The decision would place the United States alongside Iran, Libya and Yemen as the only countries in the world outside the 2015 pact, in which governments agreed to limit global warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels to avoid the worst impacts of climate change.

The announcement, in a document from the White House, reflects Trump’s skepticism about global warming, which he has called a hoax, and fits in with his broader agenda to unfetter U.S. oil and gas drillers from regulation so they can maximize output.

United Nations Secretary-General Antonio Guterres is confident that U.S. cities, states and businesses "will continue to demonstrate vision and leadership by working for the low-carbon, resilient economic growth that will create quality jobs," said associate U.N. spokesperson Florencia Soto Nino, in a written statement.

"It is crucial that the United States remains a leader on environmental issues," she said. "The collective efforts under the Paris Agreement have made a difference but we need to go much further and faster together."

The United States is already the world’s top producer of oil and natural gas thanks to a years-long drilling boom in Texas, New Mexico and elsewhere fueled by fracking technology and strong global prices since Russia’s invasion of Ukraine.

SECOND U.S. WITHDRAWAL

Trump also withdrew the U.S. from the Paris deal during his first term in office, though the process took years and was immediately reversed by the Biden presidency in 2021. The withdrawal this time around is likely to take less time – as little as a year - because Trump will not be bound by the deal’s initial three-year commitment.

This time could also be more damaging to global climate efforts, said Paul Watkinson, a former climate negotiator and senior policy advisor for France.

The U.S. is currently the world's second-biggest greenhouse gas emitter behind China and its departure undermines global ambition to slash those emissions.

"It will be harder this time because we are in the thick of implementation, up against real choices," Watkinson said.

The world is now on pace for global warming of more than 3 C by the end of the century, according to a recent United Nations report, a level scientists warn would trigger cascading impacts such as sea level rise, heat waves, and devastating storms.

Nations have already been struggling to make steep cuts to emissions required to lower the projected temperature increase, as wars, political tensions and tight government budgets push climate change down the list of priorities.

Trump’s approach cuts a stark contrast to that of former President Joe Biden, who wanted the United States to lead global climate efforts and sought to encourage a transition away from oil and gas using subsidies and regulations.

Trump has said he intends to unwind those subsidies and regulations to shore up the nation’s budget and grow the economy, but has said he can do that while ensuring clean air and water in the United States.

Li Shuo, an expert in climate diplomacy at the Asia Society Policy Institute, said the U.S. withdrawal risks undermining the United States' ability to compete with China in clean energy markets such as solar power and electric vehicles.

"China stands to win, and the U.S. risks lagging further behind," he said.