07:47

Trump framed his decision to pull the US from the landmark Paris climate agreement as “a reassertion of America’s sovereignty”, adding he was “elected to represent the citizens of Pittsburgh, not Paris.”

He said the US could try to re-enter the deal under more favourable terms or work to establish “an entirely new transaction” – but indicated that it would hardly be of high priority. “If we can, great. If we can’t, that’s fine,” he said.

As my colleague David Smith reported earlier, the White House says America will follow the lengthy exit process outlined in the deal, meaning it will remain in the agreement (at least formally) for another three-and-a-half years – taking us right up to the next presidential election in November 2020.

Though the US will remain part of the United Nations Framework Convention on Climate Change, Trump declared: “As of today, the United States will cease all implementation of the non-binding Paris accord.”

That includes contributions to the UN Green Climate Fund (to help poorer countries to adapt to climate change and expand clean energy) and reporting on carbon data (though that is required in the US by domestic regulations anyway).

In a joint statement, the leaders of France, Germany and Italy responded to Trump’s decision “with regret”, but said the Paris agreement could not be renegotiated.

The question now becomes what efforts, if any, the US will adopt towards tackling climate change on its own terms – and whether the nearly 200 countries that remain in the deal will amend their own obligations.

The US is the world’s second-largest emitter of carbon, behind only China – which, along with India, was singled out by Trump as being favoured under the Paris deal. But both Beijing and New Delhi have reaffirmed their commitment to meeting their targets.

Trump is currently reviewing major US regulations on power plants and car rules that are aimed at reducing carbon emissions. The US Conference of Mayors, which strongly opposed his decision, said its members would continue efforts to reduce greenhouse gas emissions blamed for global warming at the city and state level.