The outgoing chair of the UK Government’s statutory climate advisers has been left “extremely disappointed and increasingly concerned” that neither the Tories nor Labour are prioritising a move to net zero.

Tory peer Lord Deben, who has stepped down as chairman of the Climate Change Committee (CCC), has warned that both his Conservative colleagues in Westminster and Keir Starmer’s ambition o become the next government, are not taking the climate crisis seriously enough.

Lord Deben was asked on Times Radio, whether he was “surprised” by the lack of enthusiasm for the climate crisis by both major parties at Westminster, giving the scale of the challenge to tackle it.

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In response, Lord Deben said: “Well, I don't think I'm surprised, I'm just extremely disappointed and increasingly concerned because it seems to me that it is the priority.

“There is nothing more important than securing the world for our children.

“And indeed, I may be quite old now, but it's securing it for me, because this is changing so fast that we are going to make the world an impossible place for us to live in the way in which we have lived up to now.”

Lord Deben stressed that “we have to act very quickly”, but insisted “it can be done”.

He added: “It's still within our reach as the Climate Change Committee said to the Prime Minister, you can get back on course if you move now and don't wait for the next election.”

Lord Deben said the Prime Minister has “recommitted himself to the money that is going to the developing countries” so they “can go straight to renewables”.

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He added: “The last thing we want is for them to go through the oil and gas period.

“That is a very major recommitment. But there's a lot more to do.”

Reports had suggested that Rishi Sunak was ready to drop a £11.6bn pledged to help developing nations tackle the climate crisis.

Lord Deben also issued a warning to his Conservative colleagues at Westminster concerned about immigration that a failure to tackle the climate crisis will simply exacerbate the issue.

Estimates suggest that as many as 1.2 billion people could be displaced globally by 2050 due to the climate crisis and natural disasters.

Lord Deben said: “I would say to those people who are most concerned about migration, you have not seen anything yet.

“When these countries are too hot to live in, people will move not to better their lives, but to have a life of their own.

“So unless we act very urgently, we're going to have a world which is absolutely destroyed by climate change.”

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The warning came as Labour shadow chancellor criticised tactics used by climate campaigners, insisting she has “got no time” for Just Stop Oil.

She added that the tactics of disputing sporting events was “a bit pathetic and quite tedious”.

She added: “If they want to tackle climate change, engage in the policy answers, but they are not building support for their cause, they are doing the exact opposite.

“So it is counter-productive and it is rude frankly.

“People paid to go to Wimbledon, it may be the one time in their life that they get to Wimbledon, they don’t want to be disrupted by a load of protesters.”