Rishi Sunak has said he cannot put a “precise figure” on exactly how much it will cost for the UK to transition to a net zero economy.

The Chancellor was asked on The Andrew Marr Show on BBC One on Sunday what the cost would be, as he insisted that “very good progress” was being made towards commitments to limit global warming.

But despite Government advisory body the Climate Change Committee and former chancellor Philip Hammond estimating it would take £1.4 trillion, Mr Sunak said: “It’s very difficult to put a single figure on something that’s going to happen over the 30 years, three decades, during which lots of things are going to change, not least the cost of many of these technologies.

The Andrew Marr show
Chancellor of the Exchequer Rishi Sunak appearing on The Andrew Marr Show (Jeff Overs/BBC)

“So you know, I can’t reduce it to one single figure.”

He said the public should be reassured progress was being made but when asked whether the figure was simply “too scary” to include in a recent Government report on reaching net zero, Mr Sunak said: “No, again I think that something that happens over 30 years, the transition of an entire economy, I think it is tricky to put a precise figure on it.”

Mr Sunak was unable to say whether the upcoming Cop26 summit in Glasgow would be a failure if international agreement was not reached on sticking to targets to limit global heating to 1.5C.

He told the BBC: “No, I think Glasgow will be a success, particularly on the finance side, which I’m responsible for.”

But when pushed on whether the world had to stick to the 1.5C commitment, he said: “We are making enormous progress.

“All I’d say – if you want a very brisk answer I’d say this – when we took over the Cop presidency just 30% of the world’s economies had net-zero targets in place. That is already up to 80%. We’ve played a part in making that happen and there’s more to come over the next couple of weeks. I feel confident that we’ll have a good summit.”

Asked a third time, The Chancellor said: “We’re making very good progress on it.”

It comes as Labour’s Rachel Reeves said she wanted to be known as a “green chancellor”.

The party’s shadow chancellor told The Andrew Marr Show: “I believe that the only responsible chancellor at the moment is a green chancellor, to stop the costs building up for future generations to pay.

“The moral imperative of tackling the climate emergency and the opportunity to create those high-skill, high-productivity jobs in this country.

“You know, the Government’s saying we can improve productivity by getting shortages on the shelves. No, I say we improve our productivity by investing in the skills and the jobs of the future, and that more than anything means investing in carbon capture and storage and hydrogen, in gigafactories to build the electric vehicles of the future.

The Andrew Marr show
Shadow chancellor of the exchequer Rachel Reeves arrives at BBC Broadcasting House, London, to appear on the BBC1 current affairs programme, The Andrew Marr show. (Aaron Chown/PA)

“That’s the way to boost our skills and our productivity.”

She said Labour had pledged to invest £28 billion a year of Government spending through the course of this decade into reaching net zero.

But when asked whether it was fair for Britain to stump up the cost and be seen to be “going first and doing it for ourselves” if countries like China and Russia would not meet the targets, she said: “But we’re not going first and doing it for ourselves, because our own plans don’t get us to net zero by 2050.

“But there are big opportunities by being a first mover in this because we can ensure that the jobs of the future come to our shores and that we have opportunities to export those skills and services round the world.

“So that’s why I say the only responsible chancellor in these times is a green chancellor, and that is what I would intend to be.”