The world needs the US to remain in the international climate process to avoid a “crippled” Paris agreement, the UN secretary general has warned, amid fears that Donald Trump would take the country out of the accord for a second time.

António Guterres said the landmark 2015 agreement to limit global heating would endure if the US withdrew once again, but compared the prospective departure to losing a limb or organ.

“The Paris agreement can survive, but people sometimes can lose important organs or lose the legs and survive. But we don’t want a crippled Paris agreement. We want a real Paris agreement,” the UN secretary general said.

If the Republican candidate wins, his administration could withdraw the US from the UN climate negotiating framework entirely, according to reports. If he does so, it could require Senate approval for the US to rejoin.

It raises the prospect of international cooperation on the climate falling apart by emboldening other countries to leave, which could result in catastrophic temperature rises globally and more extreme weather.

Speaking to the Guardian at the Cop16 biodiversity summit in Cali, Colombia, Guterres urged the US to stay and play its part in limiting global heating to 1.5C degrees above preindustrial levels.

“It’s very important that the United States remain in the Paris Agreement, and more than remain in the Paris agreement, that the United States adopts the kind of policies that are necessary to make the 1.5 degrees still a realistic objective,” he said.

The US became the first country in the world to formally withdraw from the Paris agreement in November 2020 after Trump announced it would leave in June 2017. Due to complicated rules about leaving the accord, there was a substantial delay between the decision and the formal departure.

Joe Biden rejoined the Paris agreement on the first day of his presidency in January 2021, with the US returning as an active participant in the UN climate process.

While the climate has been a peripheral issue in campaigning for the 2024 US presidential election, Trump – a frequent climate denier – has pledged to unleash a new wave of investment in fossil fuels, and cut support for electric cars and renewable energy.

Michael Mann, a climate scientist at the University of Pennsylvania, previously warned that a second Trump presidency would be a serious blow to US action on the climate.

“A second Trump presidency is game over for meaningful climate action this decade, and stabilising warming below 1.5C probably becomes impossible,” he said.

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