The head of the International Energy Agency (IEA) has raised hopes of a positive outcome from the COP26 climate summit, saying that new national pledges to cut emissions have brought the world closer to meeting the aims of the 2015 Paris Agreement.

Following new analysis by the Paris-based agency, IEA executive director Fatih Birol said all new targets announced on top of those made previously could limit global warming to 1.8 degrees Celsius by the end of the century.

Delayed by 12 months because of the Covid-19 pandemic, COP26 is seeking to keep alive hopes agreed in Paris of limiting global warming to 1.5 degrees Celsius above pre-industrial levels.

“This is a landmark moment: It is the first time that governments have come forward with targets of sufficient ambition to hold global warming to below 2C,” Birol said.

However, the IEA cautioned that all commitments to cut greenhouse gas emissions would have to be met in full and on time.

Addressing the UN conference, Birol also said global carbon dioxide emissions are set to rebound this year to levels seen before the Covid-19 pandemic, which served as a reality check.

US climate envoy John Kerry said on Friday that progress was being made at the conference but also urged caution.

“I was surprised when I heard that,” Kerry said on Friday of the IEA forecast and other modelling during a press conference.

“Let me emphasise as strongly as I can — job not done. Job not done the day this ends. The first part of a job of codifying the urgency will hopefully be done. But that’s just the beginning. This is a 10-year, decade-long race,” he said.

Earlier Kerry said in a speech that there has been "genuine progress" at COP26.

"There is a greater sense of urgency at this COP, there is a greater sense of focus," he said.

Since mid-October, more countries have been raising their ambitions to cut emissions.

This includes India, where Prime Minister Narendra Modi this week strengthened the country’s 2030 targets and pledged to hit net-zero emissions by 2070.

Among other announcements at COP26 this week have been pledges to slow deforestation, reduce emissions of climate-harming greenhouse gas methane and to phase out coal use, plus initiatives to mobilise trillions of dollars of private finance to fund a global shift away from fossil fuels to cleaner energy.

Commenting on the IEA analysis, Juan Pablo Osornio of Greenpeace said: “Glasgow has seen some important announcements, but let’s not get too excited.

"The calculations being made are assuming countries like Australia and Saudi Arabia will reach net zero by 2050 simply because they’ve said they will.

"In reality they haven’t put in place funding or policies to actually get there. It’s like me saying I’m going to do a marathon some day, doing no training but still telling people I’m a marathon runner. It doesn’t stack up.

“Just as importantly, the goal we need to hit is 1.5C, not 2C. If we breach 1.5C then some countries will simply disappear from the map. So the takeaway from these calculations is that we need to see not just words but action, and a lot more of it.”

Early on Friday, thousands of young activists — including teenage Swedish campaigner Greta Thunberg — were gathering for a series of protests in Scotland's largest city Glasgow as the first week of the summit draws to a close.

Larger civil protests are planned for Saturday.