THE US HAS officially returned to the Paris global climate accord as Joe Biden and other leaders declared the nation could not afford to sideline the growing climate crisis again.

“We can no longer delay or do the bare minimum to address climate change. This is a global existential crisis, and all of us will suffer if we fail,” the US president told European leaders at a Munich security conference by video.

“We’re back,” he added.

Officially, Donald Trump’s removal of the nation from the worldwide global climate pact stood for only 107 days, as part of his withdrawal from global allegiances in general and his often-stated but false view that global warming was a mistaken take by the world’s scientists.

The US return to the Paris agreement became official almost a month after Mr Biden told the United Nations that America wanted back in.

“A cry for survival comes from the planet itself,” he said in his inaugural address. “A cry that can’t be any more desperate or any more clear now.”

While Friday’s return is heavily symbolic, world leaders say they expect America to prove its seriousness after four years of being pretty much absent. They are especially anticipating an announcement in the coming months on its goal for cutting damaging emissions from burning coal and petroleum by 2030.

The Biden administration says it will settle on a tougher new target for the US emissions cuts by the time he hosts a planned Earth Day global summit for world leaders on April 22.

The president signed an executive order on his first day in office reversing the pullout ordered by Mr Trump. The Trump administration had announced its withdrawal from the Paris accord in 2019, but it did not become effective until November 4 2020, the day after the election, because of provisions in the agreement.

United Nations secretary-general Antonio Guterres said on Thursday that the official American re-entry “is itself very important”, as is Mr Biden’s announcement that the US will return to providing climate aid to poorer nations, as promised in 2009.

“It’s the political message that’s being sent,” said Christiana Figueres, the former United Nations climate chief. She was one of the leading forces in hammering out the mostly voluntary 2015 agreement in which nations set their own goals to reduce greenhouse gases.

One fear was that other nations would follow America in abandoning the climate fight, but none did, Ms Figueres said.

She added that the real issue was four years of climate inaction by the Trump administration, as American cities, states and businesses still worked to reduce heat-trapping carbon dioxide but without the federal government.

“From a political symbolism perspective, whether it’s 100 days or four years, it’s basically the same thing,” she said. “It’s not about how many days. It’s the political symbolism that the largest economy refuses to see the opportunity of addressing climate change.

“We’ve lost too much time.”