Greenhouse gas emissions#Industrial processes

{{excerpt|greenhouse effect|paragraphs=1-2|file=no|only=paragraphs}}

File:Global GHG Emissions by gas.png

{{See also|Carbon dioxide in Earth's atmosphere|Atmospheric methane}}

The major anthropogenic (human origin) sources of greenhouse gases are carbon dioxide ({{CO2}}), nitrous oxide ({{chem|N|2|O}}), methane and three groups of fluorinated gases (sulfur hexafluoride ({{chem|SF|6}}), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs, sulphur hexafluoride (SF₆), and nitrogen trifluoride (NF₃)).Dhakal, S., J.C. Minx, F.L. Toth, A. Abdel-Aziz, M.J. Figueroa Meza, K. Hubacek, I.G.C. Jonckheere, Yong-Gun Kim, G.F. Nemet, S. Pachauri, X.C. Tan, T. Wiedmann, 2022: [https://www.ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_Chapter02.pdf Chapter 2: Emissions Trends and Drivers]. In IPCC, 2022: [https://www.ipcc.ch/report/ar6/wg3/ Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [P.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: 10.1017/9781009157926.004 Though the greenhouse effect is heavily driven by water vapor,{{Cite web |date=2023-06-30 |title=Water Vapor |url=https://earthobservatory.nasa.gov/global-maps/MYDAL2_M_SKY_WV |access-date=2023-08-16 |website=earthobservatory.nasa.gov |language=en}} human emissions of water vapor are not a significant contributor to warming.

Although CFCs are greenhouse gases, they are regulated by the Montreal Protocol which was motivated by CFCs' contribution to ozone depletion 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 reached a legally binding accord to phase out hydrofluorocarbons (HFCs) in the Kigali Amendment to the Montreal Protocol.{{Cite web |last1=Johnston |first1=Chris |last2=Milman |first2=Oliver |last3=Vidal |first3=John |date=15 October 2016 |title=Climate change: global deal reached to limit use of hydrofluorocarbons |url=https://www.theguardian.com/environment/2016/oct/15/climate-change-environmentalists-hail-deal-to-limit-use-of-hydrofluorocarbons |access-date=21 August 2018 |website=The Guardian |language=en}}{{cite news |date=15 October 2016 |title=Climate change: 'Monumental' deal to cut HFCs, fastest growing greenhouse gases |work=BBC News |url=https://www.bbc.co.uk/news/science-environment-37665529 |access-date=15 October 2016}}{{cite web |date=15 October 2016 |title=Nations, Fighting Powerful Refrigerant That Warms Planet, Reach Landmark Deal |url=https://www.nytimes.com/2016/10/15/world/africa/kigali-deal-hfc-air-conditioners.html |access-date=15 October 2016 |work=The New York Times}} The use of CFC-12 (except some essential uses) has been phased out due to its ozone depleting properties.{{citation |last1=Vaara |first1=Miska |title=Use of ozone depleting substances in laboratories |url=http://www.norden.org/en/publications/publications/2003-516/ |page=170 |year=2003 |archive-url=https://web.archive.org/web/20110806001547/http://www.norden.org/en/publications/publications/2003-516/ |url-status=dead |publisher=TemaNord |isbn=978-9289308847 |archive-date=6 August 2011}} The phasing-out of less active HCFC-compounds will be completed in 2030.Montreal Protocol

File:Global climate forcing of the industrial era.png

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.{{Cite web |last=Fox |first=Alex |title=Atmospheric Carbon Dioxide Reaches New High Despite Pandemic Emissions Reduction |url=https://www.smithsonianmag.com/smart-news/atmospheric-carbon-dioxide-reaches-new-high-despite-pandemic-emissions-reduction-180977945/ |access-date=22 June 2021 |website=Smithsonian Magazine |language=en}}

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 {{CO2}}-eq in 2023.{{Cite web |title=Executive Summary – CO₂ Emissions in 2023 – Analysis |url=https://www.iea.org/reports/co2-emissions-in-2023/executive-summary |access-date=2024-03-30 |website=IEA |language=en-GB}} The largest single source is coal-fired power stations, with 20% of greenhouse gases (GHG) as of 2021.{{Cite web |title=It's critical to tackle coal emissions – Analysis |url=https://www.iea.org/commentaries/it-s-critical-to-tackle-coal-emissions |access-date=9 October 2021 |website=IEA |date=8 October 2021 |language=en-GB}}
• Land use change (mainly deforestation in the tropics) accounts for about a quarter of total anthropogenic GHG emissions.{{Cite web |last=US EPA |first=OAR |date=12 January 2016 |title=Global Greenhouse Gas Emissions Data |url=https://www.epa.gov/ghgemissions/global-greenhouse-gas-emissions-data |access-date=13 September 2021 |website=www.epa.gov |language=en}}
• Livestock enteric fermentation and manure management,{{Cite report |url=http://www.fao.org/docrep/010/a0701e/a0701e00.htm |title=Livestock's long shadow |last1=Steinfeld |first1=H. |last2=Gerber |first2=P. |publisher=FAO Livestock, Environment and Development (LEAD) Initiative |last3=Wassenaar |first3=T. |last4=Castel |first4=V. |last5=Rosales |first5=M. |last6=de Haan |first6=C. |year=2006}} paddy rice farming, land use and wetland changes, human-made lakes,{{cite book |author1=Ciais, Phillipe |title=Climate Change 2013: The Physical Science Basis |author2=Sabine, Christopher |publisher=IPCC |editor=Stocker Thomas F. |page=473 |chapter=Carbon and Other Biogeochemical Cycles |display-authors=etal |display-editors=etal |chapter-url=http://www.climatechange2013.org/images/report/WG1AR5_ALL_FINAL.pdf}} 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.
• Use of chlorofluorocarbons (CFCs) in refrigeration systems, and use of CFCs and halons in fire suppression systems and manufacturing processes.
• Agricultural soils emit nitrous oxide (N₂O) partly due to application of fertilizers.{{cite journal |last1=Chrobak |first1=Ula |date=14 May 2021 |title=Fighting climate change means taking laughing gas seriously |url=https://knowablemagazine.org/article/food-environment/2021/nitrous-oxide-greenhouse-gas-agriculture |journal=Knowable Magazine |doi=10.1146/knowable-051321-2 |s2cid=236555111 |access-date=8 March 2022|doi-access=free }}
• The largest source of anthropogenic methane emissions is agriculture, closely followed by gas venting and fugitive emissions from the fossil-fuel industry.{{cite web |year=2020 |title=Global Methane Emissions and Mitigation Opportunities |url=https://www.globalmethane.org/documents/gmi-mitigation-factsheet.pdf |website=Global Methane Initiative}}{{cite web |date=20 August 2020 |title=Sources of methane emissions |url=https://www.iea.org/data-and-statistics/charts/sources-of-methane-emissions-2 |website=International Energy Agency}} The largest agricultural methane source is livestock. 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.{{cite web |last= |first= |date=n.d. |title=Key facts and findings |url=https://www.fao.org/news/story/en/item/197623/icode/ |access-date=25 October 2022 |website=Fao.org |publisher=Food and Agricultural Organization |quote= |archive-date=10 October 2023 |archive-url=https://web.archive.org/web/20231010194802/https://www.fao.org/news/story/en/item/197623/icode/ |url-status=dead }}

{{See also|Arctic methane emissions|Greenhouse gas emissions from wetlands}}{{Update section|date=April 2024}}

Global greenhouse gas emissions are about 50 Gt per year{{Cite journal |last1=Ritchie |first1=Hannah |last2=Roser |first2=Max |date=11 May 2020 |title=Greenhouse gas emissions |url=https://ourworldindata.org/greenhouse-gas-emissions |journal=Our World in Data |access-date=22 June 2021}} and for 2019 have been estimated at 57 Gt {{CO2}} eq including 5 Gt due to land use change.{{Cite web |last=PBL |date=21 December 2020 |title=Trends in Global {{CO2}} and Total Greenhouse Gas Emissions; 2020 Report |url=https://www.pbl.nl/en/publications/trends-in-global-co2-and-total-greenhouse-gas-emissions-2020-report |access-date=8 September 2021 |website=PBL Netherlands Environmental Assessment Agency |language=en}} In 2019, approximately 34% [20 Gt{{CO2}}-eq] of total net anthropogenic GHG emissions came from the energy supply sector, 24% [14 Gt{{CO2}}-eq] from industry, 22% [13 Gt{{CO2}}-eq] from agriculture, forestry and other land use (AFOLU), 15% [8.7 Gt{{CO2}}-eq] from transport and 6% [3.3 Gt{{CO2}}-eq] from buildings.{{Cite journal |last=IPCC |date=2019 |title=Summary for Policy Makers |url=https://report.ipcc.ch/ar6wg3/pdf/IPCC_AR6_WGIII_SummaryForPolicymakers.pdf |journal=IPCC |pages=99 |access-date=2022-04-04 |archive-date=2022-08-07 |archive-url=https://web.archive.org/web/20220807023536/https://report.ipcc.ch/ar6wg3/pdf/IPCC_AR6_WGIII_SummaryForPolicymakers.pdf |url-status=dead }}

The current {{CO2}}-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.{{Cite journal |last=Dodman |first=David |date=April 2009 |title=Blaming cities for climate change? An analysis of urban greenhouse gas emissions inventories |journal=Environment and Urbanization |volume=21 |issue=1 |pages=185–201 |doi=10.1177/0956247809103016 |issn=0956-2478 |s2cid=154669383|doi-access=free |bibcode=2009EnUrb..21..185D }}

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.{{Cite web |date=10 July 2017 |title=Just 100 companies responsible for 71% of global emissions, study says |url=http://www.theguardian.com/sustainable-business/2017/jul/10/100-fossil-fuel-companies-investors-responsible-71-global-emissions-cdp-study-climate-change |access-date=9 April 2021 |website=The Guardian |language=en}}{{Cite news |last=Gustin |first=Georgina |date=9 July 2017 |title=25 Fossil Fuel Producers Responsible for Half Global Emissions in Past 3 Decades |url=https://insideclimatenews.org/news/09072017/fossil-fuel-companies-responsible-global-emissions-cdp-report/ |access-date=4 May 2021 |website=Inside Climate News}}

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, 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.{{cite web |date=March 2009 |title=Global Carbon Mechanisms: Emerging lessons and implications (CTC748) |url=http://www.carbontrust.com/resources/reports/advice/global-carbon-mechanisms |access-date=31 March 2010 |publisher=Carbon Trust |page=24}}

2015 was the first year to see both total global economic growth and a reduction of carbon emissions.{{Cite news |last=Vaughan |first=Adam |date=7 December 2015 |title=Global emissions to fall for first time during a period of economic growth |newspaper=The Guardian |url=https://www.theguardian.com/environment/2015/dec/07/global-emissions-to-fall-for-first-time-during-a-period-of-economic-growth |access-date=23 December 2016 |issn=0261-3077}}

File:CO2 emissions vs GDP.svg per capita (2018): In general, countries with a higher GDP per capita also have higher greenhouse gas emissions per capita.{{Cite web |title={{CO2}} emissions per capita vs GDP per capita |url=https://ourworldindata.org/grapher/co2-emissions-vs-gdp |access-date=2023-06-21 |website=Our World in Data}}]]

Annual per capita emissions in the industrialized countries are typically as much as ten times the average in developing countries.{{Rp|144}} 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).{{cite web |date=25 June 2009 |title=Global {{CO2}} emissions: annual increase halves in 2008 |url=http://www.pbl.nl/en/publications/2009/Global-CO2-emissions-annual-increase-halves-in-2008.html |url-status=dead |archive-url=https://web.archive.org/web/20101219064127/http://www.pbl.nl/en/publications/2009/Global-CO2-emissions-annual-increase-halves-in-2008.html |archive-date=19 December 2010 |access-date=5 May 2010 |publisher=Netherlands Environmental Assessment Agency (PBL) website}}

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.

{{Further|Carbon accounting|Carbon footprint|Greenhouse gas inventory}}

File:1800- Global carbon dioxide emissions, per person.svg

There are several ways of measuring greenhouse gas emissions. Some variables that have been reported include:{{cite journal|author=Bader, N.|author2=Bleichwitz, R.|year=2009|title=Measuring urban greenhouse gas emissions: The challenge of comparability |journal=S.A.P.I.EN.S.|volume=2|issue=3|url=http://sapiens.revues.org/index854.html|access-date=11 September 2011}}

• 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 {{CO2}} equivalent. The calculation to determine this takes into account how long that gas remains in the atmosphere. This is not always known accurately{{Clarify|reason=don't we know this well enough by now?|date=June 2021}} 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 systems. These methods differ in accuracy, cost, and usability. Public information from space-based measurements of carbon dioxide by Climate Trace is expected to reveal individual large plants before the 2021 United Nations Climate Change Conference.{{Cite news|title=Transcript: The Path Forward: Al Gore on Climate and the Economy|newspaper=Washington Post|url=https://www.washingtonpost.com/washington-post-live/2021/04/22/transcript-path-forward-al-gore-climate-economy/|access-date=6 May 2021|issn=0190-8286}}

These measures are sometimes used by countries to assert various policy/ethical positions on climate change.{{cite book|author=Banuri, T.|url=https://archive.org/details/climatechange1990000unse_h1m9|title=Equity and social considerations. In: Climate change 1995: Economic and social dimensions of climate change. Contribution of Working Group III to the Second Assessment Report of the Intergovernmental Panel on Climate Change (J.P. Bruce et al. Eds.)|publisher=This version: Printed by Cambridge University Press, Cambridge, and New York. PDF version: IPCC website|year=1996|isbn=978-0521568548|url-access=registration}}{{rp|94}}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.

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.

{{cite book|url=http://www.iea.org/publications/free_new_Desc.asp?PUBS_ID=1927|title=World energy outlook 2007 edition – China and India insights|publisher=International Energy Agency (IEA), Head of Communication and Information Office, 9 rue de la Fédération, 75739 Paris Cedex 15, France|year=2007|isbn=978-9264027305|page=600|access-date=4 May 2010|archive-url=https://web.archive.org/web/20100615062421/http://iea.org/publications/free_new_Desc.asp?PUBS_ID=1927|archive-date=15 June 2010|url-status=dead}}

{{rp|199}}

{{See also|Carbon leakage|}}

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.{{cite journal|last=Holtz-Eakin|first=D.|year=1995|title=Stoking the fires? {{CO2}} emissions and economic growth|url=http://www.nber.org/papers/w4248.pdf|journal=Journal of Public Economics|volume=57|issue=1|pages=85–101|doi=10.1016/0047-2727(94)01449-X|s2cid=152513329}}

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 (UNFCCC) as the base year for emissions, and is also used in the Kyoto Protocol (some gases are also measured from the year 1995).

{{cite journal |author=Grubb, M. |date=July–September 2003 |title=The economics of the Kyoto protocol |url=http://www.econ.cam.ac.uk/rstaff/grubb/publications/J36.pdf |url-status=dead |journal=World Economics |volume=4 |issue=3 |archive-url=https://web.archive.org/web/20110717152152/http://www.econ.cam.ac.uk/rstaff/grubb/publications/J36.pdf |archive-date=17 July 2011}}

{{Rp|146, 149}} 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.

{{cite book|url=https://archive.org/details/developmentclima0000unse|title=World Development Report 2010: Development and Climate Change|publisher=The International Bank for Reconstruction and Development / The World Bank|year=2010|isbn=978-0821379875|location=Washington, DC|at=Tables A1 and A2|chapter=Selected Development Indicators|format=PDF|doi=10.1596/978-0-8213-7987-5|chapter-url=http://siteresources.worldbank.org/INTWDRS/Resources/477365-1327504426766/8389626-1327510418796/Statistical-Annex.pdf}}

{{Rp|370}} Per capita emissions may be based on historical or annual emissions.{{rp|106–107}}

{{See also|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.

{{cite book |author=Helm, D. |url=http://www.dieterhelm.co.uk/sites/default/files/Carbon_record_2007_0.pdf |title=Too Good To Be True? The UK's Climate Change Record |date=10 December 2007 |page=3 |display-authors=etal |archive-url=https://web.archive.org/web/20110715110205/http://www.dieterhelm.co.uk/sites/default/files/Carbon_record_2007_0.pdf |archive-date=15 July 2011 |url-status=dead |df=dmy-all}}

For example, in the main international treaty on climate change (the UNFCCC), countries report on emissions produced within their borders, e.g., the emissions produced from burning fossil fuels.

{{citation |title=World Energy Outlook 2009 |url=http://www.iea.org/textbase/nppdf/free/2009/weo2009.pdf |pages=179–80 |df=dmy-all |year=2009 |access-date=27 December 2011 |archive-url=https://web.archive.org/web/20150924045811/http://www.iea.org/textbase/nppdf/free/2009/weo2009.pdf |url-status=dead |location=Paris |publisher=International Energy Agency (IEA) |isbn=978-9264061309 |archive-date=24 September 2015}}

{{Rp|179}}

{{cite journal |author1=Davis, S.J. |author2=K. Caldeira |date=8 March 2010 |title=Consumption-based Accounting of {{CO2}} Emissions |url=http://www.pnas.org/content/early/2010/02/23/0906974107.full.pdf+html |format=PDF |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=107 |issue=12 |pages=5687–5692 |bibcode=2010PNAS..107.5687D |doi=10.1073/pnas.0906974107 |pmc=2851800 |pmid=20212122 |access-date=18 April 2011 |doi-access=free}}

{{Rp|1}} 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 {{CO2}} 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.{{Rp|4}}

{{Excerpt|Carbon footprint|paragraphs=1-2|file=no}}

{{Further|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.{{cite book |author=Herzog, T. |url=http://pdf.wri.org/target_intensity.pdf |title=Target: intensity – an analysis of greenhouse gas intensity targets |date=November 2006 |publisher=World Resources Institute |isbn=978-1569736388 |editor=Yamashita, M.B. |access-date=11 April 2011}} Emission intensities may be calculated using market exchange rates (MER) or purchasing power parity (PPP).{{Rp|96}}

Carbon accounting (or greenhouse gas accounting) is a framework of methods to measure and track how much greenhouse gas an organization emits.

{{Excerpt|Climate TRACE|paragraphs=1}}

{{multiple image |total_width=500 |header=Cumulative and annual {{CO2}} emissions

| image1=1850- Cumulative emissions of carbon dioxide, by country.svg |caption1= Cumulatively, the U.S. has emitted the greatest amount of {{CO2}}, though China's emission trend is now steeper.

| image2=1850- Annual emissions of carbon dioxide, by country.svg |caption2= Annually, the U.S. emitted the most {{CO2}} until early in the 21st century, when China's annual emissions began to dominate.{{cite journal |last1=Friedlingstein |first1=Pierre |last2=O'Sullivan |first2=Michael |last3=Jones |first3=Matthew W. |last4=Anddrew |first4=Robbie M. |last5=Gregor |first5=Luke |display-authors=4 |title=Global Carbon Budget 2022 (Data description paper) |journal=Earth System Science Data |date=11 November 2022 |volume=14 |issue=11 |pages=4811–4900 |doi=10.5194/essd-14-4811-2022 |url=https://essd.copernicus.org/articles/14/4811/2022/ |doi-access=free |bibcode=2022ESSD...14.4811F |hdl=20.500.11850/594889 |hdl-access=free }} Data available for download at Our World in Data ([https://ourworldindata.org/grapher/cumulative-co-emissions cumulative] and [https://ourworldindata.org/grapher/annual-co2-emissions-per-country annual] and [https://ourworldindata.org/grapher/co-emissions-per-capita?tab=chart per capita]).

}}

{{multiple image |total_width=500

| image1= Cumulative CO2 emission by world region.png |caption1=Cumulative {{CO2}} emission by world region

| image2= Cumulative per person emissions by world region in 3 time periods.png |caption2= Cumulative per person emissions by world region in 3 time periods

}}

File:CO2 Emissions by Source Since 1880.svg

Cumulative anthropogenic (i.e., human-emitted) emissions of {{CO2}} from fossil fuel use are a major cause of global warming,{{cite journal |author=Botzen, W.J.W. |display-authors=etal |year=2008 |title=Cumulative {{CO2}} emissions: shifting international responsibilities for climate debt |journal=Climate Policy |volume=8 |issue=6 |page=570 |doi=10.3763/cpol.2008.0539 |bibcode=2008CliPo...8..569B |s2cid=153972794}} and give some indication of which countries have contributed most to human-induced climate change. In particular, {{CO2}} stays in the atmosphere for at least 150 years and up to 1000 years,{{Cite web |last=Buis |first=Alan |date=Oct 19, 2019 |title=The Atmosphere: Getting a Handle on Carbon Dioxide |url=https://climate.nasa.gov/news/2915/the-atmosphere-getting-a-handle-on-carbon-dioxide |access-date=2023-07-14 |website=Climate Change: Vital Signs of the Planet}} whilst methane disappears within a decade or so,{{Cite web |title=Methane and climate change – Global Methane Tracker 2022 – Analysis |url=https://www.iea.org/reports/global-methane-tracker-2022/methane-and-climate-change |access-date=2023-07-14 |website=IEA |language=en-GB}} and nitrous oxides last about 100 years.{{Cite journal |last1=Prather |first1=Michael J. |last2=Hsu |first2=Juno |last3=DeLuca |first3=Nicole M. |last4=Jackman |first4=Charles H. |last5=Oman |first5=Luke D. |last6=Douglass |first6=Anne R. |last7=Fleming |first7=Eric L. |last8=Strahan |first8=Susan E. |last9=Steenrod |first9=Stephen D. |last10=Søvde |first10=O. Amund |last11=Isaksen |first11=Ivar S. A. |last12=Froidevaux |first12=Lucien |last13=Funke |first13=Bernd |date=2015-06-16 |title=Measuring and modeling the lifetime of nitrous oxide including its variability |journal=Journal of Geophysical Research: Atmospheres |language=en |volume=120 |issue=11 |pages=5693–5705 |doi=10.1002/2015JD023267 |issn=2169-897X |pmc=4744722 |pmid=26900537|bibcode=2015JGRD..120.5693P }} The graph gives some indication of which regions have contributed most to human-induced climate change.{{cite web |title=Climate Watch - Historical Emissions Data |url=https://www.wri.org/data/climate-watch-historical-emissions-data-countries-us-states-unfccc |access-date=23 October 2021 |publisher=World Resources Institute}}

{{cite journal |author=Höhne, N. |display-authors=etal |date=24 September 2010 |title=Contributions of individual countries' emissions to climate change and their uncertainty |url=http://www.gcca.eu/usr/documents/Contributions_Individual_countries_201011229410.pdf |url-status=usurped |journal=Climatic Change |volume=106 |issue=3 |pages=359–91 |doi=10.1007/s10584-010-9930-6 |s2cid=59149563 |archive-url=https://web.archive.org/web/20120426072941/http://www.gcca.eu/usr/documents/Contributions_Individual_countries_201011229410.pdf |archive-date=26 April 2012 |df=dmy-all}}

{{Rp|15}} 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 countries accounted for 42% of cumulative energy-related {{CO2}} emissions between 1890 and 2007.{{Rp|179–80}} 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%.{{Rp|179–80}}The European Commission adopted a set of legislative proposals targeting a reduction of the {{CO2}} emissions by 55% by 2030.

Overall, developed countries accounted for 83.8% of industrial {{CO2}} emissions over this time period, and 67.8% of total {{CO2}} emissions. Developing countries accounted for industrial {{CO2}} emissions of 16.2% over this time period, and 32.2% of total {{CO2}} 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.{{cite web |last=Specktor |first=Brandon |date=1 October 2019 |title=Humans Are Disturbing Earth's Carbon Cycle More Than the Dinosaur-Killing Asteroid Did |url=https://www.livescience.com/anthropogenic-warming-like-dinosaur-killing-asteroid.html |access-date=8 July 2021 |website=livescience.com}}

Transport, together with electricity generation, 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 vehicles and vans. Road travel is the first major source of greenhouse gas emissions from transportation, followed by aircraft and maritime.{{Cite web |title=Transport emissions |url=https://ec.europa.eu/clima/eu-action/transport-emissions_en |access-date=18 October 2021 |website=ec.europa.eu |language=en}}{{Cite web |last=US EPA |first=OAR |date=10 September 2015 |title=Carbon Pollution from Transportation |url=https://www.epa.gov/transportation-air-pollution-and-climate-change/carbon-pollution-transportation |access-date=18 October 2021 |website=www.epa.gov |language=en}} Waterborne transportation is still the least carbon-intensive mode of transportation on average, and it is an essential link in sustainable multimodal freight supply chains.{{Cite web |title=Rail and waterborne — best for low-carbon motorised transport — European Environment Agency |url=https://www.eea.europa.eu/publications/rail-and-waterborne-transport |access-date=18 October 2021 |website=www.eea.europa.eu |language=en}}

Buildings, like industry, are directly responsible for around one-fifth of greenhouse gas emissions, primarily from space heating and hot water consumption. When combined with power consumption within buildings, this figure climbs to more than one-third.{{Cite web |title=Luxembourg 2020 – Analysis |url=https://www.iea.org/reports/luxembourg-2020 |access-date=18 October 2021 |website=IEA |date=25 March 2020 |language=en-GB}}{{Cite web |title=Why The Building Sector? – Architecture 2030 |url=https://architecture2030.org/why-the-building-sector/ |access-date=18 October 2021 |language=en-US}}

Within the EU, the agricultural sector presently accounts for roughly 10% of total greenhouse gas emissions, with methane from livestock accounting for slightly more than half of 10%.{{Cite web |date=6 May 2021 |title=Global Assessment: Urgent steps must be taken to reduce methane emissions this decade |url=https://www.unep.org/news-and-stories/press-release/global-assessment-urgent-steps-must-be-taken-reduce-methane |website=United Nations}}

Estimates of total {{CO2}} emissions do include biotic carbon emissions, mainly from deforestation.{{Rp|94}} Including biotic emissions brings about the same controversy mentioned earlier regarding carbon sinks and land-use change.{{Rp|93–94}} 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.

File:Co2 growth log piecewise.png

The graphic shows the logarithm of 1850–2019 fossil fuel {{CO2}} emissions;{{Cite journal |last1=Friedlingstein |first1=Pierre |last2=O'Sullivan |first2=Michael |last3=Jones |first3=Matthew W. |last4=Andrew |first4=Robbie M. |last5=Hauck |first5=Judith |last6=Olsen |first6=Are |last7=Peters |first7=Glen P. |last8=Peters |first8=Wouter |last9=Pongratz |first9=Julia |last10=Sitch |first10=Stephen |last11=Le Quéré |first11=Corinne |last12=Canadell |first12=Josep G. |last13=Ciais |first13=Philippe |last14=Jackson |first14=Robert B. |last15=Alin |first15=Simone |date=2020 |title=Global Carbon Budget 2020 |url=https://boris.unibe.ch/153200/1/essd-12-3269-2020.pdf |journal=Earth System Science Data |language=en |volume=12 |issue=4 |pages=3269–3340 |bibcode=2020ESSD...12.3269F |doi=10.5194/essd-12-3269-2020 |issn=1866-3516 |doi-access=free|url-access= }} 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. 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.{{Cite web|url=https://www.icos-cp.eu/science-and-impact/global-carbon-budget/2019|title=Global Carbon Budget 2019 | ICOS|website=www.icos-cp.eu}}

{{See also|Greenhouse gas inventory}}

The sharp acceleration in {{CO2}} 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 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, made necessary by the increasing proportion of it that is exported.{{cite journal |author=Raupach, M.R. |last2=Marland |first2=G. |last3=Ciais |first3=P. |last4=Le Quere |first4=C. |last5=Canadell |first5=J. G. |last6=Klepper |first6=G. |last7=Field |first7=C.B. |display-authors=1 |year=2007 |title=Global and regional drivers of accelerating {{CO2}} emissions |url=http://www.pnas.org/cgi/reprint/0700609104v1.pdf |journal=Proc. Natl. Acad. Sci. USA |volume=104 |issue=24 |pages=10288–93 |bibcode=2007PNAS..10410288R |doi=10.1073/pnas.0700609104 |pmc=1876160 |pmid=17519334 |doi-access=free}} In comparison, methane has not increased appreciably, and {{chem|N|2|O}} by 0.25% y⁻¹.

Using different base years for measuring emissions has an effect on estimates of national contributions to global warming.{{Rp|17–18}}The cited paper uses the term "start date" instead of "base year". 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.{{Rp|17–18}}

File:Potential_CO2_emissions_from_large_fossil_fuel_projects_'carbon_bombs'_per_country.jpgThe Global Carbon Project continuously releases data about {{CO2}} emissions, budget and concentration.

{{See also|IPCC list of greenhouse gases}}

{{Pie chart|thumb=right|caption=Distribution of global greenhouse gas emissions based on type of greenhouse gas, without land-use change, using 100 year global warming potential (data from 2020).
Total: 49.8 Gt{{CO2}}eOlivier J.G.J. (2022), [https://www.pbl.nl/sites/default/files/downloads/pbl-2022-trends-in-global-co2-and_total-greenhouse-gas-emissions-2021-summary-report_4758.pdf Trends in global {{CO2}} and total greenhouse gas emissions: 2021 summary report] {{Webarchive|url=https://web.archive.org/web/20230308142245/https://www.pbl.nl/sites/default/files/downloads/pbl-2022-trends-in-global-co2-and_total-greenhouse-gas-emissions-2021-summary-report_4758.pdf |date=2023-03-08 }}. PBL Netherlands, Environmental Assessment Agency, The Hague.{{rp|5}}|label1={{CO2}} mostly by fossil fuel|value1=72|color1=black|label2=CH₄ methane|color2=brown|value2=19|label3={{chem|N|2|O}} nitrous oxide|value3=6|color3=grey|label4=Fluorinated gases|value4=3|color4=blue}}

File:Global_emissions_gas_2015.pngCarbon dioxide ({{CO2}}) is the dominant emitted greenhouse gas, while methane ({{CH4}}) emissions almost have the same short-term impact.{{cite web |date=30 September 2014 |title=Methane vs. Carbon Dioxide: A Greenhouse Gas Showdown |url=http://www.onegreenplanet.org/animalsandnature/methane-vs-carbon-dioxide-a-greenhouse-gas-showdown/ |access-date=13 February 2020 |website=One Green Planet}} Nitrous oxide (N₂O) and fluorinated gases (F-gases) play a lesser role in comparison.

Greenhouse gas emissions are measured in {{CO2}} equivalents determined by their 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, hydrofluorocarbons (HFCs), tropospheric ozone and black carbon persist in the atmosphere for a period ranging from days to 15 years; whereas carbon dioxide can remain in the atmosphere for millennia.{{Cite web |last=IGSD |date=2013 |title=Short-Lived Climate Pollutants (SLCPs) |url=http://www.igsd.org/initiatives/slcps/ |url-status=dead |archive-url=https://web.archive.org/web/20240126094453/https://www.igsd.org/initiatives/slcps/ |archive-date=2024-01-26 |access-date=2024-08-09 |website=Institute of Governance and Sustainable Development (IGSD)}} Reducing SLCP emissions can cut the ongoing rate of global warming by almost half and reduce the projected Arctic warming by two-thirds.{{cite web |last1=Zaelke |first1=Durwood |last2=Borgford-Parnell |first2=Nathan |last3=Andersen |first3=Stephen |last4=Picolotti |first4=Romina |last5=Clare |first5=Dennis |last6=Sun |first6=Xiaopu |last7=Gabrielle |first7=Danielle |year=2013 |title=Primer on Short-Lived Climate Pollutants |url=http://www.igsd.org/documents/PrimeronShort-LivedClimatePollutantsNovemberElectronicversion.pdf |publisher=Institute for Governance and Sustainable Development |pages=3}}

Greenhouse gas emissions in 2019 were estimated at 57.4 Gt{{CO2}}e, while {{CO2}} emissions alone made up 42.5 Gt including land-use change (LUC).using 100 year global warming potential 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. Hence, pairing measures that target carbon dioxide with measures targeting non-{{CO2}} pollutants – short-lived climate pollutants, which have faster effects on the climate, is essential for climate goals.{{cite journal |last1=Dreyfus |first1=Gabrielle B. |last2=Xu |first2=Yangyang |last3=Shindell |first3=Drew T. |last4=Zaelke |first4=Durwood |last5=Ramanathan |first5=Veerabhadran |date=31 May 2022 |title=Mitigating climate disruption in time: A self-consistent approach for avoiding both near-term and long-term global warming |journal=Proceedings of the National Academy of Sciences |language=en |volume=119 |issue=22 |pages=e2123536119 |bibcode=2022PNAS..11923536D |doi=10.1073/pnas.2123536119 |doi-access=free |issn=0027-8424 |pmc=9295773 |pmid=35605122 |s2cid=249014617}}

• Fossil fuel (use for energy generation, transport, heating and machinery in industrial plants): oil, gas and coal (89%) are the major driver of anthropogenic global warming with annual emissions of 35.6 Gt{{CO2}} in 2019.Olivier J.G.J. and Peters J.A.H.W. (2020), [https://www.pbl.nl/sites/default/files/downloads/pbl-2020-trends-in-global-co2-and_total-greenhouse-gas-emissions-2020-report_4331.pdf Trends in global {{CO2}} and total greenhouse gas emissions: 2020 report] {{Webarchive|url=https://web.archive.org/web/20220402191139/https://www.pbl.nl/sites/default/files/downloads/pbl-2020-trends-in-global-co2-and_total-greenhouse-gas-emissions-2020-report_4331.pdf |date=2022-04-02 }}. [https://www.pbl.nl/en PBL Netherlands] {{Webarchive|url=https://web.archive.org/web/20210909141756/https://www.pbl.nl/en/ |date=2021-09-09 }} Environmental Assessment Agency, The Hague.{{rp|20}}
• Cement production (burning of fossil fuels) (4%) is estimated at 1.42 Gt{{CO2}}
• Land-use change (LUC) is the imbalance of deforestation and reforestation. Estimations are very uncertain at 4.5 Gt{{CO2}}. Wildfires alone cause annual emissions of about 7 Gt{{CO2}}{{cite news |last1=Lombrana |first1=Laura Millan |last2=Warren |first2=Hayley |last3=Rathi |first3=Akshat |year=2020 |title=Measuring the Carbon-Dioxide Cost of Last Year's Worldwide Wildfires |publisher=Bloomberg L.P. |url=https://www.bloomberg.com/graphics/2020-fire-emissions/}}{{cite report |url=http://www.globalfiredata.org/_plots/annual_emissions.pdf |title=Global fire annual emissions |publisher=Global Fire Emissions Database |archive-date=2017-10-10 |access-date=2022-11-10 |archive-url=https://web.archive.org/web/20171010185951/http://www.globalfiredata.org/_plots/annual_emissions.pdf |url-status=dead }}
• Non-energy use of fuels, carbon losses in coke ovens, and flaring in crude oil production.

{{See also|Methane emissions|Arctic methane emissions}}

File:Historical_and_future_temperature_projections_showing_importance_of_mitigating_short-lived_climate_pollutants.jpg

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{{rp|6}} has about the same short-term global warming effect as {{CO2}} 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%).{{rp|6}}{{rp|12}}
• Livestock (28%) with cattle (21%) as the dominant source, followed by buffalo (3%), sheep (2%), and goats (1.5%).{{rp|6, 23}}
• 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.{{rp|12}}
• Rice cultivation (10%) on flooded rice fields is another agricultural source, where anaerobic decomposition of organic material produces methane.{{rp|12}}

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 {{CO2}}.{{Cite journal |last=World Meteorological Organization |date=January 2019 |title=Scientific Assessment of ozone Depletion: 2018 |url=https://ozone.unep.org/sites/default/files/2019-05/SAP-2018-Assessment-report.pdf |journal=Global Ozone Research and Monitoring Project |volume=58 |pages=A3 (see Table A1)}} 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.{{rp|12}}Further contributions come from combustion of fossil fuels (18%) and biofuels{{Cite journal |last1=Thompson |first1=R.L |last2=Lassaletta |first2=L. |last3=Patra |first3=P.K |year=2019 |others=et al. |title=Acceleration of global N2O emissions seen from two decades of atmospheric inversion |url=http://pure.iiasa.ac.at/id/eprint/16173/1/N2O_trends_revision2_v1_clean.pdf |journal=Nature Climate Change |volume=9 |issue=12 |pages=993–998 |bibcode=2019NatCC...9..993T |doi=10.1038/s41558-019-0613-7 |s2cid=208302708|url-access= }} as well as industrial production of adipic acid and nitric acid.

Fluorinated gases include hydrofluorocarbons (HFC), perfluorocarbons (PFC), sulfur hexafluoride (SF₆), and nitrogen trifluoride (NF₃). They are used by switchgear in the power sector, semiconductor manufacture, aluminum production and a largely unknown source of SF₆.{{rp|38}} Continued phase down of manufacture and use of HFCs under the Kigali Amendment 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 leakages contribute to indirect global warming.{{cite web|url=https://www.rechargenews.com/energy-transition/hydrogen-twice-as-powerful-a-greenhouse-gas-as-previously-thought-uk-government-study/2-1-1200115 |title=Hydrogen 'twice as powerful a greenhouse gas as previously thought': UK government study |date=8 April 2022 |access-date=3 March 2023 }}

When hydrogen is oxidized in the atmosphere, the result is an increase in concentrations of greenhouse gases in both the troposphere and the stratosphere.{{cite journal |last1=Ocko |first1=Illisa |last2=Hamburg |first2=Steven |date=20 July 2022 |title=Climate consequences of hydrogen emissions |url=https://acp.copernicus.org/preprints/acp-2022-91/acp-2022-91.pdf |journal=Atmospheric Chemistry and Physics |volume=22 |issue=14 |pages=9349–9368 |doi=10.5194/acp-22-9349-2022 |bibcode=2022ACP....22.9349O |s2cid=250930654 |access-date=25 April 2023 |doi-access=free |url-access= }} Hydrogen can leak from hydrogen production facilities as well as any infrastructure in which hydrogen is transported, stored, or consumed.{{Cite journal |last1=Cooper |first1=Jasmin |last2=Dubey |first2=Luke |last3=Bakkaloglu |first3=Semra |last4=Hawkes |first4=Adam |date=2022-07-15 |title=Hydrogen emissions from the hydrogen value chain-emissions profile and impact to global warming |journal=Science of the Total Environment |volume=830 |pages=154624 |doi=10.1016/j.scitotenv.2022.154624 |pmid=35307429 |bibcode=2022ScTEn.83054624C |s2cid=247535630 |issn=0048-9697|doi-access=free |hdl=10044/1/96970 |hdl-access=free }}

Black carbon is formed through the incomplete combustion of fossil fuels, biofuel, and biomass. It is not a greenhouse gas but a climate forcing agent. Black carbon can absorb sunlight and reduce albedo when deposited on snow and ice. Indirect heating can be caused by the interaction with clouds.{{Cite journal |last=Bond |display-authors=etal |date=2013 |title=Bounding the role of black carbon in the climate system: A scientific assessment |journal=J. Geophys. Res. Atmos. |volume=118 |issue=11 |pages=5380–5552 |bibcode=2013JGRD..118.5380B |doi=10.1002/jgrd.50171 |doi-access=free|hdl=2027.42/99106 |hdl-access=free }} Black carbon stays in the atmosphere for only several days to weeks.{{cite journal |last1=Ramanathan |first1=V. |last2=Carmichael |first2=G. |date=April 2008 |title=Global and regional climate changes due to black carbon |journal=Nature Geoscience |volume=1 |issue=4 |pages=221–227 |bibcode=2008NatGe...1..221R |doi=10.1038/ngeo156}} Emissions may be mitigated by upgrading coke ovens, installing particulate filters on diesel-based engines, reducing routine flaring, and minimizing open burning of biomass.

{{See also|Climate change mitigation#Mitigation by sector}}

File:Greenhouse Gas Emissions by Economic Sector.svg

File:Global GHG Emissions by Sector 2016.png

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.

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.{{Cite web |title=Life Cycle Assessment of Electricity Generation Options {{!}} UNECE |url=https://unece.org/sed/documents/2021/10/reports/life-cycle-assessment-electricity-generation-options |access-date=2021-11-26 |website=unece.org}}

Energy may be produced at the point of consumption, 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.IEA, {{CO2}} Emissions from Fuel Combustion 2018: Highlights (Paris: International Energy Agency, 2018) p.98 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.IEA, {{CO2}} Emissions from Fuel Combustion 2018: Highlights (Paris: International Energy Agency, 2018) p.101 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.

{{See also|Life-cycle greenhouse gas emissions of energy sources}}

File:Guevara_2024_power_plant_emissions.png

Coal-fired power stations are the single largest emitter, with over 20% of global greenhouse gas emissions in 2018.{{Cite web |title=Emissions |url=https://www.iea.org/geco/emissions/ |url-status=dead |archive-url=https://web.archive.org/web/20190812215445/https://www.iea.org/geco/emissions/ |archive-date=12 August 2019 |access-date=21 September 2019 |website=www.iea.org}} Although much less polluting than coal plants, natural gas-fired power plants are also major emitters,{{Cite web |date=1 July 2019 |title=We have too many fossil-fuel power plants to meet climate goals |url=https://www.nationalgeographic.com/environment/2019/07/we-have-too-many-fossil-fuel-power-plants-to-meet-climate-goals/ |archive-url=https://web.archive.org/web/20190702105444/https://www.nationalgeographic.com/environment/2019/07/we-have-too-many-fossil-fuel-power-plants-to-meet-climate-goals/ |url-status=dead |archive-date=July 2, 2019 |access-date=21 September 2019 |website=Environment |language=en}} taking electricity generation as a whole over 25% in 2018.{{Cite web |title=March: Tracking the decoupling of electricity demand and associated {{CO2}} emissions |url=https://www.iea.org/newsroom/news/2019/march/tracking-the-decoupling-of-electricity-demand-and-associated-co2-emissions.html |access-date=21 September 2019 |website=www.iea.org}} 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.{{Cite journal |last1=Grant |first1=Don |last2=Zelinka |first2=David |last3=Mitova |first3=Stefania |date=13 July 2021 |title=Reducing {{CO2}} emissions by targeting the world's hyper-polluting power plants |journal=Environmental Research Letters |volume=16 |issue=9 |page=094022 |bibcode=2021ERL....16i4022G |doi=10.1088/1748-9326/ac13f1 |issn=1748-9326 |doi-access=free|url=https://scholar.colorado.edu/downloads/9z903115h }} 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.Emission Trends and Drivers, Chap. 2 in "Climate Change 2022: Mitigation of Climate Change" https://www.ipcc.ch/report/ar6/wg3/ {{Webarchive|url=https://web.archive.org/web/20220802125242/https://www.ipcc.ch/report/ar6/wg3/ |date=2022-08-02 }}

In March 2024, the International Energy Agency (IEA) reported that in 2023, global {{CO2}} 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.{{Cite web |date=March 2024 |title=CO₂ Emissions in 2023 – Analysis |url=https://www.iea.org/reports/co2-emissions-in-2023 |access-date=2024-03-22 |website=IEA |language=en-GB}} The implementation of clean energy technologies like solar, wind, nuclear, heat pumps, and electric vehicles since 2019 has significantly tempered emissions growth, which would have been threefold without these technologies.

{{See also|Methane emissions}}

{{excerpt|Greenhouse gas emissions from agriculture|paragraphs=1-3|file=no}}

File:Spatial pattern of forest carbon loss across the tropics.webp

{{Further|Deforestation#Atmospheric|Deforestation and climate change}}

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){{cite news |date=28 February 2022 |title=Deforestation emissions far higher than previously thought, study finds |language=en |work=The Guardian |url=https://www.theguardian.com/environment/2022/feb/28/deforestation-emissions-far-higher-than-previously-thought-study-finds-aoe |access-date=16 March 2022}}

{{Main|Greenhouse gas emissions from agriculture}}

File:2019 Greenhouse gas emissions per capita by region - variwide bar chart - IPCC AR6 WG3 - Fig SPM.2c.svg

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 sinks.{{citation |title=Annex I: Glossary J–P |url=http://www.ipcc.ch/publications_and_data/ar4/wg3/en/annex1sglossary-j-p.html |editor1=B. Metz |archive-url=https://web.archive.org/web/20100503041746/http://www.ipcc.ch/publications_and_data/ar4/wg3/en/annex1sglossary-j-p.html |archive-date=3 May 2010 |editor2=O.R. Davidson |editor3=P.R. Bosch |editor4=R. Dave |editor5=L.A. Meyer |url-status=dead}} 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.{{Rp|92–93}}

There are substantial uncertainties in the measurement of net carbon emissions.{{cite book |author=Markandya, A. |title=Costing Methodologies |publisher=Print version: Cambridge University Press, Cambridge, and New York. This version: GRID-Arendal website |year=2001 |isbn=978-0521015028 |editor=B. Metz |series=Climate Change 2001: Mitigation. Contribution of Working Group III to the Third Assessment Report of the Intergovernmental Panel on Climate Change |chapter=7.3.5 Cost Implications of Alternative GHG Emission Reduction Options and Carbon Sinks |access-date=11 April 2011 |display-editors=etal |chapter-url=http://www.grida.no/climate/ipcc_tar/wg3/293.htm |archive-url=https://web.archive.org/web/20110805022315/http://www.grida.no/climate/ipcc_tar/wg3/293.htm |archive-date=5 August 2011 |url-status=dead |df=dmy-all}} Additionally, there is controversy over how carbon sinks should be allocated between different regions and over time.{{Rp|93}} 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.{{Cite journal |last1=Page |first1=S. |last2=Siegert |first2=F. |last3=Rieley |first3=J. |last4=Boehm |first4=H. |last5=Jaya |first5=A. |last6=Limin |first6=S. |year=2002 |title=The amount of carbon released from peat and forest fires in Indonesia during 1997 |journal=Nature |volume=420 |issue=6911 |pages=61–65 |bibcode=2002Natur.420...61P |doi=10.1038/nature01131 |pmid=12422213 |s2cid=4379529}}{{cite web |last=Lazaroff |first=Cat |date=2002-11-08 |title=Indonesian Wildfires Accelerated Global Warming |url=http://www.ens-newswire.com/ens/nov2002/2002-11-08-06.asp |url-status=dead |archive-url=https://web.archive.org/web/20190908133919/http://www.ens-newswire.com/ens/nov2002/2002-11-08-06.asp |archive-date=8 September 2019 |access-date=2011-11-07 |work=Environment New Service}}{{cite news |author=Pearce, Fred |date=6 November 2004 |title=Massive peat burn is speeding climate change |publisher=New Scientist |url=https://www.newscientist.com/article.ns?id=dn6613}}

File:World_fossil_carbon_dioxide_emissions_six_top_countries_and_confederations.png{{Further|Climate change mitigation#Transport|Environmental effects of shipping#Greenhouse gas emissions|Environmental aspects of the electric car|Environmental design in rail transportation}}Transportation accounts for 15% of emissions worldwide.{{Cite journal |last1=Ge |first1=Mengpin |last2=Friedrich |first2=Johannes |last3=Vigna |first3=Leandro |date=6 February 2020 |title=4 Charts Explain Greenhouse Gas Emissions by Countries and Sectors |url=https://www.wri.org/blog/2020/02/greenhouse-gas-emissions-by-country-sector |language=en |access-date=30 December 2020 |website=World Resources Institute}} Over a quarter of global transport {{CO2}} emissions are from road freight,{{Cite web |title=Cars, planes, trains: where do {{CO2}} emissions from transport come from? |url=https://ourworldindata.org/co2-emissions-from-transport |access-date=19 June 2021 |website=Our World in Data}} so many countries are further restricting truck {{CO2}} emissions to help limit climate change.{{cite news |date=20 December 2018 |title=EU countries agree to 30 percent cut in truck {{CO2}} emissions |work=Reuters |url=https://www.reuters.com/article/us-eu-autos-emissions/eu-countries-agree-to-30-percent-cut-in-truck-co2-emissions-idUSKCN1OJ1ZC}}

Maritime transport accounts for 3.5% to 4% of all greenhouse gas emissions, primarily carbon dioxide.{{Cite book |last1=Walker |first1=Tony R. |title=World Seas: An Environmental Evaluation |last2=Adebambo |first2=Olubukola |last3=Del Aguila Feijoo |first3=Monica C. |last4=Elhaimer |first4=Elias |last5=Hossain |first5=Tahazzud |last6=Edwards |first6=Stuart Johnston |last7=Morrison |first7=Courtney E. |last8=Romo |first8=Jessica |last9=Sharma |first9=Nameeta |year=2019 |isbn=978-0-12-805052-1 |pages=505–530 |chapter=Environmental Effects of Marine Transportation |doi=10.1016/B978-0-12-805052-1.00030-9 |name-list-style=vanc |last10=Taylor |first10=Stephanie |last11=Zomorodi |first11=Sanam |s2cid=135422637}}{{Cite news |last=Vidal |first=John |date=2009-04-09 |title=Health risks of shipping pollution have been 'underestimated' |work=The Guardian |url=https://www.theguardian.com/environment/2009/apr/09/shipping-pollution |access-date=2009-07-03}} 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."{{Cite web |date=2022-03-16 |title=Infrastructure Podcast; Decarbonized Shipping |url=https://www.worldbank.org/en/news/podcast/2022/03/16/decarbonized-shipping-reducing-the-dependence-on-fossil-fuels |access-date=2022-08-18 |publisher=World Bank}}{{Cite web |last1=Kersing |first1=Arjen |last2=Stone |first2=Matt |date=2022-01-25 |title=Charting global shipping's path to zero carbon |url=https://www.mckinsey.com/industries/travel-logistics-and-infrastructure/our-insights/charting-global-shippings-path-to-zero-carbon |access-date=2022-08-18 |publisher=McKinsey}}{{Cite web |last=Raucci |first=Carlo |date=2019-06-06 |title=Three pathways to shipping's decarbonization |url=https://www.globalmaritimeforum.org/news/three-pathways-to-shippings-decarbonization |access-date=2022-08-18 |publisher=Global Maritime Forum |archive-date=2023-05-28 |archive-url=https://web.archive.org/web/20230528042844/https://www.globalmaritimeforum.org/news/three-pathways-to-shippings-decarbonization |url-status=dead }}

{{Further|Environmental effects of aviation#Climate change}}

Jet airliners contribute to climate change by emitting carbon dioxide ({{CO2}}), nitrogen oxides, contrails and particulates.In 2018, global commercial operations generated 2.4% of all {{CO2}} emissions.{{cite web |author=Brandon Graver |author2=Kevin Zhang |author3=Dan Rutherford |date=September 2019 |title={{CO2}} emissions from commercial aviation, 2018 |url=https://theicct.org/sites/default/files/publications/ICCT_CO2-commercl-aviation-2018_20190918.pdf |publisher=International Council on Clean Transportation}}

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.{{cite news |last1=Davidson |first1=Jordan |date=4 September 2020 |title=Aviation Accounts for 3.5% of Global Warming Caused by Humans, New Research Says |agency=Ecowatch |url=https://www.ecowatch.com/aviation-emissions-global-warming-2647461303.html |access-date=6 September 2020}}

Some representative figures for {{CO2}} average direct emissions (not accounting for high-altitude radiative effects) of airliners expressed as {{CO2}} and {{CO2}} equivalent per passenger kilometer:{{cite web |title=Average passenger aircraft emissions and energy consumption per passenger kilometre in Finland 2008 |url=http://lipasto.vtt.fi/yksikkopaastot/henkiloliikennee/ilmaliikennee/ilmae.htm |url-status=live |archive-url=https://web.archive.org/web/20110719224215/http://lipasto.vtt.fi/yksikkopaastot/henkiloliikennee/ilmaliikennee/ilmae.htm |archive-date=19 July 2011 |access-date=3 July 2009 |website=lipasto.vtt.fi}}

• Domestic, short distance, less than {{convert|463|km|mi|0|abbr=on}}: 257 g/km {{CO2}} or 259 g/km (14.7 oz/mile) {{CO2}}e
• Long-distance flights: 113 g/km {{CO2}} or 114 g/km (6.5 oz/mile) {{CO2}}e

{{Pie chart|thumb=right|caption={{CO2}} emissions by fuel type (as of 2023)|label1=coal|value1=41|color1=#602200|label2=oil|value2=32|color2=#333333|label3=gas|value3=21|color3=#888800|label4=cement|value4=4|color4=#888888|label5=others|value5=2|color5=#000050}}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.{{cite journal |last1=Ürge-Vorsatz |first1=Diana |last2=Khosla |first2=Radhika |last3=Bernhardt |first3=Rob |last4=Chan |first4=Yi Chieh |last5=Vérez |first5=David |last6=Hu |first6=Shan |last7=Cabeza |first7=Luisa F. |year=2020 |title=Advances Toward a Net-Zero Global Building Sector |journal=Annual Review of Environment and Resources |volume=45 |pages=227–269 |doi=10.1146/annurev-environ-012420-045843 |doi-access=free|hdl=10459.1/69710 |hdl-access=free }} Because building construction is a significant investment, more than two-thirds of buildings in existence will still exist in 2050. Retrofitting 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.{{cite web |title=Why the building sector? |url=https://architecture2030.org/buildings_problem_why/ |access-date=1 April 2021 |website=Architecture 2020}} Buildings that produce as much energy as they consume are called zero-energy buildings, 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.

The construction industry has seen marked advances in building performance and energy efficiency over recent decades.{{Cite journal |last1=Fowlie |first1=Meredith |last2=Greenstone |first2=Michael |last3=Wolfram |first3=Catherine |date=2018-08-01 |title=Do Energy Efficiency Investments Deliver? Evidence from the Weatherization Assistance Program |url=https://academic.oup.com/qje/article/133/3/1597/4828342 |url-status=live |journal=The Quarterly Journal of Economics |language=en |volume=133 |issue=3 |pages=1597–1644 |doi=10.1093/qje/qjy005 |issn=0033-5533 |archive-url=https://web.archive.org/web/20200607184218/https://academic.oup.com/qje/article/133/3/1597/4828342 |archive-date=2020-06-07 |access-date=2020-11-21}} 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.{{Cite web |date=23 June 2017 |title=Sequestering Carbon in Buildings |url=http://www.greenenergytimes.org/2017/06/23/sequestering-carbon-in-buildings/ |access-date=22 January 2021 |website=Green Energy Times |language=en-US}}

In 2019, the building sector was responsible for 12 Gt{{CO2}}-eq emissions. More than 95% of these emissions were carbon, and the remaining 5% were {{CH4}}, {{chem2|N2O}}, and halocarbon.{{Cite web |title=IPCC — Intergovernmental Panel on Climate Change |url=https://www.ipcc.ch/ |access-date=4 April 2022}}

The largest contributor to building sector emissions (49% of total) is the production of electricity for use in buildings.{{Cite book |last=International Energy Agency |url=https://www.iea.org/reports/global-status-report-for-buildings-and-construction-2019 |title=Global Status Report for Buildings and Construction 2019 |publisher=IEA |year=2019 |isbn=978-92-807-3768-4 |location=Paris |author-link=International Energy Agency |access-date=2020-11-20 |archive-url=https://web.archive.org/web/20201126024632/https://www.iea.org/reports/global-status-report-for-buildings-and-construction-2019 |archive-date=2020-11-26 |url-status=live}}

Of global building sector GHG emissions, 28% are produced during the manufacturing process of building materials such as steel, cement (a key component of concrete),{{Cite web |title=CoatingsTech - Coatings and Low-carbon Cement Technology |url=https://www.coatingstech-digital.org/coatingstech/library/item/july_2022/4025830/ |access-date=2022-07-07 |website=www.coatingstech-digital.org |language=en}} 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.{{Cite journal |last1=De Ras |first1=Kevin |last2=Van De Vijver |first2=Ruben |last3=Galvita |first3=Vladimir V. |last4=Marin |first4=Guy B. |last5=Van Geem |first5=Kevin M. |date=2019-12-01 |title=Carbon capture and utilization in the steel industry: challenges and opportunities for chemical engineering |url=https://www.sciencedirect.com/science/article/abs/pii/S221133981930036X |url-status=live |journal=Current Opinion in Chemical Engineering |language=en |volume=26 |pages=81–87 |doi=10.1016/j.coche.2019.09.001 |bibcode=2019COCE...26...81D |issn=2211-3398 |s2cid=210619173 |archive-url=https://web.archive.org/web/20210520201639/https://www.sciencedirect.com/science/article/abs/pii/S221133981930036X |archive-date=2021-05-20 |access-date=2021-07-02 |hdl=1854/LU-8635595|hdl-access=free }}

The remaining 23% of global building sector GHG emissions are produced directly on site during building operations.

Embodied carbon emissions, or upfront carbon emissions (UCE), are the result of creating and maintaining the materials that form a building.{{Cite web |last=Alter |first=Lloyd |date=1 April 2019 |title=Let's rename "Embodied Carbon" to "Upfront Carbon Emissions" |url=https://www.treehugger.com/green-architecture/lets-rename-embodied-carbon-upfront-carbon-emissions.html |url-status=live |archive-url=https://web.archive.org/web/20190401151555/https://www.treehugger.com/green-architecture/lets-rename-embodied-carbon-upfront-carbon-emissions.html |archive-date=1 April 2019 |access-date=10 August 2019 |website=TreeHugger |language=en}} 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."{{Cite web |title=New Buildings: Embodied Carbon |url=https://architecture2030.org/new-buildings-embodied/ |url-status=live |archive-url=https://web.archive.org/web/20181212173439/https://architecture2030.org/new-buildings-embodied/ |archive-date=12 December 2018 |access-date=10 August 2019 |website=Architecture 2030 |language=en-US}}

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.{{Cite journal |last1=Pomponi |first1=Francesco |last2=Moncaster |first2=Alice |date=2016 |title=Embodied carbon mitigation and reduction in the built environment - What does the evidence say? |url=https://www.repository.cam.ac.uk/handle/1810/260832 |url-status=live |journal=Journal of Environmental Management |volume=181 |pages=687–700 |doi=10.1016/j.jenvman.2016.08.036 |pmid=27558830 |bibcode=2016JEnvM.181..687P |archive-url=https://web.archive.org/web/20211120193019/https://www.repository.cam.ac.uk/handle/1810/260832 |archive-date=2021-11-20 |access-date=2021-07-27}} 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.

{{See also|Environmental impact of concrete#Carbon dioxide emissions and climate change}}

{{As of|2020|}} Secunda CTL is the world's largest single emitter, at 56.5 million tonnes {{CO2}} a year.{{Cite news |date=17 March 2020 |title=The World's Biggest Emitter of Greenhouse Gases |language=en |work=Bloomberg.com |url=https://www.bloomberg.com/news/features/2020-03-17/south-africa-living-near-the-world-s-biggest-emitting-plant |access-date=29 December 2020}}

Flaring and venting of natural gas 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.[http://cdiac.esd.ornl.gov/trends/emis/tre_glob.htm Global, Regional, and National CO₂ Emissions] {{webarchive|url=https://web.archive.org/web/20070711043835/http://cdiac.esd.ornl.gov/trends/emis/tre_glob.htm|date=2007-07-11}}. In Trends: A Compendium of Data on Global Change, Marland, G., T.A. Boden, and R. J. Andres, 2005, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee.

The World Bank 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 and France 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%.{{cite web |author= |title=Global Gas Flaring Reduction Partnership (GGFR) |url=http://www.worldbank.org/en/programs/gasflaringreduction |url-status=live |archive-url=https://web.archive.org/web/20160826152139/http://www.worldbank.org/en/programs/gasflaringreduction |archive-date=August 26, 2016 |access-date=August 24, 2016 |website=worldbank.org |publisher=The World Bank |quote=previous redirect from web.worldbank.org}}

Steel and aluminum are key economic sectors where {{CO2}} is produced. According to a 2013 study, "in 2004, the steel industry along emits about 590M tons of {{CO2}}, which accounts for 5.2% of the global anthropogenic GHG emissions. {{CO2}} emitted from steel production primarily comes from energy consumption of fossil fuel as well as the use of limestone to purify iron oxides."{{cite journal |last1=Tsaia |first1=I-Tsung |last2=Al Alia |first2=Meshayel |last3=El Waddi |first3=Sanaâ |last4=Adnan Zarzourb |first4=aOthman |year=2013 |title=Carbon Capture Regulation for the Steel and Aluminum Industries in the UAE: An Empirical Analysis |journal=Energy Procedia |volume=37 |issue= |pages=7732–7740 |doi=10.1016/j.egypro.2013.06.719 |issn=1876-6102 |oclc=5570078737 |doi-access=free|bibcode=2013EnPro..37.7732T }}

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.{{Cite journal |last1=Zheng |first1=Jiajia |last2=Suh |first2=Sangwon |date=May 2019 |title=Strategies to reduce the global carbon footprint of plastics |url=https://escholarship.org/content/qt8pp2t7v8/qt8pp2t7v8.pdf?t=qxd7cq |journal=Nature Climate Change |language=en |volume=9 |issue=5 |pages=374–378 |bibcode=2019NatCC...9..374Z |doi=10.1038/s41558-019-0459-z |issn=1758-6798 |s2cid=145873387|url-access= }} The EPA estimates{{cite web |last= |first= |date=2009 |title=The Link Between Plastic Use and Climate Change: Nitty-gritty |url=https://stanfordmag.org/contents/the-link-between-plastic-use-and-climate-change-nitty-gritty |access-date=5 March 2021 |website=stanfordmag.org |publisher= |quote=... According to the EPA, approximately one ounce of carbon dioxide is emitted for each ounce of polyethylene (PET) produced. PET is the type of plastic most commonly used for beverage bottles. ...'}} as many as five mass units of carbon dioxide are emitted for each mass unit of polyethylene terephthalate (PET) produced—the type of plastic most commonly used for beverage bottles,{{cite web |last1=Glazner |first1=Elizabeth |title=Plastic Pollution and Climate Change |url=http://www.plasticpollutioncoalition.org/pft/2015/11/17/plastic-pollution-and-climate-change |access-date=6 August 2018 |website=Plastic Pollution Coalition |date=21 November 2017 }} the transportation produce greenhouse gases also.{{cite web |last1=Blue |first1=Marie-Luise |title=What Is the Carbon Footprint of a Plastic Bottle? |url=https://sciencing.com/carbon-footprint-plastic-bottle-12307187.html |access-date=6 August 2018 |website=Sciencing |date=11 June 2018 |publisher=Leaf Group Ltd}} Plastic waste 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 when exposed to sunlight in an amount that can affect the earth climate.{{cite journal |last1=Royer |first1=Sarah-Jeanne |last2=Ferrón |first2=Sara |last3=Wilson |first3=Samuel T. |last4=Karl |first4=David M. |date=1 August 2018 |title=Production of methane and ethylene from plastics in the environment |journal=PLOS ONE |volume=13 |issue=Plastic, Climate Change |pages=e0200574 |bibcode=2018PLoSO..1300574R |doi=10.1371/journal.pone.0200574 |pmc=6070199 |pmid=30067755 |doi-access=free}}{{cite news |last1=Rosane |first1=Olivia |date=2 August 2018 |title=Study Finds New Reason to Ban Plastic: It Emits Methane in the Sun |agency=Ecowatch |issue=Plastic, Climate Change |url=https://www.ecowatch.com/plastic-waste-could-contribute-to-climate-change-2592101036.html |access-date=6 August 2018}}

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 ({{CO2}}) 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.{{cite web |title=Sweeping New Report on Global Environmental Impact of Plastics Reveals Severe Damage to Climate |url=https://www.ciel.org/news/plasticandclimate/ |access-date=16 May 2019 |website=Center for International Environmental Law (CIEL)}} 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.{{cite book |url=https://www.ciel.org/wp-content/uploads/2019/05/Plastic-and-Climate-FINAL-2019.pdf |title=Plastic & Climate The Hidden Costs of a Plastic Planet |date=May 2019 |publisher=Center for International Environmental Law, Environmental Integrity Project, FracTracker Alliance, Global Alliance for Incinerator Alternatives, 5 Gyres, and Break Free From Plastic. |pages=82–85 |access-date=20 May 2019}}

{{Further|Environmental effects of paper#Greenhouse gas emissions}}

The global print and paper industry accounts for about 1% of global carbon dioxide emissions.{{cite web |date=2010 |title=World GHG Emissions Flow Chart |url=http://www.ecofys.com/files/files/asn-ecofys-2013-world-ghg-emissions-flow-chart-2010.pdf |access-date=16 August 2018 |website=Ecofys.com |archive-date=6 November 2018 |archive-url=https://web.archive.org/web/20181106225025/https://www.ecofys.com/files/files/asn-ecofys-2013-world-ghg-emissions-flow-chart-2010.pdf |url-status=dead }} 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.

{{See also|Streaming media#Greenhouse gas emissions|Data center#Greenhouse gas emissions|Cryptocurrency#Environmental effects}}

In 2020, data centers (excluding cryptocurrency mining) and data transmission each used about 1% of world electricity.{{Cite web |title=Data Centres and Data Transmission Networks – Analysis |url=https://www.iea.org/reports/data-centres-and-data-transmission-networks |access-date=2022-03-06 |website=IEA |language=en-GB}} The digital sector produces between 2% and 4% of global GHG emissions,{{Cite arXiv |eprint=2102.02622 |class=physics.soc-ph |first1=Charlotte |last1=Freitag |first2=Mike |last2=Berners-Lee |title=The climate impact of ICT: A review of estimates, trends and regulations |date=December 2020}} a large part of which is from chipmaking.{{Cite web |date=18 September 2021 |title=The computer chip industry has a dirty climate secret |url=https://www.theguardian.com/environment/2021/sep/18/semiconductor-silicon-chips-carbon-footprint-climate |access-date=18 September 2021 |website=the Guardian |language=en}} However the sector reduces emissions from other sectors which have a larger global share, such as transport of people,{{Cite web |date=19 May 2020 |title=Working from home is erasing carbon emissions -- but for how long? |url=https://grist.org/climate/working-from-home-is-erasing-carbon-emissions-but-for-how-long/ |access-date=4 April 2021 |website=Grist |language=en-us}} and possibly buildings and industry.{{Cite web |last=Cunliff |first=Colin |date=6 July 2020 |title=Beyond the Energy Techlash: The Real Climate Impacts of Information Technology |url=https://itif.org/publications/2020/07/06/beyond-energy-techlash-real-climate-impacts-information-technology |language=en}}

Mining for proof-of-work cryptocurrencies requires enormous amounts of electricity and consequently comes with a large carbon footprint.{{Cite journal |last=Foteinis |first=Spyros |date=7 February 2018 |title=Bitcoin's alarming carbon footprint |journal=Nature |language=en |volume=554 |issue=7691 |page=169 |bibcode=2018Natur.554..169F |doi=10.1038/d41586-018-01625-x |doi-access=free}} Proof-of-work blockchains such as Bitcoin, Ethereum, Litecoin, and Monero were estimated to have added between 3 million and 15 million tonnes of carbon dioxide ({{CO2}}) to the atmosphere in the period from 1 January 2016 to 30 June 2017.{{cite journal |last1=Krause |first1=Max J. |last2=Tolaymat |first2=Thabet |date=November 2018 |title=Quantification of energy and carbon costs for mining cryptocurrencies |journal=Nature Sustainability |volume=1 |issue=11 |pages=711–718 |doi=10.1038/s41893-018-0152-7 |bibcode=2018NatSu...1..711K |s2cid=169170289}} By the end of 2021, Bitcoin was estimated to produce 65.4 million tonnes of {{CO2}}, as much as Greece,{{cite web |last=Davies |first=Pascale |date=26 February 2022 |title=Bitcoin mining is worse for the environment now since China banned it |url=https://www.euronews.com/next/2022/02/26/bitcoin-mining-was-actually-worse-for-the-environment-since-china-banned-it-a-new-study-sa |access-date=1 March 2022 |website=euronews |language=en}} 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.{{cite web |last=Ponciano |first=Jonathan |title=Bill Gates Sounds Alarm On Bitcoin's Energy Consumption–Here's Why Crypto Is Bad For Climate Change |url=https://www.forbes.com/sites/jonathanponciano/2021/03/09/bill-gates-bitcoin-crypto-climate-change/ |access-date=30 July 2021 |website=Forbes |language=en}}{{Cite news |last1=Huang |first1=Jon |last2=O'Neill |first2=Claire |last3=Tabuchi |first3=Hiroko |author-link=Hiroko Tabuchi |date=3 September 2021 |title=Bitcoin Uses More Electricity Than Many Countries. How Is That Possible? |language=en-US |work=The New York Times |url=https://www.nytimes.com/interactive/2021/09/03/climate/bitcoin-carbon-footprint-electricity.html |access-date=1 March 2022 |issn=0362-4331}}{{cite web |title=Bitcoin energy consumption worldwide 2017-2021 |url=https://www.statista.com/statistics/881472/worldwide-bitcoin-energy-consumption/ |access-date=1 March 2022 |website=Statista |language=en}}

A study in 2015 investigated the global electricity usage that can be ascribed to Communication Technology (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.{{Cite journal |last1=Andrae |first1=Anders |last2=Edler |first2=Tomas |date=2015 |title=On Global Electricity Usage of Communication Technology: Trends to 2030 |journal=Challenges |language=en |volume=6 |issue=1 |pages=117–157 |doi=10.3390/challe6010117 |issn=2078-1547|doi-access=free}} 50px Text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License]

The healthcare sector produces 4.4–4.6% of global greenhouse gas emissions.{{cite journal |last1=J. Eckelman |first1=Matthew |last2=Huang |first2=Kaixin |last3=Dubrow |first3=Robert |last4=D. Sherman |first4=Jodi |date=December 2020 |title=Health Care Pollution And Public Health Damage In The United States: An Update |journal=Health Affairs |volume=39 |issue=12 |pages=2071–2079 |doi=10.1377/hlthaff.2020.01247 |pmid=33284703 |doi-access=free}}

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.{{cite journal |last1=Eckelman |first1=Matthew J. |last2=Sherman |first2=Jodi D. |title=Estimated Global Disease Burden From US Health Care Sector Greenhouse Gas Emissions |journal=American Journal of Public Health |date=April 2018 |volume=108 |issue=S2 |pages=S120–S122 |doi=10.2105/AJPH.2017.303846 |pmid=29072942 |pmc=5922190 |language=en |issn=0090-0036}}

{{Main|Environmental impact of war}}

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.{{cite web |title=Guest Article: CCPI x Military Emissions Gap – How Military Emissions Impact Global Warming |url=https://ccpi.org/guest-article-ccpi-x-military-emissions-gap-how-military-emissions-impact-global-warming/ |website=Climate change performance index |access-date=3 January 2025}}{{cite book |last1=Cottrell |first1=Linsey |last2=Parkinson |first2=Stuart |title=Estimating the Military’s Global Greenhouse Gas Emissions |date=November 2022 |publisher=Scientists for Global Responsibility (SGR) Conflict and Environment Observatory (CEOBS) |page=8 |url=https://ceobs.org/wp-content/uploads/2022/11/SGRCEOBS-Estimating_Global_MIlitary_GHG_Emissions_Nov22_rev.pdf |access-date=10 January 2025}}

{{excerpt|WASH#Reducing greenhouse gas emissions|paragraphs=1|file=no}}

According to UNEP, global tourism is a significant contributor to the increasing concentrations of greenhouse gases in the atmosphere.{{cite web |title=Environmental Impacts of Tourism – Global Level |url=http://www.unep.org/resourceefficiency/Business/SectoralActivities/Tourism/TheTourismandEnvironmentProgramme/FactsandFiguresaboutTourism/ImpactsofTourism/EnvironmentalImpacts/EnvironmentalImpactsofTourism-GlobalLevel/tabid/78777/Default.aspx |publisher=UNEP}}

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

File:CO2 Emissions from Electricity Production IPCC.png{{cite web|title=IPCC Working Group III – Mitigation of Climate Change, Annex III: Technology – specific cost and performance parameters – Table A.III.2 (Emissions of selected electricity supply technologies (gCO₂-eq/kWh))|url=https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf#page=7|publisher=IPCC|access-date=14 December 2018|page=1335|year=2014|archive-date=14 December 2018|archive-url=https://web.archive.org/web/20181214164438/https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf#page=7|url-status=live}}]]

File:UNECE 2020 Lifecycle Emissions.png

{{Excerpt|Life-cycle greenhouse gas emissions of energy sources|paragraphs=1-2|file=no}}

{{multiple image |total_width=500

| image1= 2019 Carbon dioxide emissions by income group - Oxfam data.svg |caption1= This pie chart illustrates both total emissions for each income group, and emissions per person within each income group. For example, the 10% with the highest incomes are responsible for half of carbon emissions, and its members emit an average of more than five times as much per person as members of the lowest half of the income scale.{{cite book |title=Climate Equality: a Climate for the 99% |date=November 2023 |publisher=Oxfam International |url=https://webassets.oxfamamerica.org/media/documents/cr-climate-equality-201123-en.pdf |archive-url=https://web.archive.org/web/20231123191311/https://webassets.oxfamamerica.org/media/documents/cr-climate-equality-201123-en.pdf |archive-date=23 November 2023 |url-status=live }} Fig. ES.2, Fig. ES.3, Box 1.2.

|image2=2021 CO2 emissions by income decile - International Energy Agency IEA.svg |caption2=Though total {{CO2}} emissions (size of pie charts) differ substantially among high-emitting regions, the pattern of higher income classes emitting more than lower income classes is consistent across regions. The world's top 1% of emitters emit over 1000 times more than the bottom 1%.{{cite web |last1=Cozzi |first1=Laura |last2=Chen |first2=Olivia |last3=Kim |first3=Hyeji |title=The world's top 1% of emitters produce over 1000 times more {{CO2}} than the bottom 1% |url=https://www.iea.org/commentaries/the-world-s-top-1-of-emitters-produce-over-1000-times-more-co2-than-the-bottom-1 |website=iea.org |publisher=International Energy Agency (IEA) |archive-url=https://web.archive.org/web/20230303032020/https://www.iea.org/commentaries/the-world-s-top-1-of-emitters-produce-over-1000-times-more-co2-than-the-bottom-1 |archive-date=3 March 2023 |date=22 February 2023 |url-status=live }} "Methodological note: ... The analysis accounts for energy-related CO₂, and not other greenhouse gases, nor those related to land use and agriculture."

}}

File:2021 Carbon dioxide (CO2) emissions per person versus GDP per person - scatter plot.svg countries emit more {{CO2}} per person than poorer (developing) countries.{{cite news |last1=Stevens |first1=Harry |title=The United States has caused the most global warming. When will China pass it? |url=https://www.washingtonpost.com/climate-environment/interactive/2023/global-warming-carbon-emissions-china-us/ |newspaper=The Washington Post |date=1 March 2023 |archive-url=https://web.archive.org/web/20230301130719/https://www.washingtonpost.com/climate-environment/interactive/2023/global-warming-carbon-emissions-china-us/ |archive-date=1 March 2023 |url-status=live }} Emissions are roughly proportional to GDP per person, though the rate of increase diminishes with average GDP/pp of about $10,000.]]

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.{{Cite journal |last1=Ritchie |first1=Hannah |last2=Roser |first2=Max |last3=Rosado |first3=Pablo |date=2020-05-11 |title={{CO2}} and Greenhouse Gas Emissions |url=https://ourworldindata.org/co2-emissions |journal=Our World in Data}} Almost half of the increase in absolute global emissions has been caused by the richest 10% of the population.Rapid Transition Alliance, 13 April 2021 [https://www.rapidtransition.org/wp-content/uploads/2021/04/Cambridge-Sustainability-Commission-on-Scaling-behaviour-change-report.pdf "Cambridge Sustainability Commission Report on Scaling Behaviour Change"] {{Webarchive|url=https://web.archive.org/web/20220205165843/https://www.rapidtransition.org/wp-content/uploads/2021/04/Cambridge-Sustainability-Commission-on-Scaling-behaviour-change-report.pdf |date=2022-02-05 }} p. 20 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.Emission trends and drivers, Ch 2 in "Climate Change 2022: Mitigation of Climate Change". http://www.ipcc.ch. Retrieved 5 April 2022.[https://report.ipcc.ch/ar6wg3/pdf/IPCC_AR6_WGIII_SummaryForPolicymakers.pdf Climate Change 2022] ipcc.ch{{Webarchive|url=https://web.archive.org/web/20220404160950/https://report.ipcc.ch/ar6wg3/pdf/IPCC_AR6_WGIII_SummaryForPolicymakers.pdf |date=4 April 2022}} 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.{{cite journal |last1=Wiedmann |first1=Thomas |last2=Lenzen |first2=Manfred |last3=Keyßer |first3=Lorenz T. |last4=Steinberger |first4=Julia K. |date=19 June 2020 |title=Scientists' warning on affluence |journal=Nature Communications |language=en |volume=11 |issue=1 |pages=3107 |bibcode=2020NatCo..11.3107W |doi=10.1038/s41467-020-16941-y |issn=2041-1723 |pmc=7305220 |pmid=32561753}}{{cite journal |last1=Nielsen |first1=Kristian S. |last2=Nicholas |first2=Kimberly A. |last3=Creutzig |first3=Felix |last4=Dietz |first4=Thomas |last5=Stern |first5=Paul C. |author3-link=Felix Creutzig |date=30 September 2021 |title=The role of high-socioeconomic-status people in locking in or rapidly reducing energy-driven greenhouse gas emissions |journal=Nature Energy |language=en |volume=6 |issue=11 |pages=1011–1016 |bibcode=2021NatEn...6.1011N |doi=10.1038/s41560-021-00900-y |issn=2058-7546 |s2cid=244191460|doi-access=free }}

According to a 2020 report by Oxfam and the Stockholm Environment Institute,{{Cite web |last=Gore |first=Tim |date=2020-09-23 |title=Confronting carbon inequality |url=https://www.oxfam.org/en/research/confronting-carbon-inequality |url-status=live |archive-url=https://web.archive.org/web/20220324062107/https://www.oxfam.org/en/research/confronting-carbon-inequality |archive-date=24 March 2022 |access-date=2022-03-20 |website=Oxfam International |language=en}}{{cite web |last1=Kartha |first1=Sivan |last2=Kemp-Benedict |first2=Eric |last3=Ghosh |first3=Emily |last4=Nazareth |first4=Anisha |last5=Gore |first5=Tim |date=September 2020 |title=The Carbon Inequality Era: An assessment of the global distribution of consumption emissions among individuals from 1990 to 2015 and beyond |url=https://www.sei.org/wp-content/uploads/2020/09/research-report-carbon-inequality-era.pdf |url-status=live |archive-url=https://web.archive.org/web/20220122094405/http://www.sei.org/wp-content/uploads/2020/09/research-report-carbon-inequality-era.pdf |archive-date=22 January 2022 |access-date=11 May 2022 |work=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.{{cite news |last1=Clifford |first1=Catherine |date=26 January 2021 |title=The '1%' are the main drivers of climate change, but it hits the poor the hardest: Oxfam report |language=en |work=CNBC |url=https://www.cnbc.com/2021/01/26/oxfam-report-the-global-wealthy-are-main-drivers-of-climate-change.html |url-status=live |access-date=28 October 2021 |archive-url=https://web.archive.org/web/20211028161800/https://www.cnbc.com/2021/01/26/oxfam-report-the-global-wealthy-are-main-drivers-of-climate-change.html |archive-date=28 October 2021}}{{cite web |last1=Berkhout |first1=Esmé |last2=Galasso |first2=Nick |last3=Lawson |first3=Max |last4=Rivero Morales |first4=Pablo Andrés |last5=Taneja |first5=Anjela |last6=Vázquez Pimentel |first6=Diego Alejo |date=25 January 2021 |title=The Inequality Virus |url=https://www.oxfam.org/en/research/inequality-virus |url-status=live |archive-url=https://web.archive.org/web/20211028161802/https://www.oxfam.org/en/research/inequality-virus |archive-date=28 October 2021 |access-date=28 October 2021 |website=Oxfam International |language=en}}{{cite web |date=2021 |title=Emissions Gap Report 2020 / Executive Summary |url=https://wedocs.unep.org/bitstream/handle/20.500.11822/34438/EGR20ESE.pdf |url-status=live |archive-url=https://web.archive.org/web/20210731143517/https://wedocs.unep.org/bitstream/handle/20.500.11822/34438/EGR20ESE.pdf |archive-date=31 July 2021 |website=United Nations Environment Programme |at=p. XV Fig. ES.8}} This was, respectively, during that period, 15% of cumulative emissions compared to 7%.{{cite web |last1=Paddison |first1=Laura |date=28 October 2021 |title=How the rich are driving climate change |url=https://www.bbc.com/future/article/20211025-climate-how-to-make-the-rich-pay-for-their-carbon-emissions |url-status=live |archive-url=https://web.archive.org/web/20211105220537/https://www.bbc.com/future/article/20211025-climate-how-to-make-the-rich-pay-for-their-carbon-emissions |archive-date=5 November 2021 |access-date=7 November 2021 |work=BBC |language=en}} 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.{{cite journal |last1=Oswald |first1=Yannick |last2=Owen |first2=Anne |last3=Steinberger |first3=Julia K. |date=March 2020 |title=Large inequality in international and intranational energy footprints between income groups and across consumption categories |url=http://eprints.whiterose.ac.uk/156055/3/Submission%2520manuscript%25202.05%2520Y.O.%2520A.O.%2520J.K.S%5B1%5D.pdf |url-status=live |journal=Nature Energy |language=en |volume=5 |issue=3 |pages=231–239 |bibcode=2020NatEn...5..231O |doi=10.1038/s41560-020-0579-8 |issn=2058-7546 |archive-url=https://web.archive.org/web/20211028093113/https://eprints.whiterose.ac.uk/156055/3/Submission%20manuscript%202.05%20Y.O.%20A.O.%20J.K.S%5b1%5d.pdf |archive-date=28 October 2021 |access-date=16 November 2021 |s2cid=216245301}} However, wealthy individuals are also often shareholders and typically have more influence{{cite news |last1=Timperley |first1=Jocelyn |title=Who is really to blame for climate change? |language=en |work=www.bbc.com |url=https://www.bbc.com/future/article/20200618-climate-change-who-is-to-blame-and-why-does-it-matter |access-date=8 June 2022}} and, especially in the case of billionaires, 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".{{cite journal |last1=Zheng |first1=Heran |last2=Long |first2=Yin |last3=Wood |first3=Richard |last4=Moran |first4=Daniel |last5=Zhang |first5=Zengkai |last6=Meng |first6=Jing |last7=Feng |first7=Kuishuang |last8=Hertwich |first8=Edgar |last9=Guan |first9=Dabo |date=March 2022 |title=Ageing society in developed countries challenges carbon mitigation |url=https://www.researchgate.net/publication/359121007 |journal=Nature Climate Change |language=en |volume=12 |issue=3 |pages=241–248 |bibcode=2022NatCC..12..241Z |doi=10.1038/s41558-022-01302-y |issn=1758-6798 |s2cid=247322718 |url-access=subscription |hdl-access=free |hdl=11250/3027882}}

{{See also|Methane emissions#Approaches to reduce emissions}}

Governments have taken action to reduce greenhouse gas emissions to mitigate climate change. Countries and regions listed in Annex I of the United Nations Framework Convention on Climate Change (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.

{{cite book |url=http://unfccc.int/resource/docs/2011/sbi/eng/inf01.pdf |title=Compilation and synthesis of fifth national communications. Executive summary. Note by the secretariat. |publisher=United Nations Framework Convention on Climate Change (UNFCCC) |year=2011 |location=Geneva (Switzerland) |pages=9–10}}

{{Rp|3}} Policies implemented by governments include for example national and regional targets to reduce emissions, promoting energy efficiency, and support for an energy transition.{{excerpt|Climate change mitigation|paragraphs=1-2|file=no}}

File:Figure 3 from US Energy Information Administration IEO2023 report.png

{{See also|Carbon budget|Climate change scenario}}In October 2023, the US Energy Information Administration (EIA) released a series of projections out to 2050 based on current ascertainable policy interventions.

{{cite book

| author = EIA

| title = International Energy Outlook 2023

| date = October 2023

| publisher = US Energy Information Administration (EIA)

| location = Washington DC, USA

| url = https://www.eia.gov/outlooks/ieo/pdf/IEO2023_Narrative.pdf

| access-date = 2023-10-11

}} Informally describes as a "narrative" and tagged IEO2023.

{{cite web

| author = EIA

| title = International Energy Outlook 2023 — Landing page

| date = 11 October 2023

| work = US Energy Information Administration (EIA)

| location = Washington DC, USA

| url = https://www.eia.gov/outlooks/ieo/index.php

| access-date = 2023-10-13

}} Landing page.

{{cite AV media

| author = CSIS

| title = US EIA's International Energy Outlook 2023

| date = 11 October 2023

| publisher = Center for Strategic and International Studies (SCIS)

| location = Washington DC, USA

| url = https://www.youtube.com/watch?v=o0ARuBDrE_o

| access-date = 2023-10-13

}} 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 net{{nbhyph}}zero in 2050. A{{nbsp}}sensitivity analysis varied key parameters, primarily future GDP growth (2.6%{{nnbsp}}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 figure{{nbsp}}3 plot). The IEO2023 exploration provides a benchmark and suggests that far stronger action is needed.

{{Excerpt|Climate change mitigation#Needed emissions cuts|file=no}}

{{Pie chart

| caption= Global carbon dioxide emissions by country in 2023:

| other = yes

| label1 = China

| value1 = 34 | color1=#E33

| label2 = United States

| value2 = 12 | color2=#1A9

| label3 = India

| value3 = 7.6 | color4=#CC5

| label4 = European Union

| value4 = 6.4 | color3=#36A

| label5 = Russia

| value5 = 5.3 | color5=#E72

| label6 = Japan

| value6 = 2.4 | color6=#928

| label7 = Iran

| value7 = 2.0

}}

In 2023, China, the United States, India, EU, Russia, Japan, and Iran - the world's largest {{CO2}} emitters - together accounted for 69.7% of total global fossil {{CO2}} emissions.{{cite web |author=Crippa, M.; Guizzardi, D.; Pagani, F.; Banja, M.; Muntean, M.; Schaaf, E.; Monforti-Ferrario, F.; Becker, W.E.; Quadrelli, R.; Risquez Martin, A.; Taghavi-Moharamli, P.; Köykkä, J.; Grassi, G.; Rossi, S.; Melo, J.; Oom, D.; Branco, A.; San-Miguel, J.; Manca, G.; Pisoni, E.; Vignati, E.; Pekar, F. |url=https://edgar.jrc.ec.europa.eu/report_2024?vis=co2tot#data_download |title=GHG emissions of all world countries – 2024 |publisher=Publications Office of the European Union |location=Luxembourg |year=2024 |doi=10.2760/4002897 |access-date=2024-09-18}}

{{See also|List of countries by carbon dioxide emissions|List of countries by carbon dioxide emissions per capita|List of countries by greenhouse gas emissions|List of countries by greenhouse gas emissions per capita}}

{{sticky table start}}

{{Excerpt|List of countries by carbon dioxide emissions|section=Fossil carbon dioxide emissions by country|paragraphs=1}}

{{sticky table end}}

File:1990- Annual greenhouse gas emissions - U.S. - line chart.svg

{{excerpt|Greenhouse gas emissions by the United States|paragraphs=1|file=no|only=paragraphs}}

{{excerpt|Greenhouse gas emissions by China|paragraphs=1|only=paragraphs}}

{{excerpt|Climate change in India#Greenhouse gas emissions|paragraphs=1-2|file=no|only=paragraphs}}

{{Main|Impact of the COVID-19 pandemic on the environment#Climate change}}

In 2020, carbon dioxide emissions fell by 6.4% or 2.3 billion tonnes globally.{{cite journal |vauthors=Tollefson J |date=January 2021 |title=COVID curbed carbon emissions in 2020 - but not by much |journal=Nature |volume=589 |issue=7842 |pages=343 |bibcode=2021Natur.589..343T |doi=10.1038/d41586-021-00090-3 |pmid=33452515 |s2cid=231622354}} In April 2020, {{NOx}} emissions fell by up to 30%.{{cite journal |display-authors=6 |vauthors=Forster PM, Forster HI, Evans MJ, Gidden MJ, Jones CD, Keller CA, Lamboll RD, Quéré CL, Rogelj J, Rosen D, Schleussner CF, Richardson TB, Smith CJ, Turnock ST |date=August 2020 |title=Erratum: Publisher Correction: Current and future global climate impacts resulting from COVID-19 |journal=Nature Climate Change |volume=10 |issue=10 |page=971 |doi=10.1038/s41558-020-0904-z |pmc=7427494 |pmid=32845944}} In China, lockdowns and other measures resulted in a 26% decrease in coal consumption, and a 50% reduction in nitrogen oxide emissions.{{cite journal |vauthors=Rume T, Islam SM |date=September 2020 |title=Environmental effects of COVID-19 pandemic and potential strategies of sustainability |journal=Heliyon |volume=6 |issue=9 |pages=e04965 |doi=10.1016/j.heliyon.2020.e04965 |doi-access=free |pmc=7498239 |pmid=32964165|bibcode=2020Heliy...604965R }} 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.{{cite journal |display-authors=6 |vauthors=Forster PM, Forster HI, Evans MJ, Gidden MJ, Jones CD, Keller CA, Lamboll RD, Le Quéré C, Rogelj J, Rosen D, Schleussner CF |date=7 August 2020 |title=Current and future global climate impacts resulting from COVID-19 |journal=Nature Climate Change |language=en |volume=10 |issue=10 |pages=913–919 |bibcode=2020NatCC..10..913F |doi=10.1038/s41558-020-0883-0 |issn=1758-6798 |doi-access=free|url=https://eprints.whiterose.ac.uk/164227/7/Covid_emissions_paperV3_clean_supplementary.pdf }}

{{Portal|Climate change|Environment|Renewable Energy}}

• {{annotated link|Arctic methane emissions}}
• {{annotated link|Carbon offsets and credits}}
• {{annotated link|List of locations and entities by greenhouse gas emissions}}
• {{annotated link|Low-carbon economy}}
• {{annotated link|Net zero emissions}}
• {{annotated link|World energy supply and consumption}}

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{{Reflist}}

{{Commons category|Greenhouse gas emissions}}

• [https://unfccc.int/ghg-inventories-annex-i-parties/2025 Latest official greenhouse gas emissions data of developed countries] from the UNFCCC
• [https://di.unfccc.int/time_series Earlier official greenhouse gas emissions data of developed countries] from the UNFCCC
• [http://www.cmdl.noaa.gov/aggi/ Annual Greenhouse Gas Index (AGGI)] from NOAA
• [http://www.cmdl.noaa.gov/ccgg/iadv/ NOAA CMDL CCGG – Interactive Atmospheric Data Visualization] NOAA {{CO2}} data
• [http://ipcc.ch IPCC Website]
• [https://www.ipcc.ch/assessment-report/ar6/ Official IPCC Sixth Assessment Report website]

{{Climate change}}

{{Anthropogenic effects on the environment}}

{{Authority control}}

{{World topic|Greenhouse gas emissions by|title=Greenhouse gas emissions by country|noredlinks=yes|state=show}}

{{World topic|Climate change in|title=Climate change by country|noredlinks=yes|state=show}}

{{DEFAULTSORT:Greenhouse Gas}}

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Category:Climate forcing

Category:Climate change