USA

Historical emissions are based on the 1990-2024 inventory emissions developed by the University of Maryland’s Center for Global Sustainability, which uses AR5 Global Warming Potential (GWP) values (Desai et al., 2026).

In previous assessments, the CAT has used the US Environmental Protection Agency’s (EPA) official inventory. However, the EPA has not released an updated inventory since the Trump Administration assumed office in 2025. In September 2025, the EPA proposed to end its Greenhouse Gas Reporting Program (GHGRP), which requires energy and industrial facilities to track and report their direct GHG emissions and has been a crucial data source for the development of the EPA’s annual emissions inventory (U.S. Environmental Protection Agency, 2026b).

The Trump Administration has also withdrawn the US from the United Nations Framework Convention on Climate Change (UNFCCC) and the Intergovernmental Panel on Climate Change (IPCC), which will lead to significant gaps in global emissions inventories (The White House, 2026b).

Voided 2030 and 2035 NDC targets

For the 2030 NDC target, we apply the indicated target of 50%–52% reduction to the 2005 base year including LULUCF and then subtract the projected emissions for the LULUCF sector. The LULUCF emission projections in 2030 were taken from the 5th Biennial Report, which reported sinks of 0.6–0.8 GtCO₂e/year in 2030 (U.S. Department of State, 2022).

For the 2035 NDC target, we apply the indicated target of 61%-66% reduction to the 2005 base year including LULUCF and then subtract the projected emissions from the LULUCF sector. The LULUCF emission projections in 2030 were taken from the 5th Biennial Report, which reported sinks of 0.6–0.9 GtCO₂e/year in 2035 (U.S. Department of State, 2022).

Voided 2050 net zero target

For the net zero target, we assume total GHG emissions in 2050 are balanced by projected sinks in 2050. The LULUCF sinks in 2050 were taken from the US long-term strategy (LTS) submitted to the UNFCCC in November 2021 (U.S. Department of State, 2021). Since the document does not provide exact figures, we have extracted the approximated figures from the graphs in the report. The reading of the graphs results in an approximation of minus 0.6-1.4 GtCO₂e for LULUCF sinks in 2050; we add this sink to the residual estimate in 2050 to get 0.6-1.5 GtCO₂e in 2050. We include also estimates for 2040 in our pathway using a similar approach.

The CAT’s current policy projections, which inform the CAT’s rating of the US’ policies and actions, were developed using projections from the US Energy Information Agency (EIA), the US Environmental Protection Agency (EPA), and third-party independent studies. The quantification approach for the emissions projections’ upper and lower bounds is outlined in more detail below.

The upper bound of the CAT’s current policy projections was generated in three steps:

• First, we estimate the total emissions projections under current policies as the aggregation of the energy, industry, agriculture, and waste sectors:
  • GHG emissions in the energy sector:
    • Energy-related CO₂ emissions projections were generated using EIA data. Short-term projections (2024–2025) were taken from the EIA’s Short-term Outlook (STEO) from September 2026 (U.S. Energy Information Administration, 2026g). These projections are harmonised with long-term projections (2024–2035) taken from the EIA’s 2026 Annual Energy Outlook (AEO) Alternative Electricity and Alternative Transportation Combination scenario (U.S. Energy Information Administration, 2026a).
    • The 2026 AEO Alternative Electricity and Alternative Transportation Combination scenario considers the OBBB’s termination and restrictions on federal tax credits for decarbonising key sectors. The scenario also models the emissions impact of the EPA’s finalised and pending changes to emissions standards in the transport and power sector.
    • CH₄ and N₂O emissions projected using EPA's 2025 Global Non-CO₂ Greenhouse Gas Emission Projections & Mitigation Potential: 2020-2080 (U.S. Environmental Protection Agency, 2025a).
    • All GHG emissions in the energy sector result from the sum of the CO₂ and non-CO₂ estimates as described above. The resulting projections are harmonised to the latest historical year using growth rates.
  • GHG emissions in the industry sector: the projection of GHG emissions in industrial processes was calculated by type of industry and then aggregated.
    • Emissions from mineral, chemical, and metal industries were projected using the growth rates for each industry’s annual shipment value from the EIA’s 2025 AEO Reference Case scenario (2024) and 2026 AEO Alternative Electricity and Alternative Transportation Combination scenario (2025-2035) (U.S. Energy Information Administration, 2025a, 2026a).
    • Emissions from remaining industries were projected by using the growth rates for fluorinated gases from the EPA's 2025 Global Non-CO₂ Greenhouse Gas Emission Projections & Mitigation Potential: 2020-2080 to forecast emissions from 2023-2035 (U.S. Environmental Protection Agency, 2025a).
  • GHG emissions in the agriculture sector:
    • CH₄ and N₂O emissions projected using growth rates from the EPA's 2025 Global Non-CO₂ Greenhouse Gas Emission Projections & Mitigation Potential: 2020-2080 to forecast emissions from 2025-2035 (U.S. Environmental Protection Agency, 2025a).
  • GHG emissions in the waste sector:
    • CH₄ and N₂O emissions projected using growth rates from the EPA's 2025 Global Non-CO₂ Greenhouse Gas Emission Projections & Mitigation Potential: 2020-2080 to forecast emissions from 2025-2035 (U.S. Environmental Protection Agency, 2025a).
• Second, each of the above emissions categories was harmonised to historical data for each sector by applying the estimated annual percentage change from the projected dataset to the base year. The projections for all sectors were then aggregated to obtain total GHG emissions, excluding LULUCF.
• Third, the quantification of the One Big Beautiful Bill Act’s (OBBB) impact on non-CO₂ GHG emissions, which are not accounted for in the EPA’s 2025 Global Non-CO₂ Greenhouse Gas Emission Projections & Mitigation Potential: 2020-2080:
  • The OBBB’s interventions in the energy, industry, agriculture, and waste sectors will increase non-CO₂ GHG emissions. To account for the increase in non-CO₂ emissions, we used projections from Princeton University’s REPEAT Project (REPEAT) (Jenkins et al., 2025).
  • Determined the percent change between the non-CO₂ emissions projections from REPEAT’s “Biden-Era Mid Range” scenario (which assumes the continuation of the Biden Administration’s climate policy package until 2035) and the “OBBB Final” scenario.
  • Applied the percent change to the combined, economy-wide non-CO₂ emissions projections for the energy, industry, agriculture, and waste sectors (described above) and then calculated the absolute difference between the economy-wide non-CO₂ emissions projections and the post-OBBB non-CO₂ emissions projections.
  • Conservatively delayed the OBBB’s impact on emissions until 2026. As a result of the OBBB, non-CO₂ emissions increase by 119 MTCO₂e in 2030.

The lower bound of the current policy projections was developed using an external scenario:

• Economy-wide emissions projections from the Rhodium Group’s Taking Stock 2026 report were used to inform the lower bound of the CAT’s emissions projections range (Kolus et al., 2026). Specifically, we base the projection's lower bound on the report’s “Low” emissions scenario, which quantifies the CO₂ and non-CO₂ emissions impact of the OBBB and major executive actions (including executive orders on energy and climate, as well as finalised and pending rule changes to emissions standards in the transport and power sectors). For the projections from 2024 to 2025, we use the approach outlined in the three steps for the projections’ upper bound. Using 2025 as the base year, we harmonised the Rhodium Group’s “Low” scenario by applying the scenario's estimated annual percentage change.