The world is at “one minute to midnight”, having run down the clock on waiting to combat climate change, Prime Minister Boris Johnson has said.
He was speaking as world leaders gather for the landmark COP26 climate change conference in Glasgow.
Speaking to the BBC, Mr Johnson said leaders needed to move from “aspiration to action” to slow global warming.
He added the summit was a “critical” moment for him, and said an ambitious outcome was still “in the balance”.
For the first time, Mr Johnson also confirmed he did not want to see a controversial proposed coal mine in Cumbria go ahead.
“I’m not in favour of more coal,” said the prime minister. “But it is not a decision for me, it is a decision for the planning authorities.”
The government has been criticised for not stopping the mine project going ahead.
This is the strongest statement the prime minister has yet made on the subject – and could help negotiations, because persuading nations to phase out coal is one of the central goals the UK government has set for the crucial UN conference.
The UK is hosting the summit amid mounting concern among scientists that countries are not doing enough to limit the emissions of greenhouse gases, which have caused average global temperatures to rise.
The 2015 Paris climate conference called for average temperatures to rise by well below 2C, and preferably only 1.5C, when compared to pre-industrial averages.
Mr Johnson promised to add £1bn to the money the government has earmarked over the next four years to help developing countries.