VIDEO: 'No more blah blah blah,' says Greta Thunberg in Glasgow as COP26 opens

British Prime Minister Boris Johnson on Monday opened the historic COP26 climate summit by warning world leaders that they faced a damning verdict from future generations unless they act decisively.

Swedish teenage climate activist Greta Thunberg said that world leaders "have kept going on for too long" during a protest outside the COP26 climate summit in Glasgow.

Thunberg said, “We say: no more 'blah blah blah', no more exploitation of people and nature and the planet. No more exploitation, no more 'blah blah blah'. No more whatever the f*** they're doing inside there! We are sick and tired of it and we are going to make the change, whether they like it or not. They have kept going on for too long, and we are not going to let them get away anymore. We are not."

Boris said, “The anger and the impatience of the world will be uncontainable, unless we make this COP26 in Glasgow the moment when we get real about climate change, and we can get real on coal, cars, cash and trees."

Boris echoed 18-year-old climate campaigner Thunberg — who is in Glasgow with thousands of other protesters — in urging the summit against indulging in "blah blah blah."

If the leaders "fluff our lines or miss our cue", generations as-yet unborn "will not forgive us", the prime minister said.

"They will know that Glasgow was the historic turning point when history failed to turn.

"They will judge us with bitterness and with a resentment that eclipses any of the climate activists of today -- and they will be right," he said.