President Joe Biden urged world leaders Monday to act with urgency to prevent climate change from reaching catastrophic levels.

“This is the challenge of our collective lifetimes, the existential threat to human existence as we know it,” Biden said at the climate summit in Glasgow, Scotland. “And every day we delay, the cost of inaction increases. 

“So let this be the moment that we answer history's call here in Glasgow,” he said. “Let this be the start of a decade of transformative action that preserves our planet and raises the quality of life for people everywhere. We can do this. We just have to make a choice to do it.” 

Biden said climate change is “already ravaging the world.”

“It's not a hypothetical threat. It’s destroying people's lives and livelihoods,” he said, citing record heat, droughts, wildfires, flooding and powerful storms in the United States. 

After former President Donald Trump withdrew the U.S. from the Paris climate agreement, Biden is wading back into hands-on diplomacy with allies overseas this week. 

He said the country’s actions “will demonstrate to the world the United States is not only back at the table, but hopefully leading by the power of our example.”

“I know it hasn't been the case, and that's why my administration is working overtime to show that our climate commitment in action, not words,” Biden said.

The president touted the climate provisions in his Build Back Better plan, which is still being crafted in Congress. Among them would be investments in developing more clean energy, financial incentives for adding solar panels and wind turbines, and a goal to cut greenhouse gas emissions by more than a gigaton by 2030.

Biden said he’s focused on tackling the climate crisis while also creating jobs, including for auto workers, electricians, engineers and farmers.

“This is a moral imperative, but it's also an economic imperative,” the president said.

The Biden administration on Monday released its strategy for turning talk into reality in transforming the U.S. into an entirely clean energy nation by 2050. The long-term plan, filed in compliance with the Paris agreement, lays out a United States increasingly running on wind, solar and other clean energy, Americans zipping around in electric vehicles and on mass transit, state-of-the-art technology and wide open spaces carefully preserved to soak up carbon dioxide from the air.

And Biden said more initiatives will be announced in the coming days. 

The president also said the U.S. will try to do its part to help poor countries “be our partners in this effort.”

Biden is this week swinging the focus of his battle for fast, concerted action against global warming from the U.S. Congress, scolding rival China on climate and appealing to other leaders at a U.N. summit to commit to the kind of big climate measures that he is still working to nail down at home.

The summit is often billed as essential to putting the landmark 2015 Paris climate accord into action.

But Biden and his administration face obstacles in prodding the United States and other nations to act fast enough on climate, abroad as at home. In the runup to the summit, the administration has tried hard to temper expectations that two weeks of talks involving more than 100 world leaders will produce major breakthroughs on cutting climate-damaging emissions.

Rather than a quick fix, “Glasgow is the beginning of this decade race, if you will,” Biden's climate envoy, John Kerry, told reporters Sunday.

As the summit opens, the United States is still struggling to get some of the world's biggest climate polluters — China, Russia and India — to join the U.S. and its allies in stronger pledges to burn far less coal, gas and oil and to move to cleaner energy.

Biden did not call out those countries by name in his speech Monday, but said: “In age where this pandemic has made so painfully clear that no nation can wall itself off from borderless threats, we know that none of us can escape the worse that is yet to come if we fail to seize this moment.”

Major polluters including China and Russia have made clear they had no immediate intention of following the U.S. and its European and Asian allies to zero out all fossil fuel pollution by 2050. Scientists say massive, fast cuts in fossil fuel pollution are essential to having any hope of keeping global warming at or below the limits set in the Paris climate accord.

The world currently is on track for a level of warming that would melt much of the planet’s ice, raise global sea levels and greatly increase the likelihood and intensity of extreme weather, experts say.

The Biden administration has succeeded, over 10 months of diplomacy leading up to the Glasgow summit, in helping win significant new climate pledges from allies. That includes persuading many foreign governments to set more ambitious targets for emissions cuts, promoting a global pledge to cut emissions of a potent climate harm, methane, and the promise from leading economies to end funding for coal energy abroad.

European leaders make clear they are happy to see Biden and the U.S. back in the climate effort after Trump turned his back on the Paris accord and on allies in general. 

Neither Russian President Vladimir Putin nor Chinese President Xi Jinping is attending the Glasgow summit, although they are sending senior officials. Their refusals, and India’s, to move substantially faster to cut their reliance on coal and petroleum threaten to frustrate hopes of reaching the target cuts set in the Paris climate accord.

China under Xi has firmed up commitments to cut emissions but at a slower pace than the U.S. has encouraged.

U.S. national security adviser Jake Sullivan told reporters traveling with the president that climate change should not viewed as a rivalry between the U.S. and China, as China, the world’s second largest economy, could act on its own.

“They are a big country with a lot of resources and a lot of capabilities, and they are perfectly well capable of living up to their responsibilities,” Sullivan said. “Nothing about the nature of the relationship between the U.S. and China, structurally or otherwise, impedes or stands in the way of them doing their part.”

Biden comes to the international climate summit with the fate of his own climate package still uncertain in Congress. Objections from holdouts within Biden's own Democratic Party have compelled him to back away from one bill that would have prodded the United States' own move away from coal and natural gas and to cleaner energy for generating electricity.

Hundreds of billions of dollars of climate measures remain in Biden's package before Congress, however.

“The largest investment in the history of the world” on climate, Biden told reporters Sunday. “And it's gonna pass.”

The Associated Press contributed to this report.