Most have understood that from a climate perspective, Kamala Harris would be preferential to Donald Trump as the next President of the USA. But just how big is the difference, and what does it consist of? Mattias Goldmann lays it out for us, in five key areas, including a comparison between Harris and the current president Biden.

1. Climate targets. Harris will keep Biden’s climate targets of minus 50-52% by 2030 compared to 2005 and net zero by 2050 – the global benchmark to stand a chance to keep global warming within the limits set by the Paris Agreement. Key policy instruments to deliver on these targets include the Inflation Reduction Act (IRA), described below, but they are not enough to fully reach the targets – further measures are needed and expected both at federal and state levels.

Trump has called climate change “a hoax“, his presidential platform doesn’t have any climate targets and his campaign focuses on rolling back the key policies that reduce emissions. Carbon Brief’s calculations show that even with Trump, emissions would go down, with around 28% below 2005 levels by 2030 – since renewable energy, electric vehicles etc are hard to stop.

2. Climate budget. Harris aims to continue Biden’s Inflation Reduction Act (IRA), the biggest climate package in the world, ever, with grants, loans and tax credits of at least USD $369bn for clean energy, electric vehicles, green hydrogen, low-carbon manufacturing and “climate-smart” agriculture. Other significant Biden initiatives are more stringent vehicle fuel standards, standards on energy efficiency, rules on methane emissions from oil and gas, and power plant greenhouse gas emissions, several of them just recently finalized.

Trump has been very vocal against the IRA, calling it the “biggest tax hike in history” and promising to cancel it and instead increase investment in fossil fuels. At the Republican Party nomination in July 2024, Trump promised to stop Biden’s “green scam” and use the “trillions of dollars” on roads instead. Harris vows to instead increase the climate and green energy spending to 10 trillion USD over the next ten years.

3. Energy. This is the sector where the differences are the most pronounced, both between Harris and Trump and between Harris and current president Biden. The Republican party manifesto contains the headline “drill, baby, drill” to clarify their intention to make the US more energy independent through increased production of fossil fuels, primarily coal and oil through fracking. In 2020, the Trump administration cancelled restrictions on methane emissions from the oil and gas industry as well as energy efficiency regulations.

Harris aims to continue the Biden administration’s focus on renewable energy, but with stricter targets – while Biden pledged to decarbonize the electricity grid by 2035, Harris’ aim is a carbon-neutral grid by 2030. Harris also wants to ban offshore drilling and fracking, whilst Biden (and Obama before him) was against such bans. Harris vows to stop subsidizing fossil fuels, and in her 2019 presidential candidate campaign vowed to introduce a “climate pollution fee” on industries, with the majority of the income going back to green community projects. She has also been backing native Indians against pipelines for fossil fuels.

As San Francisco district attorney, Harris established the United States’ first environmental justice unit. As California’s Attorney General, Harris sued the Obama administration to stop offshore fracking, sued several oil companies for environmental damage and set up an official investigation on how Exxon denied the public information about the climate risks of fossil fuels. The lawsuits led to the stopping of all new Pacific offshore fracking, even though large oil companies such as ExxonMobil have tried to get the U.S. Supreme Court to overturn the ban. In 2019 Harris promised to, if elected, prosecute oil and gas companies; this was not pursued as Vice President in the Biden administration but resurfaced as part of her presidential bid.

4. Electric Vehicles. Trump has repeatedly said he would roll back regulations to encourage electric vehicles, and at the Republican party convention, Trump promised to “end the electric vehicle mandate on day one”. At a fundraiser event, Trump promised major oil companies that if they donate one billion dollars to his campaign, he will stop all current incentives for electric vehicles.

As president, Trump tried to reduce fines for car companies that failed to meet fuel-economy standards but lost in court. He also tried but failed to block California and other states from introducing more stringent emissions and consumption standards, but managed to block steeper fines just before leaving office. Biden recently imposed an import tax on over 100 percent of Chinese electric cars; Trump claims this is insufficient and wants to also introduce a 100% tariff on Mexico-made EVs, which include many of the most popular EVs in the US.

Under Biden, the U.S. has set the targets of at least 30% zero-emission new vehicles by 2030, and 100% by 2040, targets that Harris will keep, but likely add incentives for low-income households. The National Zero-Emission Freight Corridor Strategy was developed by the administration’s Joint Office of Energy and Transportation with input from the Department of Energy (DOE), the Department of Transportation (DOT), and the Environmental Protection Agency (EPA). It lays the infrastructure out for increased numbers of zero-emission medium-duty and heavy-duty commercial vehicles.

5. International cooperation. The MIT Technology Review points out that international cooperation may be where Trump differs the most from the Democrats, with “wide-ranging pledges to weaken international institutions [and] inflame global trade wars.” Stating that “I was elected for Pittsburgh, not Paris”, Trump as president immediately withdrew the US from the UN Paris Agreement. One of Biden’s first decisions as president was to immediately rejoin. If elected, it is likely that Trump will withdraw again.

Under Biden, the US also ratified the Kigali Amendment on tackling climate-warming hydrofluorocarbons, which required Senate approval. Harris wants to further deepen the international climate cooperation. At COP28, speaking for the US, Harris said “the urgency of this moment is clear. The clock is no longer just ticking, it is banging. And we must make up for lost time.” She has pledged to “initiate the first-ever international coalition to manage the transition away from fossil fuel production” with major climate polluters – building on Biden’s major emitters summit which has so far failed to deliver substantial climate agreements between the US and China.

Grand total: Huge emissions gap

With Biden-Harris policies, the U.S. is approaching the emissions reduction required for the 2030 and 2050 goals; more is needed but can be achieved with fairly limited additional policy measures at federal and state levels.

Trump’s pledges to roll back and abolish IRA and other key components of the Biden administration’s climate policies would lead to 4bn tonnes of extra carbon dioxide equivalents by 2030 compared with a continued Biden/Harris administration, according to Carbon Brief’s calculations. Four billion tonnes of CO2e is equal to the total annual emissions of the EU and Japan, or the world’s 140 lowest-emitting countries, or double the emissions savings from wind, solar and other clean technologies around the world in the past five years. In terms of costs, it would lead to global climate damages worth more than 900 billion USD, using the US government valuations.

In fact, the difference is likely larger– since Harris as president would not only aim to keep what Biden has put in place but to add new climate initiatives, and Trump as second termer might well introduce additional measures to boost coal and oil, which are not part of the Carbon Brief Trump-scenario.

The Trump administration was not well prepared when they entered office, and several efforts to abolish climate rules and support coal, oil and gas were unsuccessful or could be reversed easily by the Biden-Harris administration. A second mandate for Trump would likely be more organized, with a plan to cancel regulations that curb emissions, support fossil fuel production and “destroy the EPA“.

The latter, however, would require a Republican control of the House and Senate – the president of the US is powerful but still, there are checks and balances in place.

The purpose of this text is not to endorse any of the candidates – it is for voters in the US to decide whom to have as president. But given how large the US emissions are, and how influential the country is, the choice of the US electorate will be crucial for all of us.

Mattias Goldmann