Global Non-CO₂ Greenhouse Gas
Emission Projections & Mitigation Potential:
2020-2080
(EPA-430-R-25-002)

About this Report

Published in January 2025, the EPA technical report Global Non-CO₂ Greenhouse Gas Emission Projections & Mitigation Potential: 2020-2080 provides a consistent and comprehensive set of historical and projected estimates of emissions and technical and economic mitigation estimates of non-CO₂ GHGs from anthropogenic sources for 195 countries. The analysis provides information that can be used to understand national contributions of GHG emissions, historical progress on reductions, and mitigation opportunities.

This report is the latest installment of the U.S. Environmental Protection Agency’s (EPA’s) non-carbon dioxide (non-CO₂) greenhouse gas (GHG) assessments and combines two long-running EPA report series: Non-CO₂ Greenhouse Gases: International Emissions and Projections and Global Mitigation of Non-CO₂ Greenhouse Gases. This update reflects new modeling, updated baselines, and new mitigation options.

This web-based summary is intended to provide a brief summary of the abatement potential and costs of implementing specific abatement technologies.

Overview

Non-CO₂ Greenhouse Gases

Non-CO₂ greenhouse gases are more potent than CO₂ (per unit weight) at trapping heat within the atmosphere. Global warming potential (GWP) is the factor that quantifies the heat trapping potential of each GHG relative to that of carbon dioxide (CO₂). For example, methane has a GWP value of 28 which means that each molecule of methane released into the atmosphere is 28 times as effective at trapping heat compared to an equivalent unit of CO₂. Additionally, some non-CO₂ GHGs can remain in the atmosphere for longer periods of time than CO₂. The table shows the list of GHG gases with their GWP values that are considered in this report.

Greenhouse Gas GWP Factor (100-yr)
CO₂ 1
CH₄ 28
N₂O 265
HFCs 4 - 12,400
NF₃ 16,100
SF₆ 23,500
PFCs 6,630 - 17,400

Emission Projections and Mitigation Assessments

The projections were generated using a combination of country-reported inventory data supplemented with EPA-estimated calculations consistent with inventory guidelines of the Intergovernmental Panel on Climate Change (IPCC). Historical emission estimates were incorporated from country-reported data from 1990 through 2020, and emissions were projected through 2080. The projections results are a “business-as-usual” (BAU) scenario with emission rates consistent with historical levels and do not include future effects of policy changes.

The EPA estimates that global non-CO₂ GHG emissions in 2020 totaled approximately 12,730 MtCO₂e. When added to a global CO₂ emission estimate for 2020 of approximately 33,500 MtCO₂e, anthropogenic non-CO₂ emissions represent 28% of the global GHG emissions emitted annually on a CO₂ equivalent basis in 2020.

Explore Summary:

The mitigation estimates were generated using a bottom-up, engineering cost approach that analyzed the costs of a wide range of mitigation technologies and incorporated them into an economic tool called a marginal abatement cost (MAC) curve. MAC curves provide information on the amount of emissions reductions relative to the BAU scenario that can be achieved as well as an estimate of the costs of implementing the GHG abatement measures.

Explore Summary:

The EPA estimates that global non-CO₂ GHG emissions in 2015 totaled approximately 12,010 MtCO₂e. When added to a global CO₂ emission estimate for 2015 of approximately 36,000 MtCO₂e, anthropogenic non-CO₂ emissions represent 25% of the global GHG emissions emitted annually on a CO₂ equivalent basis in 2015.

Energy Overview

The energy sector is the second largest contributing sector to global emissions of non-CO₂ GHGs, accounting for 23% of global non-CO₂ emissions in 2020. Global energy-sector CH₄ and N₂O historical and projected emissions and mitigation potential are estimated for the following source categories:

  • Coal mining (CH₄)
  • Natural gas and oil systems (CH₄)
  • Combustion of fossil fuels and biomass (CH₄, N₂O)

Energy sector emissions increased 20% between 1990 and 2020. Between 2015 and 2030, global energy-sector emissions are projected to increase 4% under a BAU scenario, reaching 3,056 MtCO₂e in 2030. Natural gas and oil activities are projected to remain the largest contributor to non-CO₂ emissions from the energy sector; stationary and mobile combustion emissions are projected to grow 18% between 2020 and 2030. Emissions from coal mining activities are projected to decrease by 5% between 2020 and 2030 as the energy sector transitions from coal to natural gas.

Mitigation potential from the energy sector is approximately 1,249 MtCO₂e in 2030, accounting for 64% of coal emissions and 55% of oil and gas emissions. Mitigation potential in the energy sector represents 31% of total global non-CO₂ mitigation potential in 2030.

Industrial Processes Overview

The industrial processes sector is the fourth largest contributing sector to global emissions of non-CO₂GHGs, accounting for 10% of emissions in 2015. F-GHGs are important because the gases tend to have large heat-trapping capacities and long atmospheric lifetimes. This section presents global N₂O and F-GHG (SF₆, PFCs, SF₆, and NF₃) historical and projected emissions and mitigation potential from the industrial processes sector, including the following categories:

  • Nitric and adipic acid production (N₂O)
  • Electronics (HFCs, PFCs, SF₆, NF₃)
  • Electric power systems (EPS) (SF₆)
  • Metals (PFCs, SF₆)
  • Substitutes for ozone-depleting substances (ODSs) (HFCs)
  • HCFC-22 production (HFCs)

As the fastest growing sector, industrial processes’ emissions are projected to increase 30% between 2020 and 2030. These baseline projections include reductions from countries that have ratified the Kigali Amendment to the Montreal Protocol.

Mitigation potential from the industrial processes sector is estimated to be approximately 475 MtCO₂e in 2030. This mitigation potential is 25% of the industrial processes sector’s emissions in that year.

Agriculture Overview

The agriculture sector is the largest contributing sector to global emissions of non-CO₂ GHGs, accounting for over 50% of emissions in 2020. Global agriculture-sector CH₄ and N₂O historical and projected emissions and the mitigation potential are estimated from the following source categories:

  • Livestock (CH₄, N₂O)
  • Croplands (CH₄, N₂O)
  • Rice cultivation (CH₄, N₂O)

Between 2020 and 2030, global agriculture-sector emissions are projected to increase 5%, reaching 6,787 MtCO₂e in 2030.

Mitigation potential from the agriculture sector is estimated to be approximately 1279 MtCO₂e in 2030. This mitigation potential is 9%, 28%, and 44% of livestock, croplands, and rice cultivation emissions, respectively; 19% of overall agriculture-sector emissions; and 31% of total global non-CO₂ mitigation potential in that year.

Waste Overview

The waste sector is the third largest contributing sector to global emissions of non-CO₂ GHGs, accounting for 15% of global non-CO₂ emissions in 2020. Global waste-sector CH₄ and N₂O historical and projected emissions and the mitigation potential are estimated from the following source categories:

  • Landfills (CH₄)
  • Wastewater (CH₄, N₂O)

Between 2020 and 2030, emissions from landfills are projected to grow more quickly than emissions from wastewater, increasing 29% compared with 6% growth for wastewater. During this time period, global waste-sector emissions are projected to increase 20% under a BAU scenario, reaching 2,244 MtCO₂e in 2030. Increases in population and per capita waste generation drive global waste emissions upward, but historical implementation of waste-related regulations and gas recovery and use has tempered this increase.

Mitigation potential from the waste sector is estimated to be approximately 1045 MtCO₂e in 2030. This mitigation potential is 55% and 30% of landfill and wastewater emissions, respectively; 47% of waste-sector emissions; and 26% of total global non-CO₂ mitigation potential in that year.

Top 5 Emitters

In addition to global results, throughout this report each source category discussion includes information on baseline projections and mitigation potential for top emitting countries.

Emission Projections and Mitigation Potential

This figure shows the total BAU emission projections (dashed line), and residual emissions by sector at various user selectable price points. The figure shows that over time non-CO₂ emissions can be greatly reduced by deploying available mitigation technologies (i.e. at higher costs). These emissions that remain after mitigation options are implemented are called “residual” emissions. Achieving long-term reductions of non-CO₂ emissions below the 2020 level would require development of new or more effective mitigation technologies.

Coal Mining

CH₄ is produced during the process of coalification, where vegetation is converted by geological and biological forces into coal. Coal seams and the surrounding rock strata store CH₄. Natural erosion, faulting, or mining can reduce pressure above or surrounding the coal bed and liberate the CH₄. Because CH₄ is explosive, the gas must be removed from underground mines high in CH₄ as a safety precaution.

From 2020 through 2030, CH₄ emissions from coal mining are projected to decrease by about 5%. In 2030, the adoption of the suite of abatement measures considered in this analysis can reduce total annual emissions from coal mining by approximately 64%. The MAC curve analysis results show that 81% of potential CH₄ abatement is achievable at prices below $10/tCO₂e. At or below a break-even price of $20, 97% of abatement potential is technically feasible.

Oil and Natural Gas Systems

CH₄ is the principal component of natural gas and is emitted during natural gas production, processing, transmission, and distribution. Oil production and processing upstream of oil refineries can also emit CH₄ in significant quantities as natural gas is often found in conjunction with petroleum deposits. In both systems, CH₄ is a fugitive emission from leaking equipment, system upsets, deliberate flaring and venting at production fields, processing facilities, natural gas transmission lines and compressor stations, natural gas storage facilities, and natural gas distribution lines.

From 2020 through 2030, CH₄ emissions from natural gas and oil systems are projected to increase by about 3%. The abatement potential is projected to increase over time to 725 MtCO₂e in 2030. In 2030, abatement measures could reduce emissions by 58% at break-even prices of $20 or below. However, in 2030, 79% of potential abatement is estimated to cost more than $50/tCO₂e, suggesting that achieving these reductions would be difficult without reducing the cost of abatement or improving the removal efficiency of available abatement measures.

Combustion of Fossil Fuels and Biomass

CH₄ and N₂O emissions result from the combustion of fossil fuels and biomass in both stationary and mobile sources. CH₄ emissions are primarily a function of the CH₄ content of the fuel and the overall combustion efficiency. N₂O emissions vary according to the type of fuel, combustion technology, size and vintage, pollution control equipment used, and maintenance and operating practices.

Mitigation options for the combustion of fossil fuels and biomass in both stationary and mobile sources were not included in this report.

Nitric and Adipic Acid Production

Nitric acid is an inorganic compound used primarily to make synthetic commercial fertilizer. Adipic acid is a white crystalline solid used as a feedstock in the manufacture of synthetic fibers, coatings, plastics, urethane foams, elastomers, and synthetic lubricants. The production of these acids results in N₂O emissions as a by-product.

Emissions from nitric acid production are estimated to increase by 31% between 2020 and 2030. The global emission reduction potential in the nitric and adipic acid production source category is 187 MtCO₂e in 2030, or 79% of projected baseline emissions from nitric and adipic acid production. Roughly 80% of the abatement potential is achievable at break-even prices between $0 and $20, demonstrating that low breakeven prices can have a substantial impact on reducing emissions from this source category.

Electronics

Electronics consists of emissions from the manufacturing of semiconductors, flat panel displays (FPDs), and photovoltaics (PV). During the manufacture of these electronics, F-GHGs, including HFCs, PFCs, SF₆, and NF₃, are emitted from two repeated activities: (1) cleaning of chemical vapor deposition chambers and (2) plasma etching (etching intricate patterns into successive layers of films and metals).

Between 1990 and 2020, emissions from electronics manufacturing increased by 581%. From 2020 through 2030, emissions from FPD manufacturing are estimated to increase by 83%. From 2020 through 2030, emissions from semiconductor manufacturing are estimated to increase by 134% primarily because of the increased demand for electronic goods and the growing complexity of semiconductor devices. Projected emissions from the solar PV industry nearly quadruple from 2020 through 2030. Abatement potential in the electronics source category is estimated to be 104 MtCO₂e, 61% of the baseline emissions. Implementing abatement measures in the electronics source category can be relatively inexpensive, with over 63% of mitigatable emissions achievable at $5/MtCO₂e or less, with the large majority of those abatable emissions coming from flat panel display manufacturing.

Electric Power Systems

SF₆ is used for absorption of energy from electric currents flowing between conductors and as an insulating medium in electric power systems. SF₆ emissions occur through leakage and handling losses.

Overall, global SF₆ from electric power systems emissions increased by 79% from 1990 through 2020 despite a downward trend in the mid-1990s.

Significant reductions are available at a low cost in the electric power systems source category. For example, nearly 43% of abatement potential can be achieved at break-even prices less than $0/tCO₂e. Emission reduction technologies that cost up to $10/tCO₂e can reduce 100% of technologically feasible emission reductions in 2030, 53 MtCO₂e.

Metals

Emissions from metal production include PFCs emitted as by-products of aluminum production and SF₆ emitted from magnesium production.

From 1990 through 2020, combined PFC and SF₆ emissions from metal production decreased by 71%. Emissions from metal production are projected to increase by 34% between 2020 and 2030, with varying growth across emissions from aluminum production (39% increase) and magnesium production (10% increase). The metals source category emits less than 1% of the global baseline emissions in 2030, making this source a small emitter relative to the others.

Metals production’s abatement potential is estimated to be approximately 17 MtCO₂e in 2030, or 38% of the source's baseline emissions. Break-even prices as low as $5/tCO₂e can mitigate 85% of metals mitigatable emissions.

Substitutes for Ozone-Depleting Substances

HFCs are used as alternatives to several classes of ODSs that are being phased out under the terms of the Montreal Protocol. ODSs, which include chlorofluorocarbons (CFCs), halons, carbon tetrachloride, methyl chloroform, and HCFCs, have been used in a variety of industrial applications, including refrigeration and air-conditioning equipment (ref/AC), aerosols, solvent cleaning, fire extinguishing, foam production, and sterilization. HFCs are not harmful to the stratospheric ozone layer, but they are powerful GHGs.

Through 2030, emissions and consumption of HFCs are expected to grow in both developed and developing countries but will grow much more quickly in developing countries. In contrast to developing countries where emission increases are driven by growth in the amount of equipment used, emission increases in developed countries are driven primarily by the aging and replacement of existing ODS equipment.

Abatement of HFC emissions from this collection of sources is challenging given the available technology. This analysis estimates that available abatement technologies can only abate approximately 2% and 6% of emissions from fire protection and foam-related emissions respectively. Abatement potential in emissions from solvent use is less than 1%. Abatement potential in emissions from aerosols is 3% of aerosol-related emissions because of readily available ways to remove aerosols from consumer products.

Emissions from ref/AC contribute to 90% of baseline emissions from the ODS substitutes category and are also the largest source of potential abatement. Abatement measures targeting ref/AC emissions have the potential to abate 49 MtCO₂e of emissions, which represents 4% of baseline ref/AC emissions.

HCFC-22 Production

Trifluoromethane (HFC-23) is generated and emitted as a byproduct during the production of chlorodifluoromethane (HCFC-22). HCFC-22 is used primarily as a feedstock for production of synthetic polymers and in emissive applications, primarily ref/AC.

The global abatement potential for the HCFC-22 production source category is estimated to rise over time. In 2020, the maximum abatement potential is 121 MtCO₂e. However, abatement potential is expected to decrease to 68 MtCO₂e in 2030, but then increase steadily through the rest of the model time horizon. Maximum abatement potential can be achieved at little or no cost; all the potential can be reached with break-even prices below $5/tCO₂e.

Livestock

Emissions from livestock include enteric fermentation and manure management. Enteric fermentation is a normal mammalian digestive process, where gut microbes produce CH₄ that the animal exhales. Livestock manure management produces CH₄ emissions during the anaerobic decomposition of manure and N₂O emissions during the nitrification and denitrification of the organic nitrogen content in livestock manure and urine.

From 2020 through 2030, emissions from enteric fermentation and manure management are projected to increase 12% and 5%, respectively. Livestock populations, which are driven by demand for animal products such as meat and milk, dominate emission projections. Developing countries are expected to increase their livestock populations.

Technologically feasible global abatement potential from livestock is estimated at 358 MtCO₂e in 2030, a 9% reduction compared with the baseline. The total abatement potential is expected steadily rise as a percentage of baseline emissions through 2050. In 2030, 6% of emission reductions are achievable at break-even prices below $0.

Croplands

A number of land management activities add nitrogen to soils, thus increasing the amount of N₂O emitted, including various cropping practices and livestock waste management. Indirect additions of nitrogen occur through volatilization and atmospheric deposition of ammonia and oxides of nitrogen that originate from (1) the application of fertilizers and livestock wastes onto agricultural land and (2) surface runoff and leaching of nitrogen from these same sources.

From 2020 through 2030, N₂O emissions from agricultural soils are projected to increase by 6%. Globally, croplands are responsible for about 2,000 MtCO₂e of emissions in 2030. Of these emissions, technology is available to mitigate 28%, or about 560 MtCO₂e. In 2030, 67% of potential mitigation is available at break-even prices below $0/tCO₂e. Additional reductions are possible with the inclusion of more costly abatement measures. For example, mitigation potential increases to 78% by including abatement measures with an implementation cost less than or equal to $50/tCO₂e.

Rice

Rice cultivation consists of CH₄ emissions from rice production. The anaerobic decomposition of organic matter (i.e., decomposition in the absence of free oxygen) in flooded rice fields produces CH₄. When fields are flooded, aerobic decomposition of organic material gradually depletes the oxygen present in the soil and flood water, causing anaerobic conditions in the soil to develop. Once the environment becomes anaerobic, CH₄ is produced through anaerobic decomposition of soil organic matter by methanogenic bacteria. Several factors influence the amount of CH₄ produced, including water management practices and the quantity of organic material available to decompose.

Rice cultivation is projected to account for 6% of total non-CO₂ emissions by 2030. From 2020 through 2030, emissions are expected to remain flat.

In 2030, roughly half of the available abatement can be achieved at relatively low prices. Approximately 4% of the potential abatement, can be abated at prices below $0/tCO₂e in 2030 with an additional 45% reduction from baseline available at prices between $0 and $20/tCO₂e.

Landfills

Landfilling of solid waste includes emissions associated with the disposal of municipal solid waste (MSW) and industrial solid waste. Landfills produce CH₄ and other landfill gases, primarily CO₂, through the natural process of bacterial decomposition of organic waste under anaerobic conditions.

Global abatement potential from municipal solid waste landfills is estimated to be approximately 817 MtCO₂e in 2030, or 55% of the baseline emissions. Slightly more than half of all potential abatement can be achieved at break-even prices below $20/tCO₂e; 26% of reductions can be achieved at prices below $0/tCO₂e, suggesting a substantial share of abatement could generate revenue for landfill operators.

Wastewater

Wastewater originates from a variety of residential, commercial, and industrial sources. It can be a source of CH₄ when organic material present in the wastewater-flows decomposes under anaerobic conditions. Developed countries primarily rely on centralized aerobic wastewater treatment systems that limit CH₄ generation, while developing countries often rely on a broader suite of wastewater treatment technologies. N2O emissions occur primarily as indirect emissions from wastewater after disposal of effluent into waterways, lakes, or the sea.

Global wastewater emissions are projected to increase modestly, 6% from 2020 through 2030. The global abatement potential of CH₄ from wastewater treatment is 146 MtCO₂e in 2020 and rises to 228 MtCO₂e in 2030. High-cost abatement measures from wastewater treatment significantly constrain the abatement achievable at lower prices. Cost-effective emission reductions, or reduction at prices below $0, are less than 1% of BAU emissions in 2030.