UK Prime Minister Boris Johnson says a climate summit of world leaders in 40 days’ time will be the turning point for humanity.

He was delivering a speech to the United Nations yesterday.

He warned that global temperature rises were already inevitable, but called on his fellow leaders to commit to major changes to curb further warming.

He said four areas needed tackling, coal, cars, cash, and trees.

The prime minister also said it was time to listen to the warnings of scientists.

Mr. Johnson praised China’s President Xi Jinping for his recent pledge to stop building new coal-fire energy plants abroad.

But he called on the country – which produces 28% of global greenhouse gas emissions – to go further and end its domestic use of coal, saying the UK was proof that it could be done.