If nations honor their latest pledges to reduce greenhouse gas emissions, the rise in average global temperatures by the end of the century could be held to 1.8 degrees Celsius, a new analysis by International Energy Agency says.

That's short of a goal set by world leaders six years ago, but far less than the trajectory that the planet is on today, says the agency, part of the Organization for Economic Cooperation and Development.

The IEA's new analysis includes promises made just this week at the COP26 U.N. climate conference in Glasgow, Scotland. Many countries at the ongoing conference have pledged to eliminate carbon emissions by 2050 and dozens have said they will cut releases of methane — an even more potent greenhouse gas — by nearly a third.

An independent group called Climate Action Tracker estimates that under current policies, the planet is likely to warm by between 2.7 and 3.1 degrees Celsius (4.8 to 5.6 degrees Fahrenheit), compared to pre-industrial times. That's higher than the aim of 1.5 degrees C (2.7 degrees F) rise agreed to in the 2015 Paris Climate Agreement and seen as necessary to avoid the most catastrophic consequences of climate change.

Ahead of the summit in Scotland, known as the Conference of Parties, or COP26, the International Energy Agency had forecast that if countries were able to fulfill their pledges on climate action made up to that point, average global temperatures by the end of the century would rise by 2.1 degrees Celsius (3.8 Fahrenheit) from preindustrial times.

"Since mid-October, however, more countries have been raising their ambitions," the IEA report says. "Indian Prime Minister Narendra Modi strengthened the country's 2030 targets, and pledged to hit net zero emissions by 2070. Several other large economies have also announced pledges to reach net zero emissions."

The analysis also factored in commitments from China — which in recent years has surpassed the U.S. as the world's largest polluter — as well as the commitment by more than 100 countries to cut their emissions of methane by 30%.

In a tweet, IEA Executive Director Fatih Birol said the results signal a "big step forward," but cautioned that much more is needed.

Carrying out the climate pledges is key

The announcement was met with substantial skepticism, though, because for this optimistic scenario to occur, countries would actually have to carry out their pledges. Many of the world's biggest polluters have failed to honor their past pledges, and carrying out these promises will be a huge challenge.

Several big countries, such as Australia and Russia, have yet to say how they will go about cutting their emissions and the Biden administration's proposals to reduce U.S. output still need approval from a deeply divided Congress.

John Kerry, the U.S. presidential special envoy for climate, said he was "surprised" by the IEA estimate. He said it's encouraging, but shows how important it will be for countries to fulfill their promises. "Implementation, that is the key," he said at a news conference.

The World Resources Institute, a nonprofit climate policy think tank, cautions that holding temperature rise to 1.8 C is possible if everything falls into place. But it also suggested that a number of the net-zero carbon emission targets recently pledged lack credibility.

Meanwhile, a separate analysis by Australian scientists which has not yet been peer reviewed, predicts warming of 1.9 degrees C (3.4 degrees Fahrenheit) if current commitments are kept.

"We are now in a slightly more positive outlook for the future," said University of Melbourne climate scientist Malte Meinshausen, according to The Associated Press. He said that the more optimistic assessment comes mostly as a result of new long-term pledges made by India and China.

"It's still a long way away from 1.5 degrees," Meinshausen acknowledged, adding, "We know that some of the ecosystems are going to suffer."

"It is just scraping below 2 degrees. So therefore there's a lot more to be done," he said.

Dan Charles reported from Glasgow, Scotland; Scott Neuman is based in Washington, D.C.