The U.S. Is Skipping This Year’s Climate Summit. For Many, That’s OK.

For the first time since countries began gathering 30 years ago to wrestle with global warming, the United States will not send any top government officials to the annual United Nations climate summit, which kicks off on Thursday in Belém, Brazil.

And that is just fine with those who see the Trump administration’s hostility toward anything related to climate change as a menace to international cooperation on global warming.

“I normally subscribe to the idea that we should always be at the table,” said Senator Brian Schatz, Democrat of Hawaii. “But if we’re going to be at the table and turn it over, then I think it’s best if we don’t show up.”

Not only has the Trump administration abandoned America’s promises to the rest of the world that it would control the greenhouse gas pollution that is dangerously heating the planet, it has been pressuring other countries to similarly back away from efforts to fight climate change.

The administration has teamed up with other oil-producing nations to oppose a global plastics treaty and to compel Europe to abandon a climate law. It has also torpedoed the first-ever global fee on carbon pollution in the shipping industry. President Trump lectured world leaders at the United Nations in September, telling them if they did not “get away from this green scam, your country is going to fail.”

Laurence Tubiana, who has served as France’s climate negotiator and now runs the European Climate Foundation, a research organization, said she has been shocked by the “level of aggressiveness” with which Mr. Trump and his cabinet secretaries have opposed Europe’s climate goals.

That has prompted some to say discussions could go more smoothly in Brazil without the United States, even though U.S. delegates have played a central role in designing climate agreements over three decades and the country arguably bears special responsibility as the world’s biggest polluter in historical terms.

United Nations climate summits require consensus, so one country can crater an entire agreement. That’s led some to fear that a team from the Trump administration could block even incremental progress in Belém.

Under the 2015 Paris climate agreement, the United States and 197 other countries made voluntarily pledges to hold average global temperature rise to “well below” 2 degrees Celsius, and preferably closer to 1.5 degrees, compared to preindustrial levels. The world has already warmed about 1.3 degrees Celsius.

Every fraction of a degree of additional warming could mean tens of millions more people worldwide exposed to dangerous heat waves, wildfires, water and food shortages, and coastal flooding, scientists have said.

At the gathering that starts Thursday at the edge of the Amazon in Belém, countries are expected to deliver new, more ambitious plans to cut the carbon dioxide, methane and other greenhouse gases they emit.

Ms. Tubiana said the rest of the world would persevere without the Americans. From here on out, she said, “we have to act with or without the U.S.”

This year’s summit is set to begin with two days of speeches from heads of state and government, followed by about two weeks of negotiations among foreign ministers and other senior diplomats from about 140 countries.

Not only is the White House not sending high level representatives, it may not send any technical staff, either. It has been clear for months that Mr. Trump, who is withdrawing the United States from the Paris Agreement, never seriously considered making an appearance.

“President Trump will not jeopardize our country’s economic and national security to pursue vague climate goals that are killing other countries,” said Taylor Rogers, a White House spokeswoman, echoing language Mr. Trump used at the United Nations General Assembly in September, when he claimed that countries pursuing clean energy “would fail.”

Still, a group of about 100 American leaders, mostly Democratic state and local officials, is expected in Brazil to send a message that mayors, governors and business leaders still prioritize climate change even if Mr. Trump does not. Gov. Gavin Newsom of California, a Democrat who has emerged as President Trump’s chief antagonist, announced on Wednesday that he would attend the talks in Belém.

“As the president of the United States turns his back on people and the planet, California is inking global partnerships focused on creating jobs and cutting toxic pollution,” Mr. Newsom said in a statement.

Several big companies — including GE Vernova, Bank of America and Bayer — also will be on the ground, said Marty Durbin, who leads the energy institute at the U.S. Chamber of Commerce.

“The business community hasn’t walked away from this, even with the Trump administration minimizing it and pulling out,” Mr. Durbin said.

Because of the federal government shutdown, some Democratic lawmakers may pay their own way to attend as part of the Sustainable Energy and Environment Caucus, said Max Frankel, director of the nonprofit arm of the caucus. Other members of Congress, including Senator John Curtis, a Utah Republican, have said they were forced to cancel their plans for Belém entirely.

The absence of an official American delegation is a departure from previous Republican administrations.

In 2001 the United States withdrew from the Kyoto Protocol, the world’s first global climate agreement, which had been signed three years earlier by President Bill Clinton. But the George W. Bush administration still participated in annual talks.

And even when Mr. Trump first withdrew from the Paris Agreement, during his first term in 2017, he continued to send high ranking State Department officials to the U.N. climate summits to at least nod toward the need to reduce global greenhouse gas emissions.

Mr. Trump has signed multiple trade deals that require Japan, Korea, the European Union and other trading partners to buy billions of dollars worth of gas from the United States.

In August the Trump administration aligned with Saudi Arabia to scuttle an international limit on the production of plastics, which are made from petroleum. Last month the United States and Qatar joined forces to oppose European Union sustainability rules that require companies to identify and address the adverse environmental impacts of their actions.

That came on the heels of what is perhaps the Trump administration’s greatest anti-climate triumph: joining Saudi Arabia and Russia to thwart what would have been the first-ever global fee on shipping emissions. Trump administration officials openly threatened countries with tariffs and levies if they supported the carbon fee and later boasted of having deployed an “all hands on deck” pressure campaign.

Some argue the fear of maneuvering by the United States to impede climate talks is overblown. For one thing, there’s almost no one remaining in the State Department who knows the intricate U.N. process, since many employees were fired, reassigned or accepted offers to leave the government.

Under U.N. rules, the United States is still technically a party to the Paris Agreement until Jan. 27. It also remains a member of the U.N. body that convenes nations annually to monitor global progress on tackling climate change.

Conservatives and others who oppose efforts to address climate change also want the United States to stay away from Belém.

Seventeen Republican attorneys general, led by John McCuskey of West Virginia, sent a letter to the administration last month arguing that sending a delegation “would do little more than lend credibility” to the global climate talks.

“At a time when demand for energy is greater than ever, the prior administration embraced COP policies that dismantled — rather than supported — coal, oil, and gas production,” the attorneys general wrote. “The COP and other international actors favor less reliable and more expensive renewable energy sources, and that preference has proven harmful to American energy stability.”

Senator Jim Justice, a West Virginia Republican whose family owns several coal companies, said he did not have a strong position on whether the United States should take part in the talks. But with energy demand rising, in part because of the rapid growth of data centers, a transition away from fossil fuels threatens American security, he said.

“We know that we’re going to have an energy meltdown in this country and we have got to have our fossil fuels today like crazy,” Mr. Justice said. “If you knew you had to have your fossil fuels like crazy would it make sense to go to a climate change summit? Maybe not.”