A much bigger push is needed from countries across the globe if the goal of keeping temperature rises to 1.5C is to be achieved, a leading expert has warned.

Peter Betts, who for years was the UK and EU lead negotiator in UN climate agreements, said it is “reasonably likely” that sufficient action will be taken to limit global temperatures rises to below 2C.

But with the Paris Agreement from 2015 having set out to limit global warming “preferably to 1.5C” compared with pre-industrial levels, he said action from counties such as China and India is critical.

Mr Betts was speaking halfway through the Cop26 summit, which is currently taking place in Glasgow.

He travelled to Scotland for the huge UN event, but is now isolating after testing positive for Covid-19, although he insisted there have been “relatively few cases” so far.

Speaking about progress made so far, Mr Betts told BBC Scotland’s Sunday Show: “This is not going to be the meeting that solves the climate problem in a single bite.

“The truth is we have made significant progress on tackling climate change and we will have made more at this meeting, but it is just nothing like enough, so we are going to need to accelerate.”

Climate campaigners marched through Glasgow at the halfway point of the Cop26 summit (Jane Barlow/PA)

Mr Betts spoke out the day after tens of thousands of demonstrators marched through Glasgow, demanding more action on the environment.

He said that one of the “most important” things for the Cop26 summit is for countries to increase action to reduce emissions by 2030.

And while he said some countries had made pledges to do this ahead of the talks starting, others had not.

“Who we didn’t hear from was China – they didn’t significantly tweak their ambition and that is a concern,” he said.

These increased targets could help “close the gap” towards achieving 1.5C by about 20% to 25%, the expert added, saying this is “significant” but “just not enough”.

Cop26 has also seen commitments made to reduce deforestation, decrease methane production and move away from burning coal.

Mr Betts said: “If you aggregate all of that stuff together… maybe we might be on track for something like 2C.

“But the big proviso is countries need to implement what they have signed up to. That is where we need to focus, real pressure to make countries deliver what they have said they are going to do.”

He continued: “The decisions that are most important will be the decisions that are made in Beijing, in Delhi, in the capitals of South East Asia, so we have to find arguments that resonate with them.

“We are not going to solve the problem without their taking significant action. That is not to put the blame on them, that is just the reality of the arithmetic of where the tonnes are coming from.”

The adviser said there is “growing momentum” for tackling climate change, adding: “When you look at the targets in the developed world they imply very, very stringent policy over the coming years.

“I think it is reasonably likely we can get below 2C if we maintain the momentum –  1.5C is much harder and we’re going to need a much bigger push to get there.”