The chances of limiting global heating to 1.5C above pre-industrial levels are already slim, and Trump's antipathy to climate action would have a major impact on the US, which is the world's second biggest emitter of greenhouse gases and biggest oil and gas exporter, said Patricia Espinosa, who served as the UN's top official on the climate from 2016 to 2022.

"I worry [about the potential election of Trump] because it would have very strong consequences, if we see a regression regarding climate policies in the US," Espinosa said.
Although Trump's policy plans are not clear, conversations with his circle have created a worrying picture that could include the cancellation of Joe Biden's groundbreaking climate legislation, withdrawal from the Paris agreement and a push for more drilling for oil and gas.

Espinosa said: "We are not yet aligned to 1.5C. That's the reality. So if we see a situation where we would see regression on those efforts, then [the likelihood of staying within 1.5C] is very limited. It would certainly be a much bigger risk.

"We could see a slowdown, an even bigger slowdown [in action to reduce emissions], which would unfortunately probably take us to an even more terrible scenario, unless we see strong leadership coming from other places, [such as] Europe."

She said other countries must continue with climate action even if the US were to renege on its goals under Trump, but the absence of the US would be a significant blow. "What happens in the US has a very big impact in so many places around the world," she said.