Boris Johnson will say that “it will be too late for our children” to take action if leaders do not “get serious about climate change today”, when he makes a speech in Glasgow later today,
His stark warnings come as UN experts said that the last seven years have been the hottest on record, with climate-related destructive weather extremes having been seen this year.
In the intervening period since 2015, when countries secured the Paris Agreement to curb temperature rises to 1.5C or well below 2C to avoid the worst impacts of climate change, have been the hottest in records dating back to 1850.
Meanwhile, the Met Office has also said that the global temperature has - on average - exceeded 1c above pre-industrial age levels for the last two decades.
The period from 2002 - 21 recorded an average of 1.01c above pre-industrial times.
This is the first time that a 20-year-long period has been at that level since records began, and highlights the importance of international pledges to keep global warming below 1.5c
When he addresses leaders in Scotland, it is thought that Mr Johnson will say: “Humanity has long since run down the clock on climate change.
“It’s one minute to midnight and we need to act now.
“If we don’t get serious about climate change today, it will be too late for our children to do so tomorrow.”
He is also expected to say: “We have to move from talk and debate and discussion to concerted, real-world action on coal, cars, cash and trees.
“Not more hopes and targets and aspirations, valuable though they are, but clear commitments and concrete timetables for change.
“We need to get real about climate change and the world needs to know when that’s going to happen.”
More than 120 leaders are set to attend the world leaders summit where countries are under pressure to increase action in the next decade to curb dangerous warming and to deliver financial support for poorer countries that are least responsible for and most vulnerable to climate change.
Cop26 President Alok Sharma drove home a similar message when he spoke at the summit’s opening, telling delegates that the 12-day long event is the “last best” chance to keep the 1.5c ambitions alive.
“The rapidly-changing climate is sounding an alarm to the world to step up on adaptation, to address loss and damage, and to act now to keep 1.5 alive,” Mr Sharma said.
“We know that this Cop, Cop26, is our last, best hope to keep 1.5C in reach.”
He added: “We know our shared planet is changing for the worse and we can only address that together through this international system.”
Concluding his speech, Mr Sharma said: “If we act now, and we act together, we can protect our precious planet.
“So, let’s come together in these two weeks and ensure that where Paris promised, Glasgow delivers.”
The conference, which officially began yesterday, will also hear from figures including Prince Charles the Prince of Wales and Sir David Attenborough, as well as UN secretary general Antonio Guterres before it closes.
UN representative Patricia Espinosa has already told those attending that the challenge to tackle climate change is “beyond the scope, scale and speed of anything humanity has accomplished in the past”,
“Let Glasgow be the starting point of this new era – this new age of resilience – and let Cop26 mark its beginning,” she said.