The goal of limiting global warming to 1.5C is in "intensive care" after the conclusion of the COP26 summit in Glasgow, Labour's Ed Miliband has told Sky News.
Speaking to Trevor Phillips on Sunday, the shadow business, energy and industrial strategy secretary said it is now "our job in the next 12 months to show that we can save it".
But appearing on the same programme, COP26 President Alok Sharma insisted the summit had "delivered" on the promise to keep 1.5C within reach.
"This is a historic agreement, we can be really proud of it, but this is just the start," he said.
The pair were speaking after world leaders reached the most significant climate change pact since the landmark 2015 Paris Agreement following a turbulent two weeks of fraught negotiations in Glasgow.
Its supporters say the pact will help ensure the 1.5C target is attainable, but many have pointed out it is far from perfect, with last-minute changes to fossil fuel wording proving highly controversial.
A highly contested fossil fuel statement made it through to the final pact, but was watered down at the last minute as India forced through a re-wording of "phase-out" to "phase down".
Major outcomes include:
Asked for the reasoning behind his downbeat assessment, Mr Miliband told Sky News: "The task of the world is to halve global emissions over the coming decade, that's by 2030.
"That's what the scientists tell us is necessary to keep 1.5 degrees alive and the truth about Glasgow, despite some progress, is that the world is only probably about 20% or 25% of the way to that goal.
"So, there is a chasm now between where we need to be in halving global emissions and all major countries have to step up and play their part in that, and where we are."
He said major countries have to "step up and play their part" to maintain the goal of limiting global warming to 1.5C, adding: "I think we are dragging our feet in a very problematic way."
Mr Miliband said he had "nothing but praise" for Mr Sharma and the work he did in Glasgow.
But he added that his work was "undermined" by some nations who refused to sign up to key pledges and climate finance.
Dieter Helm, Professor of Economics and Energy Policy, went further in his verdict on COP, telling Trevor Phillips on Sunday that 1.5C is "dead" and the "key players" were not at the table in Glasgow.
Asked what level of temperature hike we should realistically expect, Professor Helm said it is more likely to be between 1.8C and 2.4C.
"My guess is it's much closer to 2.4C," he said. "This is really serious, this is a dramatic change that will happen in this century and affect all of us."
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