But Boris Johnson says the achievements of the Glasgow summit are “tinged with disappointment”.
The Glasgow climate deal is a “game-changing agreement” which sounds “the death knell for coal power”, Boris Johnson says.
Although countries only agreed to “phase down” rather than “phase out” coal, the prime minister said this was a fantastic achievement.
The change was made after a late intervention by China and India.
But it remains the first time plans to reduce coal have been mentioned in such a climate deal.
The agreement was reached after the two-week Glasgow COP26 summit went into overtime on Saturday.
Speaking at a Downing Street news conference, Mr Johnson said that despite the achievements of the summit, his reaction was “tinged with disappointment”.
He said there had been a high level of ambition demanded by those at the summit – especially from countries where climate change was already “a matter of life and death”. And “while many of us were willing to go there, that wasn’t true of everybody”.
But the UK could not “force sovereign nations to do what they do not wish to do”.
“It’s ultimately their decision to make and they must stand by it.”
Mr Johnson also said he thought the watered-down language on coal did not “make that much of a difference”, adding that the direction of travel was “pretty much the same and that’s never been said before”.
Speaking alongside the PM, COP26 president Alok Sharma, revealed that at one point during the final negotiations, he had feared the agreement was in jeopardy.
“There was an hour where really we weren’t going to get a deal,” he said.
Mr Sharma, who fought back tears as he closed the summit following the late intervention, said: “I can tell you there was one really tense hour where I did feel the weight of the world on my shoulders… this deal was absolutely in jeopardy. We got it over the line.”
He added that “China and India will have to explain themselves” to climate-vulnerable nations.