The new edition of the duel for the American presidency between Joe Biden and Donald Trump could be a close race. Another Trump presidency is possible. And even if he doesn't win, his rhetoric, particularly on environmental issues, will set the Republican agenda. The president can still have great influence over US environmental and climate policy, even with a divided legislature.

Trump's personal distaste for climate policy

Trump has a long-standing personal antipathy toward climate change and the tools to combat it. This has barely changed since he left office. Last year, for example, he falsely claimed that wind turbines were killing whales and that sea level rise would be a small fraction of what forecasts actually show. And he said, contrary to the facts, that the US military under Biden wanted to use electric tanks and energy-saving fighter jets.

Attack on the IRA investment program

In a possible second term, Trump would try to undo the achievements of his predecessor. On the one hand, Biden managed to sign two important climate laws: the bipartisan infrastructure bill and the bill to reduce inflation, the well-known “Inflation Reduction Act” (IRA). Republicans want to partially reverse this law: in April 2023 they already promoted a proposal in the House of Representatives that would eliminate tax advantages for renewable energies and even introduce higher taxes for them.

The money for these laws has already been allocated. Congressional action would be needed to halt their investments in clean energy, electric vehicles and efficient appliances. Many red states also benefit from these investments, so Trump may be less inclined to block them entirely.

Conservative think tank “Project 2025”

But Trump could reverse many of Biden's measures. Republicans have learned from his chaotic first term. They want to start developing a coherent plan in case of a new electoral victory. The Heritage Foundation, a right-wing think tank, worked with former Trump administration officials to create an agenda for this: Project 2025.

Consequently, a Trump administration would limit the powers of federal agencies like the Environmental Protection Agency (EPA) to give more authority to the states. The Energy Department would focus more on fossil fuel development. The president can authorize oil and gas exports and mining on public lands. Trump is likely to push this funding even further.

Symbolism: Withdrawal again from the Paris Agreement

Trump could also declare that the United States would once again withdraw from the Paris climate agreement. It may be a symbolic gesture and will take years to be officially completed. But Trump loves symbols, ceremonies and speaking in front of cameras.

But even with federal agencies, Trump's power is not absolute. One of the problems of his first presidency was that many of his policies were questioned by environmental activists and Democratic-led states. Many of his cuts to environmental regulations were blocked and never implemented. And Trump's opposition has also learned from his first term. While state and local leadership groups like We Are Still In paused their activities under the Biden administration, activist organizations like the Sunrise Movement have continued to mobilize to give Trump the benefit of the doubt.

Attack on the legal basis of climate policy

This time, however, Trump would have courts at his disposal that are more favorable to him. During his tenure, he appointed 174 of 677 federal district judges, 54 of 179 appellate judges, and three of nine Supreme Court justices. These judges are appointed for life and have continued to make policy decisions in Trump's absence, blocking new environmental regulations on water and vehicle emissions, for example.

One of the conservatives' long-standing goals is to repeal the EPA's 2009 endangerment ruling, which is the main piece of legislation requiring the government to regulate greenhouse gases. Although the courts have so far rejected challenges to this decision, conservative groups have not given up. Under Trump, they might one day make their case before a judge who agrees with them.

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Better selection of personnel.

Trump has also learned the hard way what human resources means: that the people he chooses to run his administration determine what he can accomplish. Trump's first choice to lead the EPA was Scott Pruitt, who praised Trump but also racked up a long list of scandals. His successor, Andrew Wheeler, held back but was still able to advance Trump's deregulation agenda. Trump would probably be more careful in choosing his staff without attracting too much unnecessary attention.

However, one of the crucial variables for a second Trump term remains Trump himself, known for throwing out plans, making decisions on a whim and acting on what the last person he spoke to told him. Therefore, there will be fierce competition for his audience.

But there is already a dynamic of decarbonization in the US economy. Coal-fired power continues to decline, electric cars are becoming more popular, and renewable energy remains the cheapest source of new electricity, even in Republican-governed states. Trump can slow down efforts to limit climate change, but he won't be able to stop them.