Just three months after the landmark summit, there is a danger that the vital pledges made will “wither on the vine”, the cabinet minister will say in a major speech.
Cop26 saw the world’s wealthiest countries fail to make commitments to keep global heating to 1.5°C – above which scientists warn runaway climate change is inevitable.
The level of CO2-cutting pledges made will result in the planet warming by up to 2.4°C, even if they are followed up with practical policies and legislation.
The Glasgow summit ended with Mr Sharma in tears – and critics warned the crisis was simply “kicked down the road”, to Cop27 in Egypt at the end of this year.
In a speech at Chatham House, the Cop26 president, will say: “There is no doubt that the commitments we secured at Cop26 were historic. Yet at the moment they are just words on a page.
“And unless we honour the promises made, to turn the commitments in the Glasgow Climate Pact into action, they will wither on the vine.
“We will have mitigated no risks. Seized no opportunities. We will have fractured the trust built between nations. And 1.5 degrees will slip from our grasp.”