Setting out how the Prime Minister’s recent net-zero policy delays would affect future emissions is “not appropriate”, Claire Coutinho has said.

The Secretary of State of Net Zero and Energy Security maintained that the Government is on track to meet its legal target of making the UK net zero by 2050, which means reducing emissions to the point at which they balance with those removed from the atmosphere through either nature or technology.

She also responded to claims that Rishi Sunak had scrapped policies that did not exist, such as taxes on meat eating and flying, by quoting suggestions from the Climate Change Committee, which advises the Government on how to reach net zero.

Writing to the Environmental Audit Committee (EAC) chairman, she added that the Prime Minister was being “fairer” and “more pragmatic” when he delayed the end of new petrol and diesel cars from 2030 to 2035, which aligns with other European countries.

Philip Dunne, EAC chairman, said Ms Coutinho failed to answer many of his questions and that a detailed response on the expected impact on future emissions would have helped his committee scrutinise the changes.

Ms Coutinho said: “With a constantly changing external environment covering economic, technological, and wider trends our plans will of course need to be revised over time.

“However, it is not appropriate, nor is it a requirement, to update and publish a revised version of the Carbon Budget Delivery Plan every time there is a change in economic data, a policy or wider factor.

“The Carbon Budget Delivery Plan, published in March, remains the most recent presentation of our detailed plans, with the vast majority of the near-200 quantified policies set out in the plan continuing unamended and remaining in place following the Prime Minister’s announcements.

“I will continue to keep under review our progress towards net zero and will take further action, if needed, to ensure we have sufficient proposals and policies in place to meet my legal duties.”

The CCC’s analysis of the changes, which included a 20% exemption for new gas boilers to be fitted after 2035, found they will make achieving the net zero target “considerably harder to achieve”.

Without commenting specifically on UK Government policy, the new Intergovernmental Panel of Climate Change chairman Jim Skea said putting off decarbonisation policies results in more warming in the long term as carbon dioxide stays in the atmosphere for centuries once emitted.

Mr Dunne said: “We welcome the Government’s stated ongoing commitment to meeting carbon budget and net zero targets.

“It is nevertheless disappointing that many of the committee’s specific questions have been left unanswered.

“A detailed response showing the impact on future emissions would have assisted our scrutiny of the revised timeframes for the phasing out of petrol and diesel vehicles and of fossil fuel boilers, and the potential impact of these changes on the emissions reductions required to meet net zero.

“We hope that further detail will be provided in the forthcoming Government response to the Climate Change Committee’s 2023 Progress Report on emissions reductions.”