Scientists have called on Theresa May to use the "special relationship" with the United States to press Donald Trump to acknowledge and act on climate change.
Leading climate scientists are among 100 academics who have written to the Prime Minister warning damage inflicted by Mr Trump's administration on US-funded climate change research would have an impact around the world, including in the UK.
The UK experts raised concerns over statements by the president-elect that he does not fully accept the scientific evidence of climate change, while nominees for key posts in his administration have rejected the evidence for global warming risks.
They also warned of reports that the incoming administration may severely weaken climate change research by federal organisations in the US, such as Nasa.
"This would diminish the provision of robust and rigorous evidence that is used by policy-makers and researchers around the world, including in the United Kingdom," they wrote.
Mr Trump has previously described climate change as a hoax invented by the Chinese to undermine US manufacturing and pledged to withdraw from the world's first comprehensive treaty to tackle greenhouse gases, the Paris Agreement.
In the letter to the PM, the experts said the UK should be prepared to "respond decisively" to the situation, as the country has been at the forefront of international climate change research and evidence-based policy-making for more than 30 years.
They urged Mrs May to "press President-elect Trump and his administration to acknowledge the scientific evidence about the risks of climate change, to continue to support international action to counter climate change, including the Paris Agreement, and to maintain support for world class research and data-gathering on climate change in the United States".
The scientists said they were ready to stand by their counterparts in the US to "resist any political attempts to prevent, hamper or interfere with vital research on climate change".
And they said the UK could have a great opportunity to work alongside the US in strengthening the evidence base on climate change, supporting the development of new technologies and leading international co-operation on the issue.