Saying the world's big economies "have to get this done,'' US President Joe Biden opened a global climate summit last night aimed at getting global leaders to dig deeper on emissions cuts.
The United States pledged to cut in half the amount of climate-wrecking coal and petroleum fumes it is pumping out.
President Xi Jinping, who spoke first among global leaders, reiterated China's pledge to peak carbon emissions before 2030 and achieve carbon neutrality before 2060.
Other leaders followed suit. With the pledges -including those from Japan, Canada, the European Union and the United Kingdom - countries representing more than half the world's economy will have now committed to cutting fossil fuel fumes enough to keep the Earth's climate from warming disastrously, more than 1.5 degrees Celsius, the US administration said.
"Meeting this moment is about more than preserving our planet,'' Biden said, speaking from a TV-style set for a virtual summit of 40 world leaders. "It's about providing a better future for all of us,'' he said, calling it a moment of peril but a moment of opportunity.''
He added: "The signs are unmistakable. The science is undeniable. The cost of inaction keeps mounting."
The Biden administration's commitment to cut US fossil fuel emissions up to 52 percent by 2030 marks a return by the United States to global climate efforts after four years of withdrawal under Donald Trump.
Japan, a heavy user of coal, announced its own new 46 percent emissions reduction target. Canada's Prime Minster Justin Trudeau also announced an emissions cut of 40 to 45 percent by 2030 below 2005 levels.
Xi emphasized that China is aiming to move from peak carbon to net zero in a short time period - just 30 years, or the span of one generation.
He said: "We must be committed to green development. To improve the environment is to boost productivity.'' Xi said developed countries, responsible for greater historical carbon emissions, should bear more responsibility for making changes at home and helping developing countries finance their transition to low-carbon economies.
"We must be committed to the principle to common but differentiated responsibilities," he added.
India, the world's third-biggest emitter of fossil fuel fumes, is pressing the United States and other wealthier nations to come through on billions of dollars they have promised to help poorer nations build alternatives to coal plants and energy-sucking power grids.
"We in India are doing our part,'' Prime Minister Narendra Modi said
The Biden administration's pledge would require by far the most ambitious US climate effort ever, nearly doubling the reductions that the Obama administration had committed to in the 2015 Paris climate accord.
The new urgency comes as scientists say that climate change caused by coal plants, car engines and other fossil fuel use is already worsening droughts, floods, hurricanes, wildfires and other disasters and that humans are running out of time to stave off most catastrophic extremes of global warming.
But US administration officials, in previewing the new target, disclosed aspirations and vignettes rather than specific plans, budget lines or legislative proposals for getting there.