President-elect Donald Trump has made no secret of his views on climate change. During his first presidency from 2017 to 2021, he repeatedly expressed doubts about it being caused by human behavior, calling it a "hoax." Out on the campaign trail for a second term, he called it "one of the great scams of all time."

So, now that's he's been elected for a second term, what's in store for the climate during a new Trump era?

Global climate efforts at stake

"Trump's victory presents a real obstacle in the global fight against climate change," said Alice Hill, senior fellow at independent think tank, the Council on Foreign Relations. "Under President Trump's leadership, the United States will almost certainly step back from global and domestic efforts to reduce greenhouse gas emissions, increasing fossil fuel production."

2024 is virtually certain to be the warmest year on record and the first year above 1.5 degrees Celsius (2.7 degrees Fahrenheit) warming, according to a new report by the EU's Copernicus Climate Change Service. And scientists have long been sounding the alarm about the need to cut our planet-heating emissions in half by 2030 to avoid climate catastrophe.

Achieving that goal means working together. But experts warn that Trump's "America First" policies don't go hand-in-hand with global collaboration on climate action — even though the US is currently the world's second-largest emitter of greenhouse gases after China, and the biggest historical emitter. 

'Drill, baby, drill!'

Ahead of the election, Trump pledged to expand domestic fossil fuel production, focus more on oil and gas and spend less on clean energy.

"Donald Trump and his supporters clearly have a view that oil and gas is really central to America's global strength and that shouldn't be toyed with," said Clarence Edwards, executive director of E3G's Washington office, a nonprofit think tank that works on the intersection of climate and geopolitics.

During his first term,Trump's administration promoted increased drilling for oil and natural gas, including in protected areas like Alaska's Arctic National Wildlife Refuge, and championed the construction of pipelines like Keystone XL and Dakota Access. 

Even before the election, Trump had hinted that he would continue this trend if he won. But Edwards said that doesn't mean renewables will go away completely, it just means the incoming administration will focus more on hydrocarbons.

What does a second Trump term mean for the Paris Agreement?

Trump's victory comes just days before the UN climate conference, COP29, gets underway in Azerbaijan. During his first term in office, the president-elect pulled the US out of the Paris Agreement, which is a commitment to keep global temperature rise to well below 2 degrees Celsius above pre-industrial levels.

Trump's withdrawal from the treaty was a major point of contention at the time, and though the US rejoined under current President Joe Biden, Edwards believes the incoming president is likely to make the same move again. 

"It would be a wrong signal to send. It's important that the US live up to its agreements and be a committed global player," he said, adding that if Trump were to withdraw from the Paris Agreement again, it would raise questions about other international climate commitments.

Implications for environmental policies

During his first term, Trump rolled back dozens of Environmental Protection Agency regulations, loosened restrictions on carbon emissions from power plants and vehicles and weakened rules governing pollutants like methane. 

Barry Rabe, professor of environmental policy at the University of Michigan, predicts a renewed dilution of environmental rules.

"There are a number of things that Mr. Trump has said during this campaign about trying to push out the boundaries of executive or presidential power beyond traditional norms, like impounding funds, which we normally don't give the president power to do," he said.

Rabe also anticipates a return to more lax regulations that would likely mean the US cannot meet its 2030 climate targets.

"The US is going to fall considerably short of that target for carbon dioxide, but also methane and most other greenhouse gases," he said. 

What will become of the IRA?

While some fear the landmark Inflation Reduction Act (IRA), a climate bill signed by Biden that invested hundreds of billions of dollars into renewable energy deployment, electric car production and battery manufacturing, may be at stake under Trump, Edwards doesn't believe that to be so.

"It has been wildly successful in driving clean energy manufacturing and jobs across the country, especially in so-called red [Republican — Editor's note] states, which are receiving about 70% of the investments from the Inflation Reduction Act, so I do think that there will be an effort to maybe not repeal the entire IRA, but tweak it in sections," he said. 

And Rabe agrees. "Realistically, it would take an act of Congress to fully repeal the IRA." 

He added that on IRA provisions, "it would not be surprising to see a Donald Trump return to the Oval Office trying to actually stop spending or slow down spending on congressionally authorized pots of funding that he didn't like."

Environmental impact of Trump's Project 2025

Ahead of the election, a group of conservative organizations and think tanks developed a controversial document called Project 2025, a series of policy proposals and strategic recommendations for a second Trump presidency. 

The document promotes the continued development of the American fossil fuel industry, advocating for more oil, natural gas and coal production as well as fewer restrictions around extraction and building new fossil fuel infrastructure.

One report found that if Trump passes the energy and environmental policies outlined in the document, it could add four billion tons to the country's emissions by 2030.

That would be equivalent to almost another whole year's worth of US greenhouse gases spewed into the atmosphere. 

It would make it impossible for the US to meet its goal of cutting emissions in half by 2030, which scientists have said is vital to avert disastrous climate change. 

Not all gloom and doom

"However, this outcome does not spell the be-all and end-all for climate action in the United States," said Hill of the Council on Foreign Relations, pointing to the power of state-level action and progress already made in some cases. "Local political and regulatory intervention will be critical in the fight for a healthier planet — with or without support from the Trump administration." 

Edwards said it's vital to get people working together and continue to make progress.

"It sounds fanciful, but I think it's important to really have a bipartisan dialogue about what we need to do around climate," he said. "We're not going to have a sustainable long-term climate policy in the United States unless we get bipartisan consensus." 

Louise Osborne contributed to this report.

Edited by: Tamsin Walker