Greenhouse gas emissions

Greenhouse gas emissions are greenhouse gases vented to the Earth's atmosphere because of humans: the greenhouse effect of their 50 billion tons[1] a year causes climate change. Most is carbon dioxide from burning fossil fuels: coal, oil and natural gas. The largest polluters include coal in China and large oil and gas companies, many state-owned by OPEC and Russia. Human caused emissions have increased atmospheric carbon dioxide by about 50%.

Greenhouse Gas Emissions by Economic Sector according to IPCC Fifth Assessment Report[citation needed]

Electricity generation and transport are large emitters.

Deforestation and other changes in land use also emit carbon dioxide and methane.[2][3] The largest source of anthropogenic methane emissions is agriculture, closely followed by gas venting and fugitive emissions from the fossil-fuel industry.[4][5] The largest agricultural methane source is livestock. Agricultural soils emit nitrous oxide partly due to fertilizers.[6] Similarly, fluorinated gases from refrigerants play an outsized role in total human emissions.

At current emission rates, before 2030 temperatures may have increased by 1.5 °C (2.7 °F),[7][8] which is the limit for the G7 countries[9] and aspirational limit of the Paris Agreement.

Measurements and calculations

Carbon dioxide, methane, nitrous oxide (N
) and three groups of fluorinated gases (sulfur hexafluoride (SF
), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs)) are the major anthropogenic greenhouse gases, and are regulated under the Paris Agreement.[10]:147[11]

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. Note that ozone depletion has only a minor role in greenhouse warming, though the two processes often are 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.[12][13][14]

There are several ways of measuring greenhouse gas emissions. Some variables that have been reported include:[15]

  • 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 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: Contribution of a given greenhouse gas is reported as a CO
    equivalent. The calculation to determine this takes into account how long that gas remains in the atmosphere. This is not always known accurately[clarification needed] and calculations must be regularly updated to reflect new information.
  • What sectors are included in the calculation (e.g., energy industries, industrial processes, agriculture etc.): There is often a conflict between transparency and availability of data.[citation needed]
  • 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.[16]

These measures are sometimes used by countries to assert various policy/ethical positions on climate change.[17]: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.[15]

Emissions may be measured over long time periods. This measurement type is called historical or cumulative emissions. Cumulative emissions give some indication of who is responsible for the build-up in the atmospheric concentration of greenhouse gases.[18]:199

The national accounts balance would be positively related to carbon emissions. The national accounts balance shows the difference between exports and imports. For many richer nations, such as the United States, the accounts balance is negative because more goods are imported than they are exported. This is mostly due to the fact that it is cheaper to produce goods outside of developed countries, leading the economies of developed countries to become increasingly dependent on services and not goods. We believed that a positive accounts balance would means that more production was occurring in a country, so more factories working would increase carbon emission levels.[19]

Emissions may also be measured across shorter time periods. Emissions changes may, for example, be measured against a 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).[10]: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.[20]:370 Per capita emissions may be based on historical or annual emissions.[17]:106–107

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.[21]


Modern global CO2 emissions from the burning of fossil fuels.

Since about 1750 human activity has increased the concentration of carbon dioxide and other greenhouse gases. As of 2021, measured atmospheric concentrations of carbon dioxide were almost 50% higher than pre-industrial levels.[22] Natural sources of carbon dioxide are more than 20 times greater than sources due to human activity,[23] but over periods longer than a few years natural sources are closely balanced by natural sinks, mainly photosynthesis of carbon compounds by plants and marine plankton. As a result of this balance, the atmospheric mole fraction of carbon dioxide remained between 260 and 280 parts per million for the 10,000 years between the end of the last glacial maximum and the start of the industrial era.[24] Absorption of terrestrial infrared radiation by longwave absorbing gases such as these greenhouse gases make Earth a less efficient emitter. Therefore, in order for Earth to emit as much energy as is absorbed, global temperatures must increase.

Burning fossil fuels is estimated to have emitted 62% of 2015 human GhG.[25]

The main sources of greenhouse gases due to human activity are:

The seven sources of CO
from fossil fuel combustion are (with percentage contributions for 2000–2004):[28]

This list needs updating, as it uses an out of date source.[needs update]

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.[29][30]

Emissions by sector

2016 global greenhouse gas emissions by sector.[31] Percentages are calculated from estimated global emissions of all Kyoto Greenhouse Gases, converted to CO2 equivalent quantities (GtCO2e).

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 global warming, and helps in understanding the changes required to mitigate climate change.

Manmade 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.[32]

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.[33] 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.[34] 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.[32] Around 6% of emissions are fugitive emissions, which are waste gases released by the extraction of fossil fuels.

As of 2020 Secunda CTL is the world's largest single emitter, at 56.5 million tonnes CO2 a year.[35]

Mean greenhouse gas emissions for different food types[36]
Food Types Greenhouse Gas Emissions (g CO2-Ceq per g protein)
Ruminant Meat
Recirculating Aquaculture
Trawling Fishery
Non-recirculating Aquaculture
Non-trawling Fishery
Starchy Roots

Traditional rice cultivation is the second biggest agricultural methane source after livestock, with a near-term warming impact equivalent to the carbon-dioxide emissions from all aviation.[37]


Approximately 3.5% of the overall human impact on climate are from the aviation sector. The impact of the sector on climate in the late 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.[38]

Buildings and construction

In 2018, manufacturing construction materials and maintaining buildings accounted for 39% of carbon dioxide emissions from energy and process-related emissions. Manufacture of glass, cement, and steel accounted for 11% of energy and process-related emissions.[39] 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.[40] 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 emissionsa popular type is the passive house.[39]

Digital sector

The digital sector produces between 2% and 4% of global GHG emissions.[41] However the sector reduces emissions from other sectors which have a larger global share, such as transport of people,[42][43] and possibly buildings and industry.[44]

Electricity generation

Coal-fired power stations are the single largest emitter, with over 20% of global GhG in 2018.[45] Although much less polluting than coal plants, natural gas-fired power plants are also major emitters.[46] taking electricity generation as a while over 25% in 2018.[47]


Plastic is produced mainly from fossil fuels. Plastics are estimated to emit between 1% and 2% of global GhG over their lifecycle.[48] The EPA estimates[49] 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,[50] the transportation produce greenhouse gases also.[51] 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.[52][53]

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 plastic will contribute greenhouse gases in the equivalent of 850 million tonnes of carbon dioxide (CO2) to the atmosphere in 2019. In current trend, annual emissions will grow to 1.34 billion tonnes by 2030. By 2050 plastic could emit 56 billion tonnes of Greenhouse gas emissions, as much as 14 percent of the Earth's remaining carbon budget.[54] 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.[55]

Sanitation sector

Wastewater as well as sanitation systems are known to contribute to greenhouse-gas emissions (GHG)[quantify] mainly through the breakdown of excreta during the treatment process. This results in the generation of methane gas, that is then released into the environment. Emissions from the sanitation and wastewater sector have been focused mainly on treatment systems, particularly treatment plants, and this accounts for the bulk of the carbon footprint for the sector.[56]

In as much as climate impacts from wastewater and sanitation systems present global risks, low-income countries experience greater risks in many cases. In recent years,[when?] attention to adaptation needs within the sanitation sector is just beginning to gain momentum.[57]


According to UNEP, global tourism is closely linked to climate change. Tourism is a significant contributor to the increasing concentrations of greenhouse gases in the atmosphere. Tourism accounts for about 50% of traffic movements.[citation needed] Rapidly expanding air traffic contributes about 2.5% of the production of CO
. The number of international travelers is expected to increase from 594 million in 1996 to 1.6 billion by 2020, adding greatly to the problem unless steps are taken to reduce emissions.[58][needs update]

Trucking and haulage

The trucking and haulage industry plays a part in production of CO
, contributing around 20% of the UK's total carbon emissions a year, with only the energy industry having a larger impact at around 39%.[59][globalize] Average carbon emissions within the haulage industry are falling—in the thirty-year period from 1977 to 2007, the carbon emissions associated with a 200-mile journey fell by 21 percent.[60][globalize]

By socio-economic class

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. Almost half of the increase in absolute global emissions has been caused by the richest 10% of the population.[61]

By energy source

Life cycle CO2 equivalent (including albedo effect) from selected electricity supply technologies according to IPCC 2014.[62][63] Arranged by decreasing median (gCO
eq/kWh) values.
Currently commercially available technologies
Gascombined cycle410490650
Biomass – Dedicated130230420
Solar PV – Utility scale1848180
Solar PV – rooftop264160
Concentrated solar power8.82763
Wind Offshore8.01235
Wind Onshore7.01156
Pre‐commercial technologies
Ocean (Tidal and wave)5.61728
1 see also environmental impact of reservoirs#Greenhouse gases.

Relative CO
emission from various fuels

One liter of gasoline, when used as a fuel, produces 2.32 kg (about 1300 liters or 1.3 cubic meters) of carbon dioxide, a greenhouse gas. One US gallon produces 19.4 lb (1,291.5 gallons or 172.65 cubic feet).[64][65][66]

Mass of carbon dioxide emitted per quantity of energy for various fuels[67]
Fuel name CO

(lbs/106 Btu)


Natural gas 117 50.30 181.08
Liquefied petroleum gas 139 59.76 215.14
Propane 139 59.76 215.14
Aviation gasoline 153 65.78 236.81
Automobile gasoline 156 67.07 241.45
Kerosene 159 68.36 246.10
Fuel oil 161 69.22 249.19
Tires/tire derived fuel 189 81.26 292.54
Wood and wood waste 195 83.83 301.79
Coal (bituminous) 205 88.13 317.27
Coal (sub-bituminous) 213 91.57 329.65
Coal (lignite) 215 92.43 332.75
Petroleum coke 225 96.73 348.23
Tar-sand bitumen [citation needed] [citation needed] [citation needed]
Coal (anthracite) 227 97.59 351.32

Regional and national attribution of emissions

From land-use change

Greenhouse gas emissions from agriculture, forestry and other land use, 1970–2010.

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.[68] 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.[17]:92–93

There are substantial uncertainties in the measurement of net carbon emissions.[69] Additionally, there is controversy over how carbon sinks should be allocated between different regions and over time.[17]:93 For instance, concentrating on more recent changes in carbon sinks is likely to favour those regions that have deforested earlier, e.g., Europe.

Greenhouse gas intensity

Carbon intensity of GDP (using PPP) for different regions, 1982–2011

Greenhouse gas 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.[70] Emission intensities may be calculated using market exchange rates (MER) or purchasing power parity (PPP).[17]:96 Calculations based on MER show large differences in intensities between developed and developing countries, whereas calculations based on PPP show smaller differences.

Cumulative and historical emissions

Cumulative energy-related CO
emissions between the years 1850–2005 grouped into low-income, middle-income, high-income, the EU-15, and the OECD countries.
Cumulative energy-related CO
emissions between the years 1850–2005 for individual countries.
Map of cumulative per capita anthropogenic atmospheric CO
emissions by country. Cumulative emissions include land use change, and are measured between the years 1950 and 2000.
Regional trends in annual CO
emissions from fuel combustion between 1971 and 2009.
Regional trends in annual per capita CO
emissions from fuel combustion between 1971 and 2009.

Cumulative anthropogenic (i.e., human-emitted) emissions of CO
from fossil fuel use are a major cause of global warming,[71] and give some indication of which countries have contributed most to human-induced climate change.[72]:15 Overall, developed countries accounted for 83.8% of industrial CO
emissions over this time period, and 67.8% of total CO
emissions. Developing countries accounted for industrial CO
emissions of 16.2% over this time period, and 32.2% of total CO
emissions. The estimate of total CO
emissions includes biotic carbon emissions, mainly from deforestation.[17]:94 calculated per capita cumulative emissions based on then-current population. The ratio in per capita emissions between industrialized countries and developing countries was estimated at more than 10 to 1.

Including biotic emissions brings about the same controversy mentioned earlier regarding carbon sinks and land-use change.[17]: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.

Non-OECD countries accounted for 42% of cumulative energy-related CO
emissions between 1890 and 2007.[73]:179–80 Over this time period, the US accounted for 28% of emissions; the EU, 23%; Russia, 11%; China, 9%; other OECD countries, 5%; Japan, 4%; India, 3%; and the rest of the world, 18%.[73]:179–80

Changes since a particular base year

Between 1970 and 2004, global growth in annual CO
emissions was driven by North America, Asia, and the Middle East.[74] The sharp acceleration in CO
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.[28] In comparison, methane has not increased appreciably, and N
by 0.25% y−1.

Using different base years for measuring emissions has an effect on estimates of national contributions to global warming.[72]:17–18[75] 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.[72]:17–18 Within the G8 group of countries, it is most significant for the UK, France and Germany. These countries have a long history of CO
emissions (see the section on Cumulative and historical emissions).

Annual emissions

Annual per capita emissions in the industrialized countries are typically as much as ten times the average in developing countries.[10]: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).[76] 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.[76] Emissions in Russia and Ukraine have decreased fastest since 1990 due to economic restructuring in these countries.[77]

Energy statistics for fast growing economies are less accurate than those for the industrialized countries. For China's annual emissions in 2008, the Netherlands Environmental Assessment Agency estimated an uncertainty range of about 10%.[76]

The greenhouse gas footprint refers to the emissions resulting from the creation of products or services. It is more comprehensive than the commonly used carbon footprint, which measures only carbon dioxide, one of many greenhouse gases.

2015 was the first year to see both total global economic growth and a reduction of carbon emissions.[78]

Top emitter countries

The top 40 countries emitting all greenhouse gases, showing both that derived from all sources including land clearance and forestry and also the CO2 component excluding those sources. Per capita figures are included. "World Resources Institute data".. Note that Indonesia and Brazil show very much higher than on graphs simply showing fossil fuel use.

In 2019, China, the United States, India, the EU27+UK, Russia and Japan - the world’s largest CO2 emitters - together accounted for 51% of the population, 62.5% of global gross domestic product, 62% of total global fossil fuel consumption and emitted 67% of total global fossil CO2. Emissions from these five countries and the EU28 show different changes in 2019 compared to 2018: the largest relative increase is found for China (+3.4%), followed by India (+1.6%). On the contrary, the EU27+UK (-3.8%), the United States (-2.6%), Japan (-2.1%) and Russia (-0.8%) reduced their fossil CO2 emissions.[79]

2019 Fossil CO2 emissions by country[79]
Countrytotal emissions
per capita
per GDP
GLOBAL TOTAL38,016.57100.004.930.29
 United States5,107.2613.4315.520.25
International Shipping730.261.92--
 South Korea651.871.7112.700.30
International Aviation627.481.65--
 Saudi Arabia614.611.6218.000.38
 South Africa494.861.308.520.68
 United Kingdom364.910.965.450.12
 Italy,  San Marino and the Holy See331.560.875.600.13
 France and  Monaco314.740.834.810.10
 Spain and Andorra259.310.685.580.13
 United Arab Emirates222.610.5922.990.34
 Serbia and Montenegro70.690.197.550.44
 Israel and  Palestine68.330.187.960.18
 Hong Kong44.020.125.880.10
 North Korea42.170.111.640.36
  Switzerland and  Liechtenstein39.370.104.570.07
 New Zealand38.670.108.070.18
 Bosnia and Herzegovina33.500.099.570.68
 Trinidad and Tobago32.740.0923.810.90
 Sri Lanka27.570.071.310.10
 Dominican Republic27.280.072.480.14
 Sudan and  South Sudan22.570.060.400.13
 New Caledonia15.660.0455.251.67
 Côte d’Ivoire13.560.040.530.10
 Costa Rica8.980.021.800.09
 North Macedonia8.920.024.280.26
 El Salvador7.
 Papua New Guinea4.070.010.470.11
 Puerto Rico3.910.011.070.04
 Burkina Faso3.640.010.180.08
 Equatorial Guinea3.470.012.550.14
 Democratic Republic of the Congo2.980.010.030.03
 Sierra Leone1.400.000.180.10
 Cabo Verde1.020.001.830.26
 French Guiana0.610.002.06-
 French Polynesia0.600.002.080.10
 The Gambia0.590.000.270.11
 Antigua and Barbuda0.510.004.900.24
 Central African Republic0.490.000.100.11
 Cayman Islands0.400.006.380.09
 Saint Lucia0.300.001.650.11
 Western Sahara0.300.000.51-
 Saint Kitts and Nevis0.190.003.440.14
 São Tomé and Príncipe0.160.000.750.19
 Saint Vincent and the Grenadines0.150.001.320.11
 Solomon Islands0.
 Turks and Caicos Islands0.130.003.700.13
 British Virgin Islands0.120.003.770.17
 Saint Pierre and Miquelon0.060.009.72-
 Cook Islands0.040.002.51-
 Falkland Islands0.030.0010.87-
 Saint Helena,  Ascension and  Tristan da Cunha0.020.003.87-
Per capita anthropogenic greenhouse gas emissions by country for the year 2000 including land-use change.
Global carbon dioxide emissions by country in 2015.
The C-Story of Human Civilization by PIK

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.[80] 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.[73]:179[81]: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.

Davis and Caldeira (2010)[81]:4 found that a substantial proportion of CO
emissions are 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. Based on annual emissions data from the year 2004, and on a per-capita consumption basis, the top-5 emitting countries were found to be (in tCO
per person, per year): Luxembourg (34.7), the US (22.0), Singapore (20.2), Australia (16.7), and Canada (16.6).[81]:5 [needs update]Carbon Trust research revealed that approximately 25% of all CO
emissions from human activities 'flow' (i.e., are imported or exported) from one country to another.[citation needed] Major developed economies were found to be typically net importers of embodied carbon emissions—with UK consumption emissions 34% higher than production emissions, and Germany (29%), Japan (19%) and the US (13%) also significant net importers of embodied emissions.[82][needs update]

Effect of policy

Governments have taken action to reduce greenhouse gas emissions to mitigate climate change. Assessments of policy effectiveness have included work by the Intergovernmental Panel on Climate Change,[83] International Energy Agency,[84][85] and United Nations Environment Programme.[86] Policies implemented by governments have included[87][88][89] national and regional targets to reduce emissions, promoting energy efficiency, and support for a renewable energy transition such as Solar energy as an effective use of renewable energy because solar uses energy from the sun and does not release pollutants into the air.

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.[89]:3 Analysis by the UNFCCC (2011)[89]:8 suggested that policies and measures undertaken by Annex I Parties may have produced emission savings of 1.5 thousand Tg CO
in the year 2010, with most savings made in the energy sector. The projected emissions saving of 1.5 thousand Tg CO
-eq is measured against a hypothetical "baseline" of Annex I emissions, i.e., projected Annex I emissions in the absence of policies and measures. The total projected Annex I saving of 1.5 thousand CO
-eq does not include emissions savings in seven of the Annex I Parties.[89]:8

Due to the COVID-19 pandemic, there was a significant reduction in CO
emissions globally in 2020.


A wide range of projections of future emissions have been produced.[90] Unless energy policies change substantially, the world will continue to depend on fossil fuels until 2025–2030.[91][92] Projections suggest that more than 80% of the world's energy will come from fossil fuels. This conclusion was based on "much evidence" and "high agreement" in the literature.[92] Projected annual energy-related CO
emissions in 2030 were 40–110% higher than in 2000, with two-thirds of the increase originating in developing countries.[92] Projected annual per capita emissions in developed country regions remained substantially lower (2.8–5.1 tonnes CO
) than those in developed country regions (9.6–15.1 tonnes CO
).[93] Projections consistently showed increase in annual world emissions of "Kyoto" gases,[94] measured in CO
) of 25–90% by 2030, compared to 2000.[92]

See also


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