The PM insisted his changes announced on Wednesday - delaying a ban on non-electric vehicle sales and the phase-out of old boilers - were necessary to maintain public support for the 2050 net zero target during a cost-of-living crisis.
“We’re absolutely not slowing down efforts to combat climate change. I passionately do want to make sure that our country gets to net zero,” he told the Today programme on Radio 4.
But new analysis by the Energy and Climate Intelligence Unit (ECIU), a think tank, said the changes would add £20 billion to household energy bills over the next decade, by failing to mandate better insulation and leaving the UK reliant on expensive imported gas.
“The decisions yesterday will do nothing to help the cost-of-living crisis. In fact they’re going to make it worse,” Simon Cran-McGreehin, head of analysis at the ECIU, told the Standard.
“There’s a lot of commentary around that this is the starting gun on an election campaign. But a majority of people do want action on climate action,” he added.
Labour’s shadow energy security secretary Ed Miliband said he relished the opportunity to go “toe to toe” with the Tories on net zero during next year’s election campaign.
Sir Keir Starmer’s party said it would maintain the original 2030 deadline to end sales of diesel and petrol vehicles, which the PM has now extended to 2035.
Labour also said the dilution of eco-pledges would cost the public more in the long term and accused Mr Sunak of “selling out” the opportunity for a green jobs boom - a criticism echoed by senior Tories such as former PM Boris Johnson.
Former Levelling Up secretary Simon Clarke tweeted: “Nobody serious in politics was talking about banning flying, taxing meat etc.”
Lord Zac Goldsmith, who resigned from Mr Sunak’s government in June with a fiery attack on his climate record, said: “This is cynical beyond belief. The PM is pretending to halt frightening proposals that simply do not exist.”
But the PM said he wanted to have an “honest conversation” with the public about the costs of net zero, claiming some of the proposals had been floated by the CCC and the seven bins were mentioned in environmental legislation.
“No, I reject that entirely,” Mr Sunak said when told the proposals had never existed as policy.
“These are all things that have been raised by very credible people about ways to meet our net zero obligations.”
But CCC chief executive Chris Stark denied that he had ever pushed for a meat tax, and echoed the ECIU in arguing that delay on climate action would cost households and businesses more in the long run.
The scrapped proposals were “straw men”, Mr Stark said, adding: “He seemed to be cancelling a set of policies that the government hadn’t announced.”
But Business Secretary Kemi Badenoch rejected criticism from the auto and energy industries, and said critics such as the wealthy Lord Goldsmith were out of touch.
She told LBC: “Zac Goldsmith is someone who cares very much about the environment. He’s a friend of mine. But the fact is, he has way more money than pretty much everyone in the UK.
“We are world leading. We’ve cut our emissions further and faster than pretty much anyone else,” Ms Badenoch added. “But we need to make sure that we continue to do this in a way that people can afford.”