The US and climate change – on track to fulfill its international obligation?

by Dr. Simon Schaub

Climate change represents one of the most polarized issues in the United States (Smith et al. 2024) and the upcoming presidential elections in November will probably be decisive for future climate action in the US. For long, the US has been a laggard on climate change. Major progress in federal climate policy has only been made in recent years, especially in years with governments led by the Democratic Party: under Barack Obama’s presidency between 2009 and 2017 and most recently under the presidency of Joe Biden since 2021. However, Donald Trump’s presidency between 2017 and 2021 came with a severe backlash on federal climate action (Bomberg, 2021) and there is strong indication that a second Trump presidency would revoke much the US has achieved in recent years (Smith, 2024).

This post sheds light on recent US climate policies and whether these resulted in CO2 emissions reduction. It further provides an outlook on what the upcoming presidential elections mean for future climate action in the US.

Global obligation to mitigate climate change

The Paris Agreement in 2015 and countries’ promise to try to limit global temperatures to 1.5°C above pre-industrial levels have been a landmark for international climate action. However, achieving this target still requires fast and deep decarbonization efforts, especially from countries with high carbon emissions, such as the US (Abraham‐Dukuma et al., 2022).

In fact, the US has a major obligation to reduce greenhouse gas (GHG) emissions. Historically, the US has emitted the largest share of CO2 emissions among all countries in the world with about one quarter of cumulative CO2 emissions since 1750 (Andrew & Peters, 2023; Ritchie et al., 2023). This also holds true relative to the country’s size of population. The average American citizen has had the highest ‘carbon footprint’ worldwide throughout the 20th century and per capita, CO2 emissions are globally still one of the highest with 14.9t in 2022. In comparison, the average citizen in Germany and China emitted 8t of CO2 in the same year and the UK has reduced its per capita emissions to 4.7t, which is equal to the 2022 world average (Andrew & Peters, 2023; Ritchie et al., 2023).

What have the US promised to do?

In the aftermath of the Paris Agreement, countries defined emission reduction targets in their Nationally Determined Contributions (NDC). In its most recent NDC submitted in 2021, the US promised to reduce their GHG emissions by 50 – to 52% below 2005 levels by 2030. The NDC explicitly addresses all GHG emissions, including methane, and emissions from all sectors (U.S. Government, 2021). The Climate Action Tracker (CAT) rates the U.S.’s target as “almost sufficient”: it is not ambitious enough to help achieve the 1.5°C target but would be sufficient in achieving a maximum of 2°C of global warming. To be able to meet the 1.5°C target, the CAT suggests, based on future emission projections, that the US would need to reduce their GHG emissions by at least 62%–65% below 2005 levels by 2030 (Climate Analytics & NewClimate Institute, 2023).

For a long time, the US has avoided setting themselves verifiable absolute emission reduction targets (such as the one now defined in their NDC). Nevertheless, they have steadily adopted more ambitious targets over time. International conferences have led countries to define GHG emission reduction targets. High-income countries, such as Germany or the UK, adopted first targets following the Kyoto Protocol (adopted in 1997). The US never ratified the protocol and consequently did not define ‘absolute’ emission reduction targets in the aftermath of the international treaty. Despite this, the US announced a first international target in 2002. However, it was a ‘relative’ emission reduction target to reduce their emission intensity (GHG emissions divided by GDP). This can be seen as less ambitious as it still allowed absolute emissions to increase given strong economic growth. Following the Conference of Parties in Copenhagen in 2009, the US, under President Obama, defined their first absolute target with 17% GHG emission reduction compared to 2005 levels by 2020. Still under Obama’s presidency, the US submitted their second absolute emission reduction target when they ratified the Paris Agreement in 2015. The target aimed at achieving 26–28% emission reduction below 2005 levels by 2025. It has been replaced by the 2030 target of the updated NDC from 2021 (Climate Analytics & NewClimate Institute, 2023).

Finally, the US developed a long-term emission reduction strategy in 2021 that foresees achieving net zero emissions by 2050 at the latest. Net zero still allows GHG emissions if these are sufficiently absorbed by the atmosphere, for instance through forests or carbon capture and storage.

What climate policies have been adopted?

The US has steadily developed a climate policy portfolio to reduce GHG emissions and achieve their climate targets, both at the federal and the state level. Figure 1 provides an overview of federal climate policies adopted since 2000.

Key federal climate policies include the 2005 Energy Policy Act and the 2009 American Recovery and Reinvestment Act. These two primarily aimed at increasing renewable energy production and improving energy efficiency (Le Quéré et al., 2019; Pischke et al., 2018). The 2015 Clean Power Plan is another crucial federal climate policy to induce state-level policies to expand renewable energy and reduce emissions from coal and oil power plants (Grant et al., 2014; Pischke et al., 2018).

Figure 1. Climate legislation and climate policies adopted by the executive branch of government. Data source: Grantham Research Institute and Climate Policy Radar (2023).

Since the start of the Biden presidency in 2021, the US has significantly advanced its climate policy by adopting ambitious climate legislation and several executive regulations (Smith, 2024).

Legislation includes the Bipartisan Infrastructure Law (BIL) and the Inflation Reduction Act (IRA). The BIL, enacted in 2021, provides several measures to promote renewable energy expansion, including investments to improve the energy infrastructure and deploy energy storage systems (Climate Analytics & NewClimate Institute, 2023). The IRA, enacted in 2022, mobilizes the highest level of climate investment in US history (USD 370bn) mainly to foster renewable energies and further reduce emissions from energy and heat production. The money will be used to stimulate development and deployment of renewable energies through tax credits, grants, and loans. It further provides funding to explicitly reduce methane emissions (Barichella, 2023; Climate Analytics & NewClimate Institute, 2023; Jensen & Grieger, 2022; Smith, 2024)

The Biden administration has further enacted several regulations that aim at improving energy efficiency in buildings (energy efficiency standards), in the energy industry (emission limits for fossil-fuel fired plants, and in the transport sector (emission standards for vehicles). In addition, in March 2024, the Biden administration proposed regulation to significantly expand the production of electronic vehicles (Climate Analytics & NewClimate Institute, 2023; Smith, 2024).

Some of the state governments have proactively developed their own climate policy portfolios. Among those with most ambitious climate policy are New York, California, Maine, and Massachusetts (Bergquist & Warshaw, 2023).

Emissions pathway across sectors

The US has been successful in reducing their CO2 emissions, both absolute as well as relative to the size of their economy and their population. Per capita emissions already peaked in 1973 (23.1 tons per capita) and have significantly declined since (14.9 tons per capita in 2022). Absolute CO2 emissions peaked in 2007 after the economic crisis (6.13bn tons) and have since declined steadily (5.06bn tons in 2022) (Andrew & Peters, 2023; Ritchie et al., 2023).

Figure 2. CO2 emissions by sector. Data source: IEA (2023).

The decline in absolute CO2 emissions in the US is mostly due to emission reduction in electricity and heat production. Similar to most other countries in the world, this sector has contributed most to the US’s historical CO2 emissions (see Figure 2 for an overview). The US has been successful in significantly decreasing emissions from energy production, with a 30 % reduction between 2005 and 2019. The decrease can be traced back to a significant reduction in the combustion of coal and oil and a strong uptake of natural gas and renewable energy (Jensen & Grieger, 2022). Emissions from all other sectors have remained mostly stable over time. Transport has been responsible for the second largest share of CO2 emissions. Since 2019, emissions from transport have even been equally high or higher than those from energy generation.

The US still has a long way to go to even come close to achieving their most recent emission reduction target of 50-52% emission reduction compared to 2005 levels by 2030 and to deliver their share to achieving at least a maximum of 2°C global warming. As of 2022, the US has achieved about one third of their targeted emission reduction with only eight more years to go (Climate Analytics & NewClimate Institute, 2023).

Have climate policies helped reducing emissions?

Evidence on single federal policies suggests that especially the 2005 Energy Policy Act and the 2009 American Recovery and Reinvestment Act were important for increasing renewable energy generation and improving energy efficiency (Le Quéré et al., 2019; Pischke et al., 2018). Furthermore, studies indicate that the 2015 Clean Power Plan increased renewable energy and reduced emissions from coal and oil power plants (Grant et al., 2014; Pischke et al., 2018). It is also telling that those policies primarily targeted electricity and heat production, which is the sector that has predominantly reduced CO2 emissions.

Presumably, a few years pass by until the effect of policies on emission reduction is visible and it will thus be interesting to observe whether the BIL and the IRA as well as associated regulations adopted by the Biden administration will further reduce GHG emissions in the future.

Apart from evidence on single policies, country comparative studies indicate that adopting climate policies in general helps reducing GHG emissions (Eskander & Fankhauser, 2020; Le Quéré et al., 2019). In a recent study conducted by a research team I was part of (still under review), we studied countries that have contributed the highest share of CO2 emissions (OECD and BRICS countries) and could confirm such a positive effect of climate policies. In fact, we show that countries that have been more active in adopting climate policies (i.e. higher ‘policy density’) were more successful in decoupling CO2 emissions from economic growth. Figure 3 shows that the US has adopted more and more climate policies over time, whereas carbon emission intensity declined steadily (i.e. the economy as a whole has become more efficient in terms of CO2 emissions when producing and using energy).

Figure 3. Association between climate policy and carbon emission intensity. Data sources: IEA (2024) and Grantham Research Institute and Climate Policy Radar (2023).

Our study further suggests that in countries that adopt emission reduction targets, such as the US, climate policies are even more effective in reducing CO2 emissions.

Will the US achieve its climate targets after the presidential elections in November?

Reaching its 2030 climate target will be challenging for the US with the existing climate policy portfolio (Barichella, 2023). Much will depend on the upcoming presidential election. A second Trump presidency is predestined in resulting in another severe setback on climate action. During his first presidency, Trump withdrew from the Paris Agreement, immediately revoked existing climate legislation, undermined administrative structures (most importantly the Environmental Protection Agency), and cut budgets for climate research (Tosun & Schaub, 2024). Trump has already announced that he would immediately eliminate the IRA’s tax credits for renewable energy (which, however, would necessitate a Republican majority in the US Congress), has condemned plans to incentivize electrical vehicles, and has indicated that he would heavily increase oil and gas exploration if elected president again (Smith, 2024). If Biden wins the election and the Democrats are able to secure majorities in the US Congress, there is a high chance that the US will continue its increasingly ambitious climate policy efforts and might achieve its emission reduction target.

About the Author

Simon Schaub is a research fellow at the Institute of Political Science at Heidelberg University. He studies the politics of environmental issues, with a special focus on public policy, determinants of environmental policy-making and individual environmental attitudes. He is part of the ERC-funded collaborative project DeepDCarb on climate politics.

Funding was generously provided by the ERC (via the DeepDCarb Advanced Grant 882601).


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Header: Photo by dmncwndrlch,

Figure 1-3: Created by the author

Cite this blog post
Simon Schaub (2024, May 29). The US and climate change – on track to fulfill its international obligation? HCA Graduate Blog. Retrieved June 17, 2024, from

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1 Response

  1. Céline Guilleux says:

    Dear Hypotheses blogger,

    We found your article particularly interesting. To increase its visibility so the community can more easily appreciate it, we made it a headline article on portal.

    Best regards,
    The Hypotheses team

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