The presidential election between Vice President Kamala Harris and former President Donald Trump presents the American public with a clear choice on the future direction of US climate policy. To date, climate has not come up as a campaign topic. However, the issue looms large because the choice is so stark: a Harris presidency promises continuity with Biden’s approach, while a Trump administration would likely adopt a more oppositional and even hostile stance on climate issues.

While this election has potentially significant ramifications for climate policy at the federal level, the evolution of US climate politics over the past decade offers reasons for guarded optimism.

Harris: choose continuity

A Harris administration would seek to build upon the Biden administration’s climate agenda, further embedding climate considerations into the US policy landscape.

A key issue for the success of US climate policy is permitting reform, which will be essential for accelerating the deployment of clean energy across the country. These reforms are vital for achieving the US’s 2030 goals, such as reducing greenhouse gas emissions by 50-52 per cent compared to 2005 levels, and have garnered bipartisan support. If not passed by Congress in 2024, they will likely be a top priority for both the White House and Congress in January 2025.

Additionally, as president, Harris could pursue options including carbon border adjustment mechanisms (CBAMs), “polluter pays” initiatives, and policies to strengthen environmental justice. The emphasis on economic growth and job creation, a hallmark of Biden’s climate policy (“When I think about climate, I think about jobs”), would likely be a cornerstone of Harris’s approach as well. For climate policy to succeed in the US, it must demonstrate tangible benefits for American workers and consumers.

On the international front, Harris could aim to bolster US commitments to global climate policy, an area neglected by the 2022 Inflation Reduction Act (IRA) for lack of political support, and one that stands to benefit from new ideas and policy approaches. Like any president, Harris’s ability to advance federal climate policy will depend on the composition of the next Congress, where partisanship, fiscal challenges, and budgetary constraints could impede progress.

Trump might withdraw (once again) from the Paris Climate Agreement or even exit the United Nations Framework Convention on Climate Change.

Trump: Go your own way

A second Trump administration would present a difficult yet familiar scenario for US allies and climate advocates. Trump’s hostility toward climate policy would likely manifest in attempts to roll back climate regulations implemented by Biden, repeal or scale back the tax credits in the IRA, and seek budget cuts to agencies central to climate policy, such as the Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA). Trump and his supporters view these entities as part of the “administrative state”, which they consider detrimental to the country.

On the international stage, Trump might withdraw (once again) from the Paris Climate Agreement or even exit the United Nations Framework Convention on Climate Change, the broader framework for the Paris Agreement. Such actions would signal that the US is no longer a reliable partner in global climate efforts, raising urgent questions about the future of international climate cooperation and the US’s role on the world stage.

Resisting assumptions: reasons for optimism

It is crucial for climate advocates to prepare for either scenario. Supporters of climate action should avoid making simplistic assumptions about the future direction of US climate policy – a President Harris will not ensure unfettered climate action, and a President Trump will not spell the end of the energy transition. Stepping back from partisan politics and sensational headlines, it is evident that the US climate policy landscape is evolving. There are several reasons for this:

Growing interest in climate action on the political Right: According to Pew Research, 54 per cent of Republicans support US participation in international climate efforts. The Congressional Conservative Climate Caucus, which now has 81 members (up from 64 when it launched in 2021), reflects this growing interest. These “eco-right” conservatives recognise the importance of addressing climate change in ways consistent with conservative principles. Their perspectives will be central to shaping US climate policy moving forward, under either a Harris or Trump administration.

Impact of the IRA: As of April 2024, 206 billion dollars in domestic clean energy manufacturing investments have been announced. According to the Rhodium Group, nearly half a trillion dollars (493 billion) has been invested in clean technologies since the enactment of the IRA, compared to 288 billion dollars in the two years preceding the law. An estimated 70 per cent of these investments are going into Republican states, creating jobs and economic opportunities. While this does not guarantee their political support, it does make Americans more familiar with the tangible benefits of climate policy.

US states leading on climate policy: Climate policy doesn’t only happen on the federal level; US states are stepping up to the plate. California aims for net-zero emissions and 100 per cent clean energy by 2045; Illinois has set a target of 100 per cent clean energy by 2050; Minnesota, under Governor Tim Walz (currently Harris’s candidate for  Vice-President), aims for 100 per cent carbon-free electricity by 2040; and Texas has surpassed California in installed solar power. These states and others will continue to drive climate policy despite federal turbulence.

Private sector embracing the energy transition: Between the second quarter of 2022 and the second quarter of 2024, investment in clean manufacturing accounted for more than half of the growth in total private investment in structures, equipment, and durable consumer goods nationwide. A US trucking company executive recently remarked, “Our company is going to invest in clean energy not for political reasons, but because it makes so much economic sense… it’s just cheaper.” This growing recognition within the private sector reinforces the momentum behind climate action in the US.

In short, US climate policy has gained a certain momentum that makes it difficult for any one person or movement to reverse.

US allies across the Atlantic can help protect the integrity of global climate policy and ensure that efforts to address climate change do not falter.

What can US friends and allies do?

Regardless of the next administration, the role of US allies and supporters of climate action will be critical. Countries committed to climate action can help sustain momentum in the face of potential US retrenchment. By championing the benefits of clean energy, building relationships with states, engaging with the private sector, and connecting with pro-climate conservatives, US allies across the Atlantic can help protect the integrity of global climate policy and ensure that efforts to address climate change do not falter in the event of a US volte-face.

Navigating uncertainty

This election stands as a pivotal moment in history, with the potential to shape the future of global climate action and determine the planet’s environmental trajectory for decades to come. The outcome of the 2024 US presidential election will have profound implications for both domestic and global climate policy. The direction chosen by US voters in 2024 will significantly impact the pace and effectiveness of these efforts.

However, US climate policy in 2024 exists in a much different context than in 2015-2016. The fate of US climate action no longer rests solely on the actions of a single administration but on the collective efforts of actors across American society to address the climate challenge.