Proposed measures include an improved access to family planning and access of women to education and economic opportunities. Targeting natalistic politics involves cultural, ethical and societal issues. Various religions religious views on birth control, discourage or prohibit some or all forms of birth control. Population size has a vastly different per capita effect on global warming in different countries. In a 2021 paper for ''Sustainability Science'', William J. Ripple, lead author of the World Scientists' Warning to Humanity, World Scientists' Warning to Humanity: A Second Notice, Christopher Wolf and Eileen Crist demonstrate that "human population has been mostly ignored with regard to climate policy" and attribute this to the taboo nature of the issue given its association with population policies of the past, including Compulsory sterilization, forced sterilization campaigns and China's one-child policy. They take a different approach and argue that population policies can both advance social justice (such as by abolishing child marriage, expanding family planning services and reforms that improve education for women and girls) while at the same time mitigating the human impact on the climate and the earth system. They say that while overconsumption by the world's wealthy is responsible for 90% of GHG emissions, which can be redressed through Ecotax, eco-taxes, Carbon price, carbon pricing and other policies, the global human population of 7.7 billion contributes to climate change in myriad ways, including the consumption of natural resources and GHG emissions from transportation.


Lifestyle and behavior

The
IPCC Fifth Assessment Report The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations responsible for advancing knowledge on Attribution of recent climate change, human-induced climate change. It was established in 1988 by the ...
emphasises that behaviour, sustainable lifestyle, lifestyle, and cultural change have a high mitigation potential in some sectors, particularly when complementing technological and structural change. Common recommendations include lowering home heating and cooling usage, burning less gasoline, supporting renewable energy sources, buying local products to reduce transportation and the use of communications technologies such as videoconferencing to reduce Hypermobility (travel), hypermobility.Gössling S, Ceron JP, Dubois G, Hall CM, Gössling IS, Upham P, Earthscan London (2009). Hypermobile travellers. and Implications for Carbon Dioxide Emissions Reduction. In: Climate Change and Aviation: Issues, Challenges and Solutions, London. The chapter:
Chapter 6
''
Other examples would be heating a room less or driving less. In general, higher consumption lifestyles have a greater environmental impact. The sources of emissions have also been shown to be highly unevenly distributed, with 45% of emissions coming from the lifestyles of just 10% of the global population. Several scientific studies have shown that when relatively rich people wish to reduce their carbon footprint, there are a few key actions they can take such as living car-free movement, car-free (2.4 tonnes CO2), avoiding one round-trip transatlantic flight (1.6 tonnes) and eating a plant-based diet (0.8 tonnes). These appear to differ significantly from the popular advice for "greening" one's lifestyle, which seem to fall mostly into the "low-impact" category: Replacing a typical car with a hybrid (0.52 tonnes); Washing clothes in cold water (0.25 tonnes); Recycling (0.21 tonnes); Upgrading light bulbs (0.10 tonnes); etc. The researchers found that public discourse on reducing one's carbon footprint overwhelmingly focuses on low-impact behaviors, and that mention of the high-impact behaviors is almost non-existent in the mainstream media, government publications, school textbooks, etc. Scientists also argue that piecemeal behavioural changes like re-using plastic bags are not a proportionate response to climate change. Though being beneficial, these debates would drive public focus away from the requirement for an energy system change of unprecedented scale to decarbonise rapidly. Moreover, policy measures such as targeted subsidies, eco-tariffs, effective sustainability certificates, legal product information requirements, CO2 pricing, emissions allowances rationing, budget-allocations/labelling, targeted product-range exclusions, advertising bans, and feedback mechanisms are examples of measures that could have a more substantial positive impact consumption behavior than changes exclusively carried out by consumers and could address social issues such as consumers' inhibitive constraints of budgets, awareness and time.


Dietary change

The widespread adoption of a vegetarian diet could cut food-related greenhouse gas emissions by 63% by 2050. Addressing the high methane emissions by cattle, a 2016 study analyzed surcharges of 40% on beef and 20% on milk and suggests that an optimum plan would reduce emissions by 1billion tonnes per year. 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 GHG emissions with nearly 20% of the global carbon footprint. Almost 15% of all anthropogenic GHG emissions has been attributed to the livestock sector alone. The IPCC's summary of the 2019 special report stated that a shift towards plant-based diets would help to mitigate climate change.


Modal shift

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 has made smart mobility part of its European Green Deal and in Smart city, smart cities, smart mobility is also important.


Activism

Environmental organizations take various actions such as Peoples Climate Marches. A major event was the global climate strike in September 2019 organized by Fridays For Future and Earth Strike. The target was to influence the climate action summit organized by the UN on 23 September. According to the organizers four million people participated in the strike on 20 September. In 2019, Extinction Rebellion organized large protests demanding to "reduce carbon emissions to zero by 2025, and create a citizens' assembly to oversee progress", including blocking roads.


Media, education and arts

Media can contribute to climate change mitigation by educating citizens about climate change such as about some of the reasons for mitigation. On the other hand, advertising and journalism also advance the climate emergency in various ways. Content analyses found the share of media coverage of climate change to be relatively small. False balance refers to giving viewers an inaccurate perception of the state of affairs while trying to create the impression of neutral coverage by portraying certain questions as controversial despite there being a consensus of experts and scientists, with uncertainty or controversy being reserved for other, e.g. more specific, issues. Research suggests that the coverage usually does not include scientific content and commonly showed false balance. It has been suggested that the "role of a free press is to inform the people" – particularly solutions journalism, about societal problems of significance and with sufficiently unpoliticized unideological formats, shares of coverage and high quality relevant content that are appropriate. Climate change has been called a niche topic in the media as well as a "cross-cutting issue that needs to be reflected, for example, in reporting on tax reforms, economic policy or new smartphone models" (translated). Journalists could contribute to making the coverage interesting and relevant. With climate change being a "global, complex, and abstract phenomenon", the media is considered to be a highly dependent on source of information and opinion formation about it. Social media as a news source, News on social media may also be relevant to climate change mitigation.


Fiction and culture

While there are some novels of climate fiction that are based on scientific projections of climate change impacts, some observers have wondered why Film industry, cinema appears to "ignore" climate change. Culture – which includes norms, prevailing paradigms of thinking or zeitgeist, lifestyles, art, elements of identity and consumption-patterns – may be an important factor of climate change mitigation. A study suggests that the historical and ongoing "carbon lock-in" is an outcome of the "pervasive failure in industrial, modern societies to imagine desirable ways of living that are neither wedded to the carbon economy nor dependent on narratives of progress reliant on perpetual economic growth" in terms of GDP-growth.


Education systems

Climate change education, Education about climate change and training of skills relevant to mitigation could be important for effective mitigation of climate change. It has been argued that there is a societal need for putting general problem solving skills at the center of education and that too little attention is being paid to real problem‐solving. As economies may partly start to orient towards sustainability, the number of "green jobs" may increase while other jobs are being lost. Such changes may make it more beneficial to Education#Development, develop education systems and establish ways of retraining. Increased expertise and awareness as well as a larger work-force may also facilitate further mitigation. Effectiveness of government regulation, a skilled work force and public awareness may be determinants of "mitigative capacity". Strengthening climate education has been described as a Tipping point (sociology), social tipping intervention that supports and amplifies norms and values and can quickly inspire behavior change among individuals and their cohorts.


Overviews, integration and comparisons of measures

Platforms that aggregated a large number of potential climate change mitigation measures along with estimations of their effectiveness and assessed priority include Drawdown (climate)#Project Drawdown, Project Drawdown. The Web 1.0, non-collaborative science-based website dedicated to the problem of climate change provides one methodological framework and modeling tool to assess impacts of technologies and practices at the global scale. On the website, solutions are incorporated into different areas such as sectors of the economy. Individual climate change mitigation measures can be integrated into comprehensive strategies. Studies – including Feasibility study, feasibility studies and policy studies – have been used to explore how countries could transform for decarbonization. On the global scale, one study developed different broad scenarios of minimal energy requirements for providing decent living standards globally, finding that by 2050 energy use could generally be reduced to 1960 levels. Research activities may help quantify interrelations between challenges of climate change mitigation – like that of
variable renewable energy Variable renewable energy (VRE) or intermittent renewable energy sources (IRES) are renewable energy Renewable energy is energy that is collected from renewable resource File:Global Vegetation.jpg, Global vegetation A renewable resource, ...
– and solutions. For example, comparative analyses of the overall environmental impact assessment, environmental impacts of different solution combinations, of projections-based externality, externalities-data and life-cycle assessments could be used to this end. An interdisciplinary "whole systems theory, system approach" – such as for developing and considering other societal goals as well as, sometimes flexibly, taking complications into account while integrating an otherwise unmanageably large amount of problem domains, synergies, trade-offs, monitoring inputs, modelling results and data – may be important for adequate climate change mitigation.


Shape of mitigation

Climate change mitigation is interconnected with various co-benefits (such as reduced air pollution and associated health benefits) and how it is carried out (in terms of e.g. policymaking) could also determine its impacts on living standards (whether and how inequality and poverty are reduced). Many mitigation measures are associated with new problems which depend on the shape and configuration of the mitigation. For instance, as mining for materials needed for renewable energy production increases threats to conservation areas, some strategic planning that takes such complications into consideration may be needed. There also is research into ways to Solar cell#Recycling, recycle solar panels (including the emerging perovskite solar cells) as recycling solar panels could be important for sustainability, reduce electronic waste and create a source for materials that would otherwise need to be mined. Carbon rationing could have a larger effect on poorer households as "people in the low-income groups may have an above-average energy use, because they live in inefficient homes". However, forms of discourses about the shape of mitigation may "often lead to deadlock or a sense that there are intractable obstacles to taking action".


Tracking and monitoring

Earth observation satellite#Environmental monitoring, Satellites are increasingly being used for locating and measuring greenhouse gas emissions and
deforestation deforestation in 1750-2004 (net loss) showing anthropogenic modification of remaining forest. File:MODIS (2020-08-01).jpg, 300px, Dry seasons, exacerbated by climate change, and the use of slash-and-burn methods for clearing tropical forest ...

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. It has been proposed that if politicians and business leaders know their actions (or inaction) are being recorded for future use, this could have immediate impacts. 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 2020 in the environment and environmental sciences#International goals, 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 reported that of countries responsible for 85% of GHG emissions, only four polities (responsible for 6% of global GHG emissions) – EU, UK, Chile and Costa Rica – have published a detailed official policyplan that describes the steps and ways by which 2030 mitigation targets could be realized. Various further organizations aim to transparently, neutrally and credibly monitor progress of climate change mitigation such as of pledges, goals, initiatives and other developments.


See also


References


General sources


IPCC reports

AR4 Working Group I Report * (pb: ). ** AR4 Working Group III Report * (pb: ). ** ** * ; AR5 Working Group III Report * (pb: )
Fifth Assessment Report – Mitigation of Climate Change
** ;; SR15 Special Report
Global Warming of 1.5 ºC —
** ** ** **


IRENA

: By the International Renewable Energy Agency * * *


Other sources

* * * * * * * * * * * *


Further reading

* Paul Hawken (2021). ''Regeneration: Ending the Climate Crisis in One Generation''. Penguin Books. *National Academies of Sciences, Engineering, and Medicine (2019) ''doi:10.17226/25259, Negative Emissions Technologies and Reliable Sequestration: A Research Agenda.'' * E McGaughey, M Lawrence and Common Wealth,
The Green Recovery Act 2020
, a proposed United Kingdom law, an
pdf
* Bernie Sanders
Green New Deal
(2019) proposal in the United States
Green New Deal for Europe
(2019) Edition II, foreword by Ann Pettifor and Bill McKibben {{Authority control Climate change mitigation, Biogeochemical cycle Biogeography Carbon, Cycle Chemical oceanography Climate change policy Geochemistry Numerical climate and weather models Soil