The United States is back to leading the world on fighting climate change and President Joe Biden will use a UN summit in Glasgow to energize partners, US officials said.

Special climate envoy John Kerry told reporters ahead of Biden's arrival on Monday at the COP26 summit that the aim is "to leave Glasgow having raised global ambition very significantly and to be more on track to keep a 1.5 degrees within reach".

Biden is set on Monday to address COP26, which is tasked with trying to maintain a global bid to restrict average temperature rises to 1.5C, preventing what scientists say will be an ever more destructive climate crisis.

He will also attend the summit on Tuesday before flying home.

Kerry highlighted a "very strong" US delegation at the two-week summit, including 10 cabinet secretaries and agency heads, and more than 50 members of Congress.

"This is a message you're going to see from the president over the next two days and from dozens of cabinet officials who will be in Glasgow over the next two weeks: the United States is back at the table, we're back, hoping to rally the world to tackle the climate crisis," climate adviser Gina McCarthy told reporters.

Pushing back against criticism that COP26 is getting off to a weak start, with only lukewarm action on that 1.5C goal from countries at a G20 summit in Rome at the weekend, Kerry said nations representing 65 percent of global GDP are committed to the effort.

Nine months ago, when Biden took office, "there were only two or three entities, very few, who were on track to try to hold 1.5 degrees," he said.

The other third of countries not fully on board are "the challenge coming out of Glasgow", he said. "Can those countries step up?"

John Kerry, United States Special Presidential Envoy for Climate, says the US will push for more 'global ambition' on climate goals
John Kerry, United States Special Presidential Envoy for Climate, says the US will push for more 'global ambition' on climate goals POOL / Patrick Semansky

He called agreement at the G20 in Rome on Sunday to end public financing for coal production abroad "a major breakthrough".

Kerry defended Biden's recent calls for increased oil production, saying this is a temporary response to energy shortages, and does not clash with broader climate goals.

Biden has been pushing the oil industry to counter rising energy prices for ordinary Americans by ramping up production. Similar shortages and price hikes have hit Europe.

"If he were asking them to boost their production over five years, I'd quit," Kerry said. "But he's not. He's asking them to boost production in this immediate moment."

Biden's climate pointman said that getting through the current energy crunch is important if governments are going to be able to carry public opinion in the transition to clean energy.

"If life is so miserable... and prices go up and other things happen, you're going to lose, I think it becomes more challenging to get the job done," he said.

"We're all trying to facilitate the transition. And as the transition cuts in, there won't be that need," he said. "So I just don't think it's inconsistent to say you're going to have a temporary capacity booster (to) keep the economy moving."