HUMZA Yousaf has accused the Prime Minister of an “abdication of leadership on a colossal scale” following his U-turn over introducing a raft of key net zero policies.

The First Minister, who last week attended New York Climate Week, said the world needs “climate leaders, not climate deniers” and pledged that Scotland will be “on the right side of history”.

In a speech from Downing Street on Wednesday, Rishi Sunak announced a pushing back of the deadline for phasing out gas boilers and petrol and diesel cars, as well as scrapping energy efficiency targets for landlords.

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The Tory leader claimed he was still committed to the target of ­reaching net zero by 2050, but the move prompted a huge backlash – ­including from critics within his own party.

Yesterday a world-leading economist also condemned the rollback as “reprehensible”, saying it caused ­uncertainty for a clean energy ­transition for business and that the “moral status” of the UK had been weakened in international negotiations on environmental protections.

Yousaf told the Sunday ­National: “It was an honour to represent ­Scotland on the global stage and join world leaders and heads of local and national governments at events in New York to mark Climate Week and the UN General Assembly.

“The fact that the Scottish ­Government was invited to attend the UN Climate Ambition Summit at the ­personal invitation of UN ­Secretary-General, Antonio Guterres, is a ­testament to the leadership ­Scotland has shown on climate issues such as loss and damage.

“We are facing a climate catastrophe, and it’s clear that even more bold and ambitious action is needed, and with greater urgency. This is not just a moral imperative, it’s an ­economic one too and an ­opportunity for Scotland to unleash its full renewables potential.

“We are already starting to see the devastating, fatal, effects of a warming planet in the form of floods, ­extreme weather events and wildfires across the world, including on our own continent. The world needs ­climate leaders, not climate deniers.”

He went on: “The Prime ­Minister’s rollback on green measures to ­appease a very narrow wing of his party is an abdication of leadership on a colossal scale. It takes the UK out of the global consensus that is demanding more action to tackle the climate catastrophe, not less.

“Scotland will be on the right side of history.

“I am committed to continuing to work in collaboration with other ­nations to drive forward bold action to tackle the climate crisis, and ­ensure that we leave a sustainable planet for our children, grandchildren and ­future generations to come.”

Professor Sir Partha Dasgupta (below), an expert on the economics of biodiversity, attacked Sunak’s decisions as he delivered the second annual James Mirrlees Lecture at Wigtown Book Festival yesterday.

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Asked his views on Sunak’s statement on changes in green policies he said: “I want to point to two of the less obvious reasons as to why it’s so reprehensible. One is that in the world of manufacturing, the world of business and in the world of ­production, you need lead time.

“It was really interesting that the earliest criticisms came from producers saying: ‘How can we plan the transition to clean energy when we have to billions of ­dollars of investment if the entire time horizon shifts?’.

“I think that’s well worth ­bearing in mind because this is not a left-right issue.”

He added: “The second reason why it’s reprehensible relates to ­biodiversity and how we can negotiate and ­persuade poor countries to better manage their natural capital, for ­example, to protect the rainforest.

“They’ll be saying: ‘Well, in Europe as soon as you feel the pinch, the first cut is to Mother Nature’. It means that our moral status and our ­position in negotiations is weakened.”

Indeed, last week, the Scottish ­Government said it was “urgently” assessing Sunak’s watering down of climate pledges, after being given no notice of the plans.

But the SNP have said it means Scotland will have to delay banning new petrol and diesel cars.