Rishi Sunak’s decision to water down environmental policies has “set us back” on reaching net zero, the outgoing head of the Government’s climate watchdog has said.

Chris Stark told the BBC other countries now regarded the UK as “less ambitious on climate” after the Prime Minister gave a speech last year delaying or scrapping some policies meant to cut carbon emissions.

He added: “In the speech itself, he talked about the need to reappraise lots of the steps that take us to net zero. My honest answer to that is I think it set us back.”

Climate Change Committee chief to step down
Chris Stark is stepping down as chief executive of the Climate Change Committee at the end of April (Climate Change Committee via PA)

Mr Stark, who is due to step down as chief executive of the Climate Change Committee at the end of April, said Mr Sunak had not made net zero “as much of a priority as some of his predecessors” and it would be “extremely difficult to recover” the UK’s international reputation on climate action.

The Government remains formally committed to reaching net zero by 2050, but has delayed a ban on the sale of new petrol and diesel vehicles and weakened targets on home insulation and phasing out gas boilers.

In his speech in October, Mr Sunak said the changes were a more “pragmatic, proportionate, and realistic approach to meeting net zero” that reduced the burden on the public.

A Government spokesperson said: “Our record on net zero speaks for itself – we are the first major economy to halve greenhouse gas emissions since 1990 and have set into law one of the most ambitious 2035 climate change targets of any major economy.

“But we need to reach our net zero goals in a sustainable way so we have taken action to protect our energy security, ease the burdens on hard-working people and provide transparency about the choices involved so that we bring people with us in meeting our climate targets.”

In his interview with the BBC, Mr Stark said the Scottish Government’s decision to remove some of its own climate change targets provided a “salutary lesson”.

He said: “Political ambition is exactly what we need in climate change, but that was a bridge too far. There wasn’t a credible path to that target.”

As well as setting an overall target for reaching net zero by 2045 – five years earlier than the UK Government’s target – the Scottish Government had aimed to reduce emissions by 75% by 2030.

Mairi McAllen, Scotland’s Net Zero Secretary, confirmed on Thursday that the 2030 target had been abandoned as it was now “out of reach”.

Asked whether the Scottish Government had originally set ambitious targets for “political reasons”, Mr Stark agreed, adding: “We gave them advice on the sort of steps you would need to take to hit that target, but they weren’t politically palatable.”

On Friday, Ms McAllen said she was “not embarrassed” by the decision, emphasising that the overall goal of reaching net zero by 2045 remained and Scotland had already reduced emissions to almost 50% of the level recorded in 1990.

Mr Stark also told the BBC Labour should be more “bold” on climate change, with Sir Keir Starmer talking about the subject more.

He added: “You look out your window and you see we’ve had, you know, the wettest 18 months ever in this country, we’ve got the hottest year on record in the last 12 months.

“I think people around the world know climate change is happening, but there is definitely a fear of talking about it in British politics at the moment.”