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Greenhouse gas (GHG) emissions from human activities intensify the
greenhouse effect The greenhouse effect occurs when greenhouse gases in a planet's atmosphere insulate the planet from losing heat to space, raising its surface temperature. Surface heating can happen from an internal heat source (as in the case of Jupiter) or ...
. This contributes to
climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
.
Carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
(), from burning
fossil fuel A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geolog ...
s such as
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...
, oil, and
natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...
, is the main cause of climate change. The largest annual emissions are from China followed by the United States. The United States has higher emissions per capita. The main producers fueling the emissions globally are large oil and gas companies. Emissions from human activities have increased atmospheric carbon dioxide by about 50% over pre-industrial levels. The growing levels of emissions have varied, but have been consistent among all
greenhouse gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
es. Emissions in the 2010s averaged 56 billion tons a year, higher than any decade before. Total cumulative emissions from 1870 to 2022 were 703 (2575 ), of which 484±20 (1773±73 ) from
fossil fuel A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geolog ...
s and industry, and 219±60 (802±220 ) from
land use change Land use is an umbrella term to describe what happens on a parcel of land. It concerns the benefits derived from using the land, and also the land management actions that humans carry out there. The following categories are used for land use: for ...
.
Land-use change Land use is an umbrella term to describe what happens on a parcel of land. It concerns the benefits derived from using the land, and also the land management actions that humans carry out there. The following categories are used for land use: for ...
, such as deforestation, caused about 31% of cumulative emissions over 1870–2022,
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...
32%, oil 24%, and gas 10%. Carbon dioxide is the main greenhouse gas resulting from human activities. It accounts for more than half of warming.
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 abundance of methane on Earth makes ...
(CH4) emissions have almost the same short-term impact.
Nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or factitious air, among others, is a chemical compound, an Nitrogen oxide, oxide of nitrogen with the Chemical formula, formula . At room te ...
(N2O) and fluorinated gases (F-gases) play a lesser role in comparison. Emissions of carbon dioxide, methane and nitrous oxide in 2023 were all higher than ever before.
Electricity generation Electricity generation is the process of generating electric power from sources of primary energy. For electric utility, utilities in the electric power industry, it is the stage prior to its Electricity delivery, delivery (Electric power transm ...
, heat and
transport Transport (in British English) or transportation (in American English) is the intentional Motion, movement of humans, animals, and cargo, goods from one location to another. Mode of transport, Modes of transport include aviation, air, land tr ...
are major emitters; overall energy is responsible for around 73% of emissions.
Deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...
and other changes in land use also emit carbon dioxide and
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...
. The largest source of anthropogenic
methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...
is
agriculture Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...
, closely followed by
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 ...
and
fugitive emissions Fugitive emissions are leaks and other irregular releases of gases or vapors from a pressurized containment – such as appliances, storage tanks, pipelines, wells, or other pieces of equipment – mostly from industrial activities. In addition t ...
from the fossil-fuel industry. The largest agricultural methane source is
livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...
. Agricultural soils emit
nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or factitious air, among others, is a chemical compound, an Nitrogen oxide, oxide of nitrogen with the Chemical formula, formula . At room te ...
partly due to
fertilizer A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...
s. Similarly, fluorinated gases from
refrigerant A refrigerant is a working fluid used in the cooling, heating, or reverse cooling/heating cycles of air conditioning systems and heat pumps, where they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are ...
s play an outsized role in total human emissions. The current -equivalent emission rates averaging 6.6 tonnes per person per year, are well over twice the estimated rate 2.3 tons required to stay within the 2030 Paris Agreement increase of 1.5 °C (2.7 °F) over pre-industrial levels. Annual per capita emissions in the industrialized countries are typically as much as ten times the average in developing countries. The
carbon footprint A carbon footprint (or greenhouse gas footprint) is a calculated value or index that makes it possible to compare the total amount of greenhouse gases that an activity, product, company or country Greenhouse gas emissions, adds to the atmospher ...
(or ''greenhouse gas footprint'') serves as an indicator to compare the amount of greenhouse gases emitted over the entire life cycle from the production of a good or service along the
supply chain A supply chain is a complex logistics system that consists of facilities that convert raw materials into finished products and distribute them to end consumers or end customers, while supply chain management deals with the flow of goods in distri ...
to its final consumption.IPCC, 2022
Annex I: Glossary
an Diemen, R., J.B.R. Matthews, V. Möller, J.S. Fuglestvedt, V. Masson-Delmotte, C. Méndez, A. Reisinger, S. Semenov (eds) In IPCC, 2022
Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
.R. Shukla, J. Skea, R. Slade, A. Al Khourdajie, R. van Diemen, D. McCollum, M. Pathak, S. Some, P. Vyas, R. Fradera, M. Belkacemi, A. Hasija, G. Lisboa, S. Luz, J. Malley, (eds.) Cambridge University Press, Cambridge, UK and New York, NY, USA. doi: 10.1017/9781009157926.020
Carbon accounting Carbon accounting (or greenhouse gas accounting) is a framework of methods to measure and track how much greenhouse gas (GHG) an organization emits. It can also be used to track projects or actions to reduce emissions in sectors such as forest ...
(or greenhouse gas accounting) is a framework of methods to measure and track how much
greenhouse gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
an organization emits.


Relevance for greenhouse effect and global warming


Overview of main sources


Relevant greenhouse gases

The major anthropogenic (human origin) sources of greenhouse gases are carbon dioxide (), nitrous oxide (), methane and three groups of fluorinated gases (
sulfur hexafluoride Sulfur hexafluoride or sulphur hexafluoride ( British spelling) is an inorganic compound with the formula SF6. It is a colorless, odorless, non-flammable, and non-toxic gas. has an octahedral geometry, consisting of six fluorine atoms attache ...
(),
hydrofluorocarbons Hydrofluorocarbons (HFCs) are synthetic 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 condit ...
(HFCs) and
perfluorocarbons Fluorocarbons are chemical compounds with carbon-fluorine bonds. Compounds that contain many C-F bonds often have distinctive properties, e.g., enhanced stability, volatility, and hydrophobicity. Several fluorocarbons and their derivatives are ...
(PFCs, sulphur hexafluoride (SF6), and nitrogen trifluoride (NF3)). Though the
greenhouse effect The greenhouse effect occurs when greenhouse gases in a planet's atmosphere insulate the planet from losing heat to space, raising its surface temperature. Surface heating can happen from an internal heat source (as in the case of Jupiter) or ...
is heavily driven by
water vapor Water vapor, water vapour, or aqueous vapor is the gaseous phase of Properties of water, water. It is one Phase (matter), state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from th ...
, human emissions of water vapor are not a significant contributor to warming. Although CFCs are greenhouse gases, they are regulated by the
Montreal Protocol The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 ...
which was motivated by CFCs' contribution to
ozone depletion Ozone depletion consists of two related events observed since the late 1970s: a lowered total amount of ozone in Earth, Earth's upper atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar ...
rather than by their contribution to global warming. Ozone depletion has only a minor role in greenhouse warming, though the two processes are sometimes confused in the media. In 2016, negotiators from over 170 nations meeting at the summit 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, its first director, after the Declaration of the United Nati ...
reached a legally binding accord to phase out
hydrofluorocarbons Hydrofluorocarbons (HFCs) are synthetic 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 condit ...
(HFCs) in the
Kigali Amendment The Kigali Amendment to the Montreal Protocol is an international agreement to gradually reduce the consumption and production of hydrofluorocarbons (HFCs). It is a legally binding agreement designed to create rights and obligations in internati ...
to the
Montreal Protocol The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 ...
. The use of CFC-12 (except some essential uses) has been phased out due to its ozone depleting properties. The phasing-out of less active HCFC-compounds will be completed in 2030.


Human activities

Starting about 1750, industrial activity powered by fossil fuels began to significantly increase the concentration of carbon dioxide and other greenhouse gases. Emissions have grown rapidly since about 1950 with ongoing expansions in global population and economic activity following World War II. As of 2021, measured atmospheric concentrations of carbon dioxide were almost 50% higher than pre-industrial levels. The main sources of greenhouse gases due to human activity (also called ''carbon sources'') are: * Burning fossil fuels: Burning oil, coal and gas is estimated to have emitted 37.4 billion tonnes of -eq in 2023. The largest single source is coal-fired power stations, with 20% of greenhouse gases (GHG) as of 2021. * Land use change (mainly deforestation in the tropics) accounts for about a quarter of total anthropogenic GHG emissions. * Livestock enteric fermentation and manure management, paddy
rice Rice is a cereal grain and in its Domestication, domesticated form is the staple food of over half of the world's population, particularly in Asia and Africa. Rice is the seed of the grass species ''Oryza sativa'' (Asian rice)—or, much l ...
farming, land use and
wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...
changes, human-made lakes, pipeline losses, and covered vented landfill emissions leading to higher methane atmospheric concentrations. Many of the newer style fully vented septic systems that enhance and target the fermentation process also are sources of
atmospheric methane Atmospheric methane is the methane present in Earth's atmosphere. The concentration of atmospheric methane is increasing due to methane emissions, and is causing climate change. Methane is one of the most potent greenhouse gases. Methane's radiati ...
. * Use of
chlorofluorocarbons Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F). They are produced as volatile derivatives of methane, ethane, ...
(CFCs) in
refrigeration Refrigeration is any of various types of cooling of a space, substance, or system to lower and/or maintain its temperature below the ambient one (while the removed heat is ejected to a place of higher temperature).IIR International Dictionary of ...
systems, and use of CFCs and halons in
fire suppression Fire suppression may refer to: * Firefighting * Fire suppression systems * Wildfire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts depend on many factors such as the availabl ...
systems and manufacturing processes. * Agricultural soils emit nitrous oxide (N2O) partly due to application of
fertilizer A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...
s. * The largest source of anthropogenic
methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...
is
agriculture Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...
, closely followed by
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 ...
and
fugitive emissions Fugitive emissions are leaks and other irregular releases of gases or vapors from a pressurized containment – such as appliances, storage tanks, pipelines, wells, or other pieces of equipment – mostly from industrial activities. In addition t ...
from the fossil-fuel industry. The largest agricultural methane source is
livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...
. Cattle (raised for both beef and milk, as well as for inedible outputs like manure and draft power) are the animal species responsible for the most emissions, representing about 65% of the livestock sector's emissions.


Global estimates

Global greenhouse gas emissions are about 50 Gt per year and for 2019 have been estimated at 57 Gt eq including 5 Gt due to land use change. In 2019, approximately 34% 0 Gt-eqof total net anthropogenic GHG emissions came from the energy supply sector, 24% 4 Gt-eqfrom industry, 22% 3 Gt-eqfrom agriculture, forestry and other land use (AFOLU), 15% .7 Gt-eqfrom transport and 6% .3 Gt-eqfrom buildings. The current -equivalent emission rates averaging 6.6 tonnes per person per year, are well over twice the estimated rate 2.3 tons required to stay within the 2030 Paris Agreement increase of 1.5 °C (2.7 °F) over pre-industrial levels. While cities are sometimes considered to be disproportionate contributors to emissions, per-capita emissions tend to be lower for cities than the averages in their countries. A 2017 survey of corporations responsible for global emissions found that 100 companies were responsible for 71% of global direct and indirect emissions, and that state-owned companies were responsible for 59% of their emissions. China is, by a significant margin, Asia's and the world's largest emitter: it emits nearly 10 billion tonnes each year, more than one-quarter of global emissions. Other countries with fast growing emissions are
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...
, Iran, and Australia (which apart from the oil rich Persian Gulf states, now has the highest per capita emission rate in the world). On the other hand, annual per capita emissions of the EU-15 and the US are gradually decreasing over time. Emissions in Russia and Ukraine have decreased fastest since 1990 due to economic restructuring in these countries. 2015 was the first year to see both total global economic growth and a reduction of carbon emissions.


High income countries compared to low income countries

Annual per capita emissions in the industrialized countries are typically as much as ten times the average in developing countries. Due to China's fast economic development, its annual per capita emissions are quickly approaching the levels of those in the Annex I group of the Kyoto Protocol (i.e., the developed countries excluding the US). Africa and South America are both fairly small emitters, accounting for 3-4% of global emissions each. Both have emissions almost equal to international aviation and shipping.


Calculations and reporting


Variables

There are several ways of measuring greenhouse gas emissions. Some variables that have been reported include: * Definition of measurement boundaries: Emissions can be attributed geographically, to the area where they were emitted (the territory principle) or by the activity principle to the territory that produced the emissions. These two principles result in different totals when measuring, for example, electricity importation from one country to another, or emissions at an international airport. * Time horizon of different gases: The contribution of given greenhouse gas is reported as a equivalent. The calculation to determine this takes into account how long that gas remains in the atmosphere. This is not always known accurately and calculations must be regularly updated to reflect new information. * The measurement protocol itself: This may be via direct measurement or estimation. The four main methods are the emission factor-based method, mass balance method, predictive emissions monitoring systems, and
continuous emissions monitoring system Continuous emission monitoring systems (CEMS) are used as a tool to monitor the effluent gas streams resulting from combustion in industrial processes. CEMS can measure flue gas for oxygen, carbon monoxide and carbon dioxide to provide information ...
s. These methods differ in accuracy, cost, and usability. Public information from
space-based measurements of carbon dioxide Space-based measurements of carbon dioxide () are used to help answer questions about Earth's carbon cycle. There are a variety of active and planned instruments for measuring carbon dioxide in Earth's atmosphere from space. The first satell ...
by
Climate Trace Climate TRACE (Tracking Real-Time Atmospheric Carbon Emissions) is an independent group which monitors and publishes greenhouse gas emissions. It launched in 2021 before COP26, and improves monitoring, reporting and verification (MRV) of both ...
is expected to reveal individual large plants before the
2021 United Nations Climate Change Conference The 2021 United Nations Climate Change Conference, more commonly referred to as COP26, was the 26th United Nations Climate Change conference, held at the SEC Centre in Glasgow, Scotland Scotland is a Countries of the United Kingdom, coun ...
. These measures are sometimes used by countries to assert various policy/ethical positions on climate change.The use of different measures leads to a lack of comparability, which is problematic when monitoring progress towards targets. There are arguments for the adoption of a common measurement tool, or at least the development of communication between different tools.


Reporting

Emissions may be tracked over long time periods, known as historical or cumulative emissions measurements. Cumulative emissions provide some indicators of what is responsible for greenhouse gas atmospheric concentration build-up.


National accounts balance

The national accounts balance tracks emissions based on the difference between a country's exports and imports. For many richer nations, the balance is negative because more goods are imported than they are exported. This result is mostly due to the fact that it is cheaper to produce goods outside of developed countries, leading developed countries to become increasingly dependent on services and not goods. A positive account balance would mean that more production was occurring within a country, so more operational factories would increase carbon emission levels. Emissions may also be measured across shorter time periods. Emissions changes may, for example, be measured against the base year of 1990. 1990 was used in the
United Nations Framework Convention on Climate Change The United Nations Framework Convention on Climate Change (UNFCCC) is the UN process for negotiating an agreement to limit dangerous climate change. It is an international treaty among countries to combat "dangerous human interference with th ...
(UNFCCC) as the base year for emissions, and is also used in the
Kyoto Protocol The was an international treaty which extended the 1992 United Nations Framework Convention on Climate Change (UNFCCC) that commits state parties to reduce greenhouse gas emissions, based on the scientific consensus that global warming is oc ...
(some gases are also measured from the year 1995). A country's emissions may also be reported as a proportion of global emissions for a particular year. Another measurement is of per capita emissions. This divides a country's total annual emissions by its mid-year population. Per capita emissions may be based on historical or annual emissions.


Embedded emissions

One way of attributing greenhouse gas emissions is to measure the embedded emissions (also referred to as "embodied emissions") of goods that are being consumed. Emissions are usually measured according to production, rather than consumption. For example, in the main international
treaty A treaty is a formal, legally binding written agreement between sovereign states and/or international organizations that is governed by international law. A treaty may also be known as an international agreement, protocol, covenant, convention ...
on climate change (the UNFCCC), countries report on emissions produced within their borders, e.g., the emissions produced from burning fossil fuels. Under a production-based accounting of emissions, embedded emissions on imported goods are attributed to the exporting, rather than the importing, country. Under a consumption-based accounting of emissions, embedded emissions on imported goods are attributed to the importing country, rather than the exporting, country. A substantial proportion of emissions is traded internationally. The net effect of trade was to export emissions from China and other emerging markets to consumers in the US, Japan, and Western Europe.


Carbon footprint


Emission intensity

Emission intensity is a ratio between greenhouse gas emissions and another metric, e.g., gross domestic product (GDP) or energy use. The terms "carbon intensity" and " emissions intensity" are also sometimes used. Emission intensities may be calculated using market exchange rates (MER) or
purchasing power parity Purchasing power parity (PPP) is a measure of the price of specific goods in different countries and is used to compare the absolute purchasing power of the countries' currency, currencies. PPP is effectively the ratio of the price of a market bask ...
(PPP).


Example tools and websites

Carbon accounting Carbon accounting (or greenhouse gas accounting) is a framework of methods to measure and track how much greenhouse gas (GHG) an organization emits. It can also be used to track projects or actions to reduce emissions in sectors such as forest ...
(or greenhouse gas accounting) is a framework of methods to measure and track how much greenhouse gas an organization emits.


Climate TRACE


Historical trends


Cumulative and historical emissions

Cumulative anthropogenic (i.e., human-emitted) emissions of from fossil fuel use are a major cause of
global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...
, and give some indication of which countries have contributed most to human-induced climate change. In particular, stays in the atmosphere for at least 150 years and up to 1000 years, whilst methane disappears within a decade or so, and nitrous oxides last about 100 years. The graph gives some indication of which regions have contributed most to human-induced climate change. When these numbers are calculated per capita cumulative emissions based on then-current population the situation is shown even more clearly. The ratio in per capita emissions between industrialized countries and developing countries was estimated at more than 10 to 1. Non-
OECD The Organisation for Economic Co-operation and Development (OECD; , OCDE) is an international organization, intergovernmental organization with 38 member countries, founded in 1961 to stimulate economic progress and international trade, wor ...
countries accounted for 42% of cumulative energy-related emissions between 1890 and 2007. Over this time period, the US accounted for 28% of emissions; the EU, 23%; Japan, 4%; other OECD countries 5%; Russia, 11%; China, 9%; India, 3%; and the rest of the world, 18%.The European Commission adopted a set of legislative proposals targeting a reduction of the emissions by 55% by 2030. Overall, developed countries accounted for 83.8% of industrial emissions over this time period, and 67.8% of total emissions. Developing countries accounted for industrial emissions of 16.2% over this time period, and 32.2% of total emissions. However, what becomes clear when we look at emissions across the world today is that the countries with the highest emissions over history are not always the biggest emitters today. For example, in 2017, the UK accounted for just 1% of global emissions. In comparison, humans have emitted more greenhouse gases than the Chicxulub meteorite impact event which caused the
extinction of the dinosaurs Extinction is the termination of an organism by the death of its last member. A taxon may become functionally extinct before the death of its last member if it loses the capacity to reproduce and recover. As a species' potential range may be ...
. Transport, together with
electricity generation Electricity generation is the process of generating electric power from sources of primary energy. For electric utility, utilities in the electric power industry, it is the stage prior to its Electricity delivery, delivery (Electric power transm ...
, is the major source of greenhouse gas emissions in the EU. Greenhouse gas emissions from the transportation sector continue to rise, in contrast to power generation and nearly all other sectors. Since 1990, transportation emissions have increased by 30%. The transportation sector accounts for around 70% of these emissions. The majority of these emissions are caused by passenger
vehicle A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered land vehicle, human-powered vehicles (e.g. bicycles, tricycles, velo ...
s and vans. Road travel is the first major source of greenhouse gas emissions from transportation, followed by aircraft and maritime. Waterborne transportation is still the least carbon-intensive mode of transportation on average, and it is an essential link in
sustainable Sustainability is a social goal for people to co-exist on Earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability usually has three dimensions (or pillars): env ...
multimodal freight supply chains. Buildings, like industry, are directly responsible for around one-fifth of greenhouse gas emissions, primarily from
space heating A heating system is a mechanism designed to regulate and maintain a desired temperature within a space by utilizing thermal energy. It is a fundamental component of Heating, Ventilation, and Air Conditioning (HVAC) systems, providing warmth to resi ...
and hot water consumption. When combined with power consumption within buildings, this figure climbs to more than one-third. Within the EU, the
agricultural sector Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created f ...
presently accounts for roughly 10% of total greenhouse gas emissions, with methane from livestock accounting for slightly more than half of 10%. Estimates of total emissions do include biotic carbon emissions, mainly from deforestation. Including biotic emissions brings about the same controversy mentioned earlier regarding carbon sinks and land-use change. The actual calculation of net emissions is very complex, and is affected by how carbon sinks are allocated between regions and the dynamics of the
climate system Earth's climate system is a complex system with five interacting components: the Atmosphere of Earth, atmosphere (air), the hydrosphere (water), the cryosphere (ice and permafrost), the lithosphere (earth's upper rocky layer) and the biosphere ( ...
. The graphic shows the logarithm of 1850–2019 fossil fuel emissions; natural log on left, actual value of Gigatons per year on right. Although emissions increased during the 170-year period by about 3% per year overall, intervals of distinctly different growth rates (broken at 1913, 1945, and 1973) can be detected. The regression lines suggest that emissions can rapidly shift from one growth regime to another and then persist for long periods of time. The most recent drop in emissions growth – by almost 3 percentage points – was at about the time of the
1970s energy crisis The 1970s energy crisis occurred when the Western world, particularly the United States, Canada, Western Europe, Australia, and New Zealand, faced substantial petroleum shortages as well as elevated prices. The two worst crises of this period wer ...
. Percent changes per year were estimated by piecewise linear regression on the log data and are shown on the plot; the data are from The Integrated Carbon Observation system.


Changes since a particular base year

The sharp acceleration in emissions since 2000 to more than a 3% increase per year (more than 2 ppm per year) from 1.1% per year during the 1990s is attributable to the lapse of formerly declining trends in
carbon intensity Carbon () is a chemical element; it has symbol C and atomic number 6. It is nonmetallic and tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to grou ...
of both developing and developed nations. China was responsible for most of global growth in emissions during this period. Localised plummeting emissions associated with the collapse of the Soviet Union have been followed by slow emissions growth in this region due to more
efficient energy use Efficient energy use, or energy efficiency, is the process of reducing the amount of energy required to provide products and services. There are many technologies and methods available that are more energy efficient than conventional systems. For ...
, made necessary by the increasing proportion of it that is exported. In comparison, methane has not increased appreciably, and by 0.25% y−1. Using different base years for measuring emissions has an effect on estimates of national contributions to global warming. This can be calculated by dividing a country's highest contribution to global warming starting from a particular base year, by that country's minimum contribution to global warming starting from a particular base year. Choosing between base years of 1750, 1900, 1950, and 1990 has a significant effect for most countries.


Data from Global Carbon Project

The Global Carbon Project continuously releases data about emissions, budget and concentration.


Emissions by type of greenhouse gas

Carbon dioxide () is the dominant emitted greenhouse gas, while methane () emissions almost have the same short-term impact. Nitrous oxide (N2O) and fluorinated gases (F-gases) play a lesser role in comparison. Greenhouse gas emissions are measured in equivalents determined by their
global warming potential Global warming potential (GWP) is a measure of how much heat a greenhouse gas traps in the atmosphere over a specific time period, relative to carbon dioxide (). It is expressed as a multiple of warming caused by the same mass of carbon dioxide ( ...
(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, hydrofluorocarbons (HFCs), tropospheric ozone and
black carbon Black carbon (BC) is the light-absorbing refractory form of Chemical_element, elemental carbon remaining after pyrolysis (e.g., charcoal) or produced by incomplete combustion (e.g., soot). Tihomir Novakov originated the term black carbon in ...
persist in the atmosphere for a period ranging from days to 15 years; whereas carbon dioxide 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. Greenhouse gas 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 a measure of how much heat a greenhouse gas traps in the atmosphere over a specific time period, relative to carbon dioxide (). It is expressed as a multiple of warming caused by the same mass of carbon dioxide ( ...
from IPCC-AR4
While mitigation measures for decarbonization are essential on the longer term, they could result in weak near-term warming because sources of carbon emissions often also co-emit
air pollution Air pollution is the presence of substances in the Atmosphere of Earth, air that are harmful to humans, other living beings or the environment. Pollutants can be Gas, gases like Ground-level ozone, ozone or nitrogen oxides or small particles li ...
. Hence, pairing measures that target carbon dioxide with measures targeting non- pollutants – short-lived climate pollutants, which have faster effects on the climate, is essential for climate goals.


Carbon dioxide ()

* Fossil fuel (use for energy generation, transport, heating and machinery in industrial plants): oil,
gas Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...
and
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...
(89%) are the major driver of anthropogenic global warming with annual emissions of 35.6 Gt in 2019.Olivier J.G.J. and Peters J.A.H.W. (2020)
Trends in global and total greenhouse gas emissions: 2020 report

PBL Netherlands
Environmental Assessment Agency, The Hague.
*
Cement A cement is a binder, a chemical substance used for construction that 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 ( aggregate) together. Cement mi ...
production (burning of fossil fuels) (4%) is estimated at 1.42 Gt * Land-use change (LUC) is the imbalance of
deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...
and
reforestation Reforestation is the practice of restoring previously existing forests and woodlands that have been destroyed or damaged. The prior forest destruction might have happened through deforestation, clearcutting or wildfires. Three important purpose ...
. Estimations are very uncertain at 4.5 Gt.
Wildfire A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a ...
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 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%) (emissions due to losses during production and transport) account for most of the methane emissions including coal mining (12% of methane total), gas distribution and leakages (11%) as well as gas venting 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 Industrial wastewater treatment describes the processes used for treating wastewater that is produced by industries as an undesirable by-product. After treatment, the treated industrial wastewater (or effluent) may be reused or released to a s ...
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 Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the absence of oxygen. The process is used for industrial or domestic purposes to manage waste or to produce fuels. Much of the fermen ...
of organic material produces methane.


Nitrous oxide ()

N2O has a high GWP and significant Ozone Depleting Potential. It is estimated that the global warming potential of N2O over 100 years is 265 times greater than . For N2O, a reduction of more than 50% would be required for a stabilization. Most emissions (56%) of nitrous oxide comes from agriculture, especially meat production: cattle (droppings on pasture), fertilizers, animal manure.Further contributions come from combustion of fossil fuels (18%) and
biofuel Biofuel is a fuel that is produced over a short time span from Biomass (energy), biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricu ...
s as well as industrial production of
adipic acid Adipic acid or hexanedioic acid is the organic compound with the formula C6H10O4. It a white crystalline powder at standard temperature and pressure. From an industrial perspective, it is the most important dicarboxylic acid at about 2.5 billion ...
and
nitric acid Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...
.


F-gases

Fluorinated gases include
hydrofluorocarbons Hydrofluorocarbons (HFCs) are synthetic 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 condit ...
(HFC), perfluorocarbons (PFC),
sulfur hexafluoride Sulfur hexafluoride or sulphur hexafluoride ( British spelling) is an inorganic compound with the formula SF6. It is a colorless, odorless, non-flammable, and non-toxic gas. has an octahedral geometry, consisting of six fluorine atoms attache ...
(SF6), and
nitrogen trifluoride Nitrogen trifluoride is the inorganic compound with the formula (). It is a colorless, non-flammable, toxic gas with a slightly musty odor. In contrast with ammonia, it is nonbasic. It finds increasing use within the manufacturing of flat-panel ...
(NF3). They are used by switchgear in the power sector, semiconductor manufacture, aluminum production and a largely unknown source of SF6. Continued phase down of manufacture and use of HFCs under the
Kigali Amendment The Kigali Amendment to the Montreal Protocol is an international agreement to gradually reduce the consumption and production of hydrofluorocarbons (HFCs). It is a legally binding agreement designed to create rights and obligations in internati ...
to the Montreal Protocol will help reduce HFC emissions and concurrently improve the energy efficiency of appliances that use HFCs like air conditioners, freezers and other refrigeration devices.


Hydrogen

Hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...
leakages contribute to indirect global warming. When hydrogen is oxidized in the atmosphere, the result is an increase in concentrations of greenhouse gases in both the troposphere and the stratosphere. Hydrogen can leak from
hydrogen production Hydrogen gas is produced by several industrial methods. Nearly all of the world's current supply of hydrogen is created from fossil fuels. Article in press. Most hydrogen is ''gray hydrogen'' made through steam methane reforming. In this process, ...
facilities as well as any infrastructure in which hydrogen is transported, stored, or consumed.


Black carbon

Black carbon Black carbon (BC) is the light-absorbing refractory form of Chemical_element, elemental carbon remaining after pyrolysis (e.g., charcoal) or produced by incomplete combustion (e.g., soot). Tihomir Novakov originated the term black carbon in ...
is formed through the incomplete combustion of fossil fuels,
biofuel Biofuel is a fuel that is produced over a short time span from Biomass (energy), biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricu ...
, and
biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...
. It is not a greenhouse gas but a
climate forcing Radiative forcing (or climate forcing) is a concept used to quantify a change to the Earth's energy budget, balance of energy flowing through a planetary atmosphere. Various factors contribute to this change in energy balance, such as concentration ...
agent. Black carbon can absorb sunlight and reduce
albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
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, and minimizing open burning of biomass.


Emissions by sector

Global greenhouse gas emissions can be attributed to different sectors of the economy. This provides a picture of the varying contributions of different types of economic activity to climate change, and helps in understanding the changes required to
mitigate climate change Climate change mitigation (or decarbonisation) is action to limit the greenhouse gases in the atmosphere that cause climate change. Climate change mitigation actions include energy conservation, conserving energy and Fossil fuel phase-out, repl ...
. Greenhouse gas emissions can be divided into those that arise from the combustion of fuels to produce energy, and those generated by other processes. Around two thirds of greenhouse gas emissions arise from the combustion of fuels. Energy may be produced at the point of
consumption Consumption may refer to: * Eating *Resource consumption *Tuberculosis, an infectious disease, historically known as consumption * Consumer (food chain), receipt of energy by consuming other organisms * Consumption (economics), the purchasing of n ...
, or by a generator for consumption by others. Thus emissions arising from energy production may be categorized according to where they are emitted, or where the resulting energy is consumed. If emissions are attributed at the point of production, then electricity generators contribute about 25% of global greenhouse gas emissions. If these emissions are attributed to the final consumer then 24% of total emissions arise from manufacturing and construction, 17% from transportation, 11% from domestic consumers, and 7% from commercial consumers. Around 4% of emissions arise from the energy consumed by the energy and fuel industry itself. The remaining third of emissions arise from processes other than energy production. 12% of total emissions arise from agriculture, 7% from land use change and forestry, 6% from industrial processes, and 3% from waste.


Electricity generation

Coal-fired power station A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide there are about 2,500 coal-fired power stations, on average capable of generating a gigawatt each. They generate ...
s are the single largest emitter, with over 20% of global greenhouse gas emissions in 2018. Although much less polluting than coal plants, natural
gas-fired power plant A gas-fired power plant, sometimes referred to as gas-fired power station, natural gas power plant, or methane gas power plant, is a thermal power station that burns natural gas to generate electricity. Gas-fired power plants generate almost a ...
s are also major emitters, taking electricity generation as a whole over 25% in 2018. Notably, just 5% of the world's power plants account for almost three-quarters of carbon emissions from electricity generation, based on an inventory of more than 29,000 fossil-fuel power plants across 221 countries. In the 2022 IPCC report, it is noted that providing modern energy services universally would only increase greenhouse gas emissions by a few percent at most. This slight increase means that the additional energy demand that comes from supporting decent living standards for all would be far lower than current average energy consumption. In March 2024, the
International Energy Agency The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organization, established in 1974, that provides policy recommendations, analysis and data on the global energy sector. The 31 member countries and 13 associatio ...
(IEA) reported that in 2023, global emissions from energy sources increased by 1.1%, rising by 410 million tonnes to a record 37.4 billion tonnes, primarily due to coal. Drought-related decreases in hydropower contributed to a 170 million tonne rise in emissions, which would have otherwise led to a decrease in the electricity sector's emissions. The implementation of
clean energy Energy is sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs." Definitions of sustainable energy usually look at its effects on the environment, the economy, and s ...
technologies like
solar Solar may refer to: Astronomy * Of or relating to the Sun ** Solar telescope, a special purpose telescope used to observe the Sun ** A device that utilizes solar energy (e.g. "solar panels") ** Solar calendar, a calendar whose dates indicate t ...
,
wind Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heatin ...
, nuclear,
heat pump A heat pump is a device that uses electricity to transfer heat from a colder place to a warmer place. Specifically, the heat pump transfers thermal energy using a heat pump and refrigeration cycle, cooling the cool space and warming the warm s ...
s, and
electric vehicle An electric vehicle (EV) is a motor vehicle whose propulsion is powered fully or mostly by electricity. EVs encompass a wide range of transportation modes, including road vehicle, road and rail vehicles, electric boats and Submersible, submer ...
s since 2019 has significantly tempered emissions growth, which would have been threefold without these technologies.


Agriculture, forestry and land use


Agriculture


= Deforestation

= Deforestation is a major source of greenhouse gas emissions. A study shows annual carbon emissions (or carbon loss) from tropical deforestation have doubled during the last two decades and continue to increase. (0.97 ±0.16 PgC per year in 2001–2005 to 1.99 ±0.13 PgC per year in 2015–2019)


= Land-use change

= Land-use change, e.g., the clearing of forests for agricultural use, can affect the concentration of greenhouse gases in the atmosphere by altering how much carbon flows out of the atmosphere into
carbon sink A carbon sink is a natural or artificial carbon sequestration process that "removes a  greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere". These sinks form an important part of the natural carbon cycle. An overar ...
s. Accounting for land-use change can be understood as an attempt to measure "net" emissions, i.e., gross emissions from all sources minus the removal of emissions from the atmosphere by carbon sinks. There are substantial uncertainties in the measurement of net carbon emissions. Additionally, there is controversy over how carbon sinks should be allocated between different regions and over time. For instance, concentrating on more recent changes in carbon sinks is likely to favour those regions that have deforested earlier, e.g., Europe. In 1997, human-caused Indonesian peat fires were estimated to have released between 13% and 40% of the average annual global carbon emissions caused by the burning of
fossil fuels A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geologica ...
.


Transport of people and goods

Transportation accounts for 15% of emissions worldwide. Over a quarter of global transport emissions are from road freight, so many countries are further restricting
truck A truck or lorry is a motor vehicle designed to transport freight, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construct ...
emissions to help limit climate change.
Maritime transport Maritime transport (or ocean transport) or more generally waterborne transport, is the transport of people (passengers or goods (cargo) via waterways. Freight transport by watercraft has been widely used throughout recorded history, as it pr ...
accounts for 3.5% to 4% of all greenhouse gas emissions, primarily carbon dioxide. In 2022, the shipping industry's 3% of global greenhouse gas emissions made it "the sixth largest greenhouse gas emitter worldwide, ranking between Japan and Germany."


Aviation

Jet airliners contribute to climate change by emitting carbon dioxide (), nitrogen oxides, contrails and particulates.In 2018, global commercial operations generated 2.4% of all emissions. In 2020, approximately 3.5% of the overall human impacts on climate are from the aviation sector. The impact of the sector on climate in the last 20 years had doubled, but the part of the contribution of the sector in comparison to other sectors did not change because other sectors grew as well. Some representative figures for average direct emissions (not accounting for high-altitude radiative effects) of airliners expressed as and equivalent per passenger kilometer: * Domestic, short distance, less than : 257 g/km or 259 g/km (14.7 oz/mile) e * Long-distance flights: 113 g/km or 114 g/km (6.5 oz/mile) e


Buildings and construction

In 2018, manufacturing construction materials and maintaining buildings accounted for 39% of carbon dioxide emissions from energy and process-related emissions. Manufacture of glass, cement, and steel accounted for 11% of energy and process-related emissions. Because building construction is a significant investment, more than two-thirds of buildings in existence will still exist in 2050.
Retrofitting Retrofitting is the addition of new technology or features to older systems. Retrofits can happen for a number of reasons, for example with big capital expenditures like naval vessels, military equipment or manufacturing plants, businesses or go ...
existing buildings to become more efficient will be necessary to meet the targets of the Paris Agreement; it will be insufficient to only apply low-emission standards to new construction. Buildings that produce as much energy as they consume are called
zero-energy building A Zero-Energy Building (ZEB), also known as a Net Zero-Energy (NZE) building, is a building with net zero energy consumption, meaning the total amount of energy used by the building on an annual basis is equal to the amount of renewable energy c ...
s, while buildings that produce more than they consume are energy-plus. Low-energy buildings are designed to be highly efficient with low total energy consumption and carbon emissions—a popular type is the
passive house Passive house () is a voluntary standard for energy efficiency in a building that reduces the building's carbon footprint. Conforming to these standards results in ultra-low energy buildings that require less energy for space heating or co ...
. The construction industry has seen marked advances in building performance and energy efficiency over recent decades. Green building practices that avoid emissions or capture the carbon already present in the environment, allow for reduced footprint of the construction industry, for example, use of hempcrete, cellulose fiber insulation, and
landscaping Landscaping refers to any activity that modifies the visible features of an area of land, including the following: # Living elements, such as flora or fauna; or what is commonly called gardening, the art and craft of growing plants with a goal ...
. In 2019, the building sector was responsible for 12 Gt-eq emissions. More than 95% of these emissions were carbon, and the remaining 5% were , , and halocarbon. The largest contributor to building sector emissions (49% of total) is the production of electricity for use in buildings. Of global building sector GHG emissions, 28% are produced during the manufacturing process of building materials such as
steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...
,
cement A cement is a binder, a chemical substance used for construction that 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 ( aggregate) together. Cement mi ...
(a key component of
concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...
), and glass. The conventional process inherently related to the production of steel and cement results in large amounts of CO2 emitted. For example, the production of steel in 2018 was responsible for 7 to 9% of the global CO2 emissions. The remaining 23% of global building sector GHG emissions are produced directly on site during building operations.


Embodied carbon emissions in construction sector

Embodied carbon emissions One way of attributing greenhouse gas emissions is to measure the embedded emissions of goods that are being consumed (also referred to as "embodied emissions", "embodied carbon emissions", or "embodied carbon"). This is different from the quest ...
, or upfront carbon emissions (UCE), are the result of creating and maintaining the materials that form a building. As of 2018, "Embodied carbon is responsible 11% of global greenhouse gas emissions and 28% of global building sector emissions ... Embodied carbon will be responsible for almost half of total new construction emissions between now and 2050." GHG emissions which are produced during the mining, processing, manufacturing, transportation and installation of building materials are referred to as the ''embodied carbon of a material''. The embodied carbon of a construction project can be reduced by using low-carbon materials for building structures and finishes, reducing demolition, and reusing buildings and construction materials whenever possible.


Industrial processes

Secunda CTL Secunda CTL is a synthetic fuel plant owned by Sasol at Secunda, Mpumalanga in South Africa. It uses coal liquefaction to produce petroleum-like synthetic crude oil from coal. The process used by Sasol is based on the Fischer–Tropsch proces ...
is the world's largest single emitter, at 56.5 million tonnes a year.


Mining

Flaring and venting of
natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...
in oil wells is a significant source of greenhouse gas emissions. Its contribution to greenhouse gases has declined by three-quarters in absolute terms since a peak in the 1970s of approximately 110 million metric tons/year, and in 2004 accounted for about 1/2 of one percent of all anthropogenic carbon dioxide emissions. The
World Bank The World Bank is an international financial institution that provides loans and Grant (money), grants to the governments of Least developed countries, low- and Developing country, middle-income countries for the purposes of economic development ...
estimates that 134 billion cubic meters of natural gas are flared or vented annually (2010 datum), an amount equivalent to the combined annual gas consumption of
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
and
France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
or enough to supply the entire world with gas for 16 days. This flaring is highly concentrated: 10 countries account for 70% of emissions, and twenty for 85%.


Steel and aluminum

Steel and aluminum are key economic sectors where is produced. According to a 2013 study, "in 2004, the steel industry along emits about 590M tons of , which accounts for 5.2% of the global anthropogenic GHG emissions. emitted from steel production primarily comes from energy consumption of fossil fuel as well as the use of
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
to purify
iron oxide An iron oxide is a chemical compound composed of iron and oxygen. Several iron oxides are recognized. Often they are non-stoichiometric. Ferric oxyhydroxides are a related class of compounds, perhaps the best known of which is rust. Iron ...
s." More recent estimates suggest that global steel production emitted around 2,280 million tons of CO₂ in 2017, indicating the scale has increased significantly. A 2022 study found that across bulk material sectors—steel, aluminum, cement, and paper—total emissions reached approximately 8.4 billion tons of CO₂ equivalent.


Plastics

Plastics are produced mainly from fossil fuels. It was estimated that between 3% and 4% of global GHG emissions are associated with plastics' life cycles. The EPA estimates as many as five mass units of carbon dioxide are emitted for each mass unit of
polyethylene terephthalate Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in synthetic fibre, fibres for clothing, packaging, conta ...
(PET) produced—the type of plastic most commonly used for beverage bottles, the transportation produce greenhouse gases also.
Plastic waste Plastic pollution is the accumulation of plastic objects and particles (e.g. plastic bottles, bags and microbeads) in the Earth's environment that adversely affects humans, wildlife and their habitat. Plastics that act as pollutants are cate ...
emits carbon dioxide when it degrades. In 2018 research claimed that some of the most common plastics in the environment release the greenhouse gases methane and
ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon bond, carbon–carbon doub ...
when exposed to sunlight in an amount that can affect the earth climate. Due to the lightness of plastic versus glass or metal, plastic may reduce energy consumption. For example, packaging beverages in PET plastic rather than glass or metal is estimated to save 52% in transportation energy, if the glass or metal package is single-use, of course. In 2019 a new report "Plastic and Climate" was published. According to the report, the production and incineration of plastics will contribute in the equivalent of 850 million tonnes of
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
() to the atmosphere in 2019. With the current trend, annual life cycle greenhouse gas emissions of plastics will grow to 1.34 billion tonnes by 2030. By 2050, the life cycle emissions of plastics could reach 56 billion tonnes, as much as 14 percent of the Earth's remaining carbon budget. The report says that only solutions which involve a reduction in consumption can solve the problem, while others like biodegradable plastic, ocean cleanup, using renewable energy in plastic industry can do little, and in some cases may even worsen it.


Pulp and paper

The global print and paper industry accounts for about 1% of global carbon dioxide emissions. Greenhouse gas emissions from the pulp and paper industry are generated from the combustion of fossil fuels required for raw material production and transportation, wastewater treatment facilities, purchased power, paper transportation, printed product transportation, disposal and recycling.


Various services


Digital services

In 2020,
data center A data center is a building, a dedicated space within a building, or a group of buildings used to house computer systems and associated components, such as telecommunications and storage systems. Since IT operations are crucial for busines ...
s (excluding cryptocurrency mining) and data transmission each used about 1% of world electricity. The digital sector produces between 2% and 4% of global GHG emissions, a large part of which is from chipmaking. However the sector reduces emissions from other sectors which have a larger global share, such as transport of people, and possibly buildings and industry. Mining for
proof-of-work Proof of work (also written as proof-of-work, an abbreviated PoW) is a form of Cryptography, cryptographic proof (truth), proof in which one party (the ''prover'') proves to others (the ''verifiers'') that a certain amount of a specific computatio ...
cryptocurrencies A cryptocurrency (colloquially crypto) is a digital currency designed to work through a computer network that is not reliant on any central authority, such as a government or bank, to uphold or maintain it. Individual coin ownership records ...
requires enormous amounts of electricity and consequently comes with a large
carbon footprint A carbon footprint (or greenhouse gas footprint) is a calculated value or index that makes it possible to compare the total amount of greenhouse gases that an activity, product, company or country Greenhouse gas emissions, adds to the atmospher ...
. Proof-of-work blockchains such as
Bitcoin Bitcoin (abbreviation: BTC; Currency symbol, sign: ₿) is the first Decentralized application, decentralized cryptocurrency. Based on a free-market ideology, bitcoin was invented in 2008 when an unknown entity published a white paper under ...
,
Ethereum Ethereum is a decentralized blockchain with smart contract functionality. Ether (abbreviation: ETH) is the native cryptocurrency of the platform. Among cryptocurrencies, ether is second only to bitcoin in market capitalization. It is open-s ...
,
Litecoin Litecoin (Abbreviation: LTC; sign: Ł) is a decentralized peer-to-peer cryptocurrency and open-source software project released under the MIT/X11 license. Inspired by Bitcoin, Litecoin was the second cryptocurrency starting in October 2011. In te ...
, and Monero were estimated to have added between 3 million and 15 million tonnes of carbon dioxide () to the atmosphere in the period from 1 January 2016 to 30 June 2017. By the end of 2021, Bitcoin was estimated to produce 65.4 million tonnes of , as much as
Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...
, and consume between 91 and 177 terawatt-hours annually. Bitcoin is the least energy-efficient cryptocurrency, using 707.6 kilowatt-hours of electricity per transaction. A study in 2015 investigated the global electricity usage that can be ascribed to
Communication Technology Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...
(CT) between 2010 and 2030. Electricity usage from CT was divided into four principle categories: (i) consumer devices, including personal computers, mobile phones, TVs and home entertainment systems; (ii) network infrastructure; (iii) data center computation and storage; and lastly (iv) production of the above categories. The study estimated for the worst-case scenario, that CT electricity usage could contribute up to 23% of the globally released greenhouse gas emissions in 2030.


Health care

The healthcare sector produces 4.4–4.6% of global greenhouse gas emissions. Based on the 2013 life cycle emissions in the health care sector, it is estimated that the GHG emissions associated with US health care activities may cause an additional 123,000 to 381,000 DALYs annually.


Military

The global carbon footprint of the military sector is around 5.5% of global emissions, which are not included in GHG assessments on global and country level. This estimate do not include the emissions from the conflicts themself, as well as the impact of exhaust gases from aviation in the stratosphere (a factor of 1.9 is applied to emissions from aviation because of this effect) and a possibility of non-exact reporting.


Water supply and sanitation


Tourism

According to UNEP, global tourism is a significant contributor to the increasing concentrations of greenhouse gases in the atmosphere, with air travel accounting for a substantial share of tourism's carbon footprint—up to 70% in some countries like Iceland. Recent studies show that tourism produces around 1 kg of CO₂ per dollar spent—about 25% higher than the global economic average—highlighting its substantial carbon intensity.


Banking

Banks' financed emissions - the greenhouse gas emissions linked to the investment and lending activities of
financial institutions A financial institution, sometimes called a banking institution, is a business entity that provides service as an intermediary for different types of financial monetary transactions. Broadly speaking, there are three major types of financial ins ...
- represent around 75% of their carbon footprint. The Network for Greening the Financial System estimates that climate disasters could dent global economic growth up to 3% in the next five years, and that the financial sector could play a key role in mitigating the risks of climate change. The Net-Zero Banking Alliance has created guidelines for climate target setting for banks, while the Partnership for Carbon Accounting Financials is developing a harmonized approach to assess and disclose the greenhouse gas emissions associated with financial institutions' loans and investments.


Emissions by other characteristics

The responsibility for anthropogenic climate change differs substantially among individuals, e.g. between groups or cohorts.


By type of energy source


By socio-economic class and age

Fueled by the consumptive lifestyle of wealthy people, the wealthiest 5% of the global population has been responsible for 37% of the absolute increase in greenhouse gas emissions worldwide. It can be seen that there is a strong relationship between income and per capita carbon dioxide emissions. Almost half of the increase in absolute global emissions has been caused by the richest 10% of the population. In the newest report from the IPCC 2022, it states that the lifestyle consumptions of the poor and middle class in emerging economies produce approximately 5–50 times less the amount that the high class in already developed high-income countries.Climate Change 2022
ipcc.ch
Variations in regional, and national per capita emissions partly reflect different development stages, but they also vary widely at similar income levels. The 10% of households with the highest per capita emissions contribute a disproportionately large share of global household greenhouse gas emissions. Studies find that the most affluent citizens of the world are responsible for most environmental impacts, and robust action by them is necessary for prospects of moving towards safer environmental conditions. According to a 2020 report by
Oxfam Oxfam is a British-founded confederation of 21 independent non-governmental organizations (NGOs), focusing on the alleviation of global poverty, founded in 1942 and led by Oxfam International. It began as the Oxford Committee for Famine Relief ...
and the Stockholm Environment Institute, the richest 1% of the global population have caused twice as much carbon emissions as the poorest 50% over the 25 years from 1990 to 2015. This was, respectively, during that period, 15% of cumulative emissions compared to 7%. The bottom half of the population is directly responsible for less than 20% of energy footprints and consume less than the top 5% in terms of trade-corrected energy. The largest disproportionality was identified to be in the domain of transport, where e.g. the top 10% consume 56% of vehicle fuel and conduct 70% of vehicle purchases. However, wealthy individuals are also often
shareholder A shareholder (in the United States often referred to as stockholder) of corporate stock refers to an individual or legal entity (such as another corporation, a body politic, a trust or partnership) that is registered by the corporation as the ...
s and typically have more influence and, especially in the case of
billionaire A billionaire is a person with a net worth of at least 1,000,000,000, one billion units of a given currency, usually of a major currency such as the United States dollar, euro, or pound sterling. It is a sub-category of the concept of the ultr ...
s, may also direct lobbying efforts, direct financial decisions, and/or control companies. Based on a study in 32 developed countries, researchers found that "seniors in the United States and Australia have the highest per capita footprint, twice the Western average. The trend is mainly due to changes in expenditure patterns of seniors".


Methods for reducing greenhouse gas emissions

Government A government is the system or group of people governing an organized community, generally a State (polity), state. In the case of its broad associative definition, government normally consists of legislature, executive (government), execu ...
s have taken action to reduce greenhouse gas emissions to
mitigate climate change Climate change mitigation (or decarbonisation) is action to limit the greenhouse gases in the atmosphere that cause climate change. Climate change mitigation actions include energy conservation, conserving energy and Fossil fuel phase-out, repl ...
. Countries and regions listed in Annex I of the
United Nations Framework Convention on Climate Change The United Nations Framework Convention on Climate Change (UNFCCC) is the UN process for negotiating an agreement to limit dangerous climate change. It is an international treaty among countries to combat "dangerous human interference with th ...
(UNFCCC) (i.e., the OECD and former planned economies of the Soviet Union) are required to submit periodic assessments to the UNFCCC of actions they are taking to address climate change. Policies implemented by governments include for example national and regional targets to reduce emissions, promoting energy efficiency, and support for an
energy transition An energy transition (or energy system transformation) is a major structural change to energy supply and consumption in an energy system. Currently, a transition to sustainable energy is underway to limit climate change. Most of the sustainab ...
.


Projections for future emissions

In October 2023, the US
Energy Information Administration The U.S. Energy Information Administration (EIA) is a principal agency of the U.S. Federal Statistical System responsible for collecting, analyzing, and disseminating energy information to promote sound policymaking, efficient markets, and pub ...
(EIA) released a series of projections out to 2050 based on current ascertainable policy interventions. Informally describes as a "narrative" and tagged IEO2023. Landing page. YouTube. Duration: 00:57:12. Includes interview with Joseph DeCarolis. Unlike many integrated systems models in this field, emissions are allowed to float rather than be pinned to netzero in 2050. A
sensitivity analysis Sensitivity analysis is the study of how the uncertainty in the output of a mathematical model or system (numerical or otherwise) can be divided and allocated to different sources of uncertainty in its inputs. This involves estimating sensitivity ...
varied key parameters, primarily future GDP growth (2.6% pa as reference, variously 1.8% and 3.4%) and secondarily technological learning rates, future crude oil prices, and similar exogenous inputs. The model results are far from encouraging. In no case did aggregate energy-related carbon emissions ever dip below 2022 levels (see figure3 plot). The IEO2023 exploration provides a benchmark and suggests that far stronger action is needed.


By country

In 2023, China, the United States, India, EU, Russia, Japan, and Iran - the world's largest emitters - together accounted for 69.7% of total global fossil emissions.


List of countries


United States


China


India


Society and culture


Impacts of the COVID-19 pandemic

In 2020, carbon dioxide emissions fell by 6.4% or 2.3 billion tonnes globally. In April 2020, emissions fell by up to 30%. In China, lockdowns and other measures resulted in a 26% decrease in coal consumption, and a 50% reduction in nitrogen oxide emissions. Greenhouse gas emissions rebounded later in the pandemic as many countries began lifting restrictions, with the direct impact of pandemic policies having a negligible long-term impact on climate change.


See also

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References


External links


Latest official greenhouse gas emissions data of developed countries
from the UNFCCC
Earlier official greenhouse gas emissions data of developed countries
from the UNFCCC
Annual Greenhouse Gas Index (AGGI)
from
NOAA The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with forecasting weather, monitoring oceanic and atmospheric conditions, charting the seas, conducting deep-sea exploratio ...

NOAA CMDL CCGG – Interactive Atmospheric Data Visualization
NOAA data
IPCC Website
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Official IPCC Sixth Assessment Report website
{{DEFAULTSORT:Greenhouse Gas Articles containing video clips Climate forcing Climate change