He warned that global temperature rises were already inevitable, but called on his fellow leaders to commit to major changes to curb further warming.
Four areas needed tackling – “coal, cars, cash and trees”, he said.
Countries must take responsibility for “the destruction we are inflicting, not just upon our planet but ourselves”.”It’s time for humanity to grow up,” he added ahead of the UK hosting the COP26 summit in Glasgow.
The prime minister also said it was time to listen to the warnings of scientists. “Look at Covid if you want an example of gloomy scientists being proved right.”
Setting the tone for November’s meeting, he said countries must make “substantial changes” by the end of the decade if the world is to stave off further temperature rises.
“I passionately believe that we can do it by making commitments in four areas – coal, cars, cash and trees,” he said. Johnson praised China’s President Xi Jinping for his recent pledge to stop building new coal-fire energy plants abroad.