U.S. climate envoy John Kerry is tempering expectations for a U.N. climate summit sometimes billed as make-or-break for the Earth's future, conceding next month's talks likely will end with nations still short of the target of cuts in coal and petroleum emissions that are needed to stave off increasingly devastating levels of global warming.

But in an interview with The Associated Press, Kerry also credited efforts by the United States, European Union, Japan and other allies ahead of next month's climate negotiations in Glasgow, Scotland with getting the world much closer to the scale of big, fast fossil fuel cuts needed. He expressed hope enough nations would join in over the next couple of years. "By the time Glasgow's over, we're going to know who is doing their fair share, and who isn't," he said.

Kerry also spoke of the impact if the U.S. Congress - under a slim Democratic majority - fails to pass legislation for significant action on climate by the United States itself, as the Biden administration aims to regain leadership on climate action. "It would be like President Trump pulling out of the Paris agreement, again," Kerry said.

Kerry spoke to the AP Wednesday in a conference room down the hall from his office at the State Department, its upper corridors still eerily shy of people in the coronavirus pandemic. Kerry's comments came after nine months of intensive climate diplomacy by plane, phone and computer screen aimed at nailing down the most global commitments of action on climate possible ahead of the U.N. climate summit, which opens Oct. 31 in Scotland.

Kerry plans final stops in Mexico, and in Saudi Arabia, where he expected new, last-minute climate pledges ahead of the summit, before settling in Glasgow for two weeks of talks.

Kerry's efforts abroad, along with President Joe Biden's multibillion-dollar promises of legislation and support for cleaner-burning energy at home, come after President Donald Trump pulled the United States out of the Paris climate accord.

Kerry rejected a suggestion he was seeking to lower expectations for the summit, which became a deadline - but not a final one, leaders have begun stressing - for countries to announce how hard they will work to switch their economies from polluting to cleaner-burning. Kerry and others early on billed the Glasgow summit as "the last, best chance" to drum up momentum for the emissions cuts, investment in renewable energy, and aid to less-wealthy countries to allow them to switch from dirty-burning coal and petroleum in time to limit warming to 2.7 degrees Fahrenheit (1.5 degrees Celsius).

The world has already warmed nearly 2 degrees Fahrenheit (1.1 degrees Celsius) since nations of the world set that target in Paris in 2015. Scientists warn the damage is irreversible and headed to catastrophic levels absent major cuts in emissions.

When it comes to closing the divide between cuts promised by countries and the cuts needed, "We will hopefully be moving very close to that...though there will be a gap and...we've got to be honest about the gap, and we have to use the gap as further motivation to continue to accelerate as fast as we can," Kerry said Wednesday.

In the meantime, money pouring into developing cleaner technology such as battery storage will be spurring the advances that will make it easier for laggard countries to catch up, he contended.

A senior U.N. official separately briefing reporters Wednesday also spoke less stirringly than international leaders often have previously of the expected accomplishments of Glasgow. Speaking on condition of anonymity to discuss the matter, the official left open the door that some work on getting to the international goal of a 45% cut in emissions by 2030 may not be done by end of the Glasgow climate negotiations. The official stressed that the Paris accord allows countries to submit stronger pledges at any time.

Critically, Kerry's repeated trips to China and diplomatic efforts by other countries have failed so far to win public promises of faster emissions cuts from that key climate player. China's enthusiasm for coal-fired power plants help make it the world's biggest current climate polluter by far. China under President Xi Jinping shows no interest in being seen as following the U.S. lead on climate or anything else.

Kerry declined to single out China by name as one reason why Glasgow might not be as big a success as it could have been - although surprise announcements by China remain a possibility.

"It would be wonderful if everybody came and everybody hit the 1.5 degrees mark now," he said. "That would be terrific. But some countries just don't have the energy mix yet that allows them to do that."

For Biden at home, it's the lawmaker mix that's the problem. Holdouts from the president's own party so far are blocking the administration's multibillion-dollar climate legislation of the kind needed to make good on U.S. climate pledges of support for clean energy.

Asked how the administration's troubles delivering on its own climate promises affect his work rallying climate action abroad, Kerry said, "Well, it hurts."

"I'm not going to pretend it's the best way to send the best message. I mean, we need to do these things," he said.

Kerry added he was optimistic Congress would step up. "I don't know what shape it'll take...or which piece of legislation, it'll be in, but I believe we're going to act responsibly" at home, he said.

From the Associated Press