Can the United States halve emissions by 2030? Biden says yes.

Declaring that the United States and other big economies must “get this done,” President Joe Biden opened a global climate summit Thursday aimed at getting world leaders to dig deeper on emissions cuts. The U.S. pledged to cut in half the amount of climate-wrecking coal and petroleum fumes it is pumping out.

“Meeting this moment is about more than preserving our planet,” Mr. 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.”

“The signs are unmistakable. The science is undeniable. The cost of inaction keeps mounting,” he added.

His new commitment to cut U.S. fossil fuel emissions up to 52% by 2030 marks a return by the U.S. to global climate efforts after four years of withdrawal under former President Donald Trump. Mr. Biden’s administration is sketching out a vision of a prosperous, clean-energy U.S. where factories churn out cutting-edge batteries for export, line workers re-lay an efficient national electrical grid, and crews cap abandoned oil and gas rigs and coal mines.

Japan, a heavy user of coal, announced its own new 46% emissions reduction target Thursday as the U.S. and its allies sought to build momentum through the summit.

The coronavirus pandemic compelled the summit to play out as a climate telethon-style livestream, limiting opportunities for spontaneous interaction and negotiation. The opening was rife with small technological glitches, including echoes and random beeps and voices.

But the U.S. summit also marshaled an impressive display of the world’s most powerful leaders speaking on the single cause of climate change.

Chinese President Xi Jinping, whose country is the world’s biggest emissions producer, followed by the U.S., spoke first among the other global figures. He made no reference to nonclimate disputes that had made it uncertain until Wednesday that he would even take part in the U.S. summit and said China would work with America in cutting emissions.

“To protect the environment is to protect productivity, and to boost the environment is to boost productivity. It’s as simple as that,” Mr. Xi said.

India, the world’s third-biggest emitter of fossil fuel fumes, has been pressing the U.S. and other wealthier nations to come through on billions of dollars they’ve 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 told participants. “We have taken many bold steps.”

The pandemic made gathering world leaders for the climate summit too risky. That didn’t keep the White House from sparing no effort on production quality. The president’s staff built a small set in the East Room that looked like it was ripped from a daytime talk show. Mr. Biden and Vice President Kamala Harris addressed the summit from separate lecterns before joining Secretary of State Anthony Blinken and White House climate envoy John Kerry at a horseshoe-shaped table set up around a giant potted plant to watch fellow leaders’ livestreamed speeches.

The format meant a cavalcade of short speeches by world leaders, some scripted, some apparently more impromptu. “This is not bunny-hugging,” British Prime Minister Boris Johnson said of the climate efforts. “This is about growth and jobs.”

The Biden administration’s pledge would require by far the most ambitious U.S. climate effort ever, nearly doubling the reductions that the Obama administration had committed to in the landmark 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 administration officials, in previewing the new target, disclosed aspirations and vignettes rather than specific plans, budget lines, or legislative proposals for getting there.

Mr. Biden and Vice President Kamala Harris opened the Earth Day summit from the White House East Room before world leaders, including those from China, Russia, India, Gulf oil states, European, and Asian allies and island and coastal nations already struggling against the effects of climate change. Pope Francis was also due to take part.

Mr. Biden planned to join a second session of the livestreamed summit later in the morning on financing poorer countries’ efforts to remake and protect their economies against global warming.

With the pledge from the U.S. and other emissions-cutting announcements 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 2.7 degrees Fahrenheit (1.5 degrees Celsius), the administration said.

As of 2019, the last year before the pandemic, the U.S. had reduced 13% of its greenhouse gases compared with 2005 levels, which is about halfway to the Obama administration goals of 26 to 28%, said climate scientist Niklas Hohne of Climate Action Tracker. That’s owing largely to market forces that have made solar, wind, and natural gas much cheaper.

Mr. Biden, a Democrat, campaigned partly on a pledge to confront climate change. He has sketched out some elements of his $2 trillion approach for transforming U.S. transportation systems and electrical grids in his campaign climate plan and in his infrastructure proposals for Congress.

His administration insists the transformation will mean millions of well-paying jobs. Republicans say the effort will throw oil, gas, and coal workers off the job. They call his infrastructure proposal too costly.

“The summit is not necessarily about everyone else bringing something new to the table – it’s really about the U.S. bringing their target to the world,” said Joanna Lewis, an expert in China energy and environment at Georgetown University.

Political divisions in America that were exposed by Mr. Trump’s presidency have left the nation weaker than it was at the 2015 Paris accord. Unable to guarantee that a different president in 2024 won’t undo Mr. Biden’s climate work, the Biden administration has argued that market forces – with a boost to get started – will soon make cleaner fuels and energy efficiency too cheap and consumer-friendly to trash.

Having the U.S., with its influence and status, back in the climate game is important, said Lauri Myllyvirta, lead analyst at the Centre for Research on Energy and Clean Air in Helsinki.

But hoping the world will forget about the last four years seems like wishful thinking, he said.

“There is too much of an impulse in the U.S. to just wish away Trump’s legacy and the fact that every election is now basically a coin toss between complete climate denial and whatever actions the Democrats can bring to the table,” he said.

This story was reported by The Associated Press. Ellen Knickmeyer reported from Oklahoma City. Associated Press writers Ashok Sharma in New Delhi, Joe McDonald in Beijing, Vladimir Isachenkov in Moscow, and Seth Borenstein, Matthew Daly, Alexandra Jaffe and Christina Larson in Washington contributed to this report.