Five ways a Trump presidency would be disastrous for the climate

The climate crisis may appear peripheral in the US presidential election but a victory for Donald Trump will, more than any other issue, have profound consequences for people around a rapidly heating world, experts have warned.

During his push for the White House, Trump has called climate change a “hoax” and “one of the great scams of all time” while vowing to delete spending on clean energy, abolish “insane” incentives for Americans to drive electric cars, scrap various environmental rules and unleash a “drill, baby, drill” wave of new oil and gas.

Such an agenda would be carried out over a four year-period that nearly rounds out a crucial decade in which scientists say the US, and the world, must slash planet-heating pollution in half to avoid disastrous climate breakdown.

Already, major emitters such as the US are lagging badly in commitments to cut emissions enough to avoid a 1.5C (2.7F) rise in global temperature above the pre-industrial era. With just over 1C in average warming so far, the world already has record heatwaves , a rash of wildfires , turbocharged hurricanes , plunging wildlife losses, a crumbling and increasingly green Antarctica, the looming collapse of the oceans and a faltering ability of forests, plants and soil to absorb carbon.

Related: What's at stake in the US election? The climate for the next million years | Bill McKibben

“We’ve got to get off fossil fuels as quickly as possible,” said Michael Mann, a climate scientist at the University of Pennsylvania. “It’s hard to see that happening in the event of a Trump victory.” Mann added that “a second Trump presidency is game over for meaningful climate action this decade, and stabilizing warming below 1.5C probably becomes impossible”.

So what would a Trump election triumph mean for the environment?

A dangerous and uncertain future

Amid the frenetic bombast of politics, it is easy to overlook the long legacies of electoral decisions. Action or inaction on the climate crisis in the span of just the next few years will help decide the tolerability of the climate for generations not yet born.

“We have now brought the planet into climatic conditions never witnessed by us or our prehistoric relatives,” as a recent paper authored by more than a dozen scientists warned. “We are on the brink of an irreversible climate disaster. This is a global emergency beyond any doubt.”

There is enough momentum behind the record growth of clean energy that it won’t be utterly derailed by a Trump presidency. But a Trump White House would still have a tangible impact, adding, by some estimates, several billion tonnes of heat-trapping gases that wouldn’t otherwise be in the atmosphere, gumming up the international response, subjecting more people to flood or fire or toxic air. It would help prod societies ever closer to the brink of an unlivable climate.

Kamala Harris has declined to lay out much of a vision on how she would tackle the climate crisis, and barely even mentions it on the campaign trail, but to some experts the stakes are compellingly clear. “With Kamala Harris, there’s a good chance we can avert truly catastrophic global climate impacts,” said Mann. “With Trump there is not. It’s night and day.”

Climate denialism would return to the Oval Office

A new Trump administration would bring a jarring rhetorical shift. Unlike almost every other world leader – such as Joe Biden , who has called the climate crisis an “existential threat” – Trump dismisses and even mocks the threat of global heating.

In recent weeks, the former president has said that climate change is “one of the great scams of all time, people aren’t buying it any more” and has falsely claimed the planet “has actually got a bit cooler recently”, that rising sea levels will create “more oceanfront property”, that wind energy is “bullshit, it’s horrible” and even that cows and windows will be banned by Democrats if he loses.

Trump has coupled this with demands for unfettered oil and gas production in all corners of the US and has actively courted industry executives for donations. “He wholeheartedly believes we should produce our own energy sources here in the US, there’s no grey area there,” said Thomas Pyle, president of American Energy Alliance, a free market group.

“President Trump marches to the beat of his own drum, he’s his own man. He is instinctively in the right place on these issues – he wants to see more energy production across the board and less government intervention in the cars we drive and the stoves we have.”

Related: What’s at stake for the climate if Trump wins? – podcast

Others see signs a second Trump presidency will be even more extreme on climate than the first iteration. “The style, the indifference to empirical evidence and the bold sweeping gestures are familiar,” said Barry Rabe, an energy policy expert at the University of Michigan. “But this sequel will be an aggressive, revenge-based repudiation of anyone who has challenged him in the past.”

Clean energy policies unpicked

A primary target for a new Trump administration would be the landmark climate bill signed by Biden that is pushing hundreds of billions of dollars to renewable energy deployment, electric car production and battery manufacturing.

Trump has promised to “terminate Kamala Harris’s green new scam and rescind all of the unspent funds”. In its place, oil and gas production, already at all-time highs , will be boosted by opening up Alaska’s Arctic to drilling and ending a pause on liquified natural gas exports to “cut the cost of energy in half within the first 12 months of taking office”.

Achieving a full repeal of the climate bill, named the Inflation Reduction Act, will hinge upon the composition of Congress. Even if Republicans won both the House of Representatives and the US Senate, as well as the White House, there would still be some pushback from conservative members who have seen a disproportionate torrent of clean energy investment and jobs flow to their districts.

“I don’t think we will see the Inflation Reduction Act fully overturned, it will be more surgical than that,” said Kelly Sims Gallagher, an environmental policy expert at Tufts University. “The US is already a top oil and gas producer but what would likely change is the companion investment in low-carbon energy. That seems less likely under a Trump administration.”

Without Congress, Trump will still be able to slow the rollout of spending and demolish regulatory actions taken under Biden, such as rules cutting pollution from coal-fired power plants, cars and trucks and efforts to shield disadvantaged communities from pollution. Penalties for leaking methane, a potent greenhouse gas that is rising at a galloping pace , will also be targeted following complaints from some of Trump’s top oil industry donors.

In his first term, Trump squashed more than 100 environmental rules but the courts halted much of his agenda. This time, a more ruthlessly efficient and prepared operation is expected , backed by a conservative-aligned judicial system, including the supreme court itself. “He will work quickly, I think, to dismantle the Biden approach,” said Pyle.

A purge of science

A far more ideological slant on science and expertise is likely to emerge should Trump win office, with Project 2025 , the conservative manifesto authored by many former Trump officials, calling for civil servants to be replaced by loyal political operatives.

Mentions of the climate crisis were sidelined or erased during Trump’s last term and a repeat is widely expected. Climate considerations for new government projects will likely be ditched, states will get less help to prepare for and recover from disasters and public weather forecasts will be privatized, Project 2025 has suggested.

Scientists, who remember research being buried and Trump publicly changing an official hurricane forecast map with a Sharpie pen during his first term, fear a reprise. “The United States will become an unsafe place for scientists, intellectuals and anyone who doesn’t fit” with the Republican agenda, Mann said.

Trump has said that “nuclear warming”, which seems to be a reference to nuclear war, is a greater threat than global warming and that while he likes the idea of clean water and air “at the same time you can’t give up your country, you can’t say you can’t have jobs any more”.

When disasters, driven by a warming world, do hit the US, Trump has signaled he will withhold federal aid to places that didn’t vote for him in return for unrelated concessions. The former president did this multiple times when in office, his ex-staffers have revealed , and recently threatened California with a repeat.

International relations shaken

As president, Trump took several months to decide to remove the US from the Paris climate agreement. “This time I think he would do that on the very first day, likely with a lot of dramatic flourish,” said Rabe.

With the US, again, out of the international climate effort, American aid to developing countries vulnerable to floods, droughts and other disasters would also be slashed, along with cooperation with nations on other initiatives, such as cutting methane and curbing deforestation.

Trump’s fixation upon tariffs, meanwhile, would probably stymie the import of clean energy components to the US. Retaliatory tariffs, including penalties for carbon-intensive goods, could follow. “I’d expect an aggressive ‘America first’ role which will be a very interesting moment for the European Union with their carbon border adjustments – how will they respond to a more bullying America?” Rabe said.

Related: ‘In a word, horrific’: Trump’s extreme anti-environment blueprint

As in Trump’s first term, US disengagement would raise fears that other countries will also withdraw from the climate fight, causing global heating to spin out of control. China, the world’s leading emitter, has retained a level of cooperation with the Biden administration on climate despite an overall strained relationship with the US, but this faces rupture if Trump wins.

“It’s safe to assume there won’t be any climate engagement between Beijing and Washington,” said Li Shuo, a China climate policy specialist at the Asia Society Policy Institute. “It would be negative for the US and for the world. The US still looms large on the global stage, so I’d expect Trump would sow greater resistance to a climate agenda in China. We will see that commitment to climate start to crumble.”