BRUSSELS — President Biden joined with leaders of the world’s wealthiest nations on Sunday to take action aimed at holding down global temperatures, but failed to set a firm end date on the burning of coal, which is a primary contributor to global warming.

Mr. Biden and six other leaders of the Group of 7 nations promised to cut collective emissions in half by 2030 and to try to stem the rapid extinction of animals and plants, calling it an “equally important existential threat.” They agreed that by next year they would stop international funding for any coal project that lacked technology to capture and store carbon dioxide emissions and vowed to achieve an “overwhelmingly decarbonized” electricity sector by the end of the decade.

It was the first time that the major industrialized economies, which are most responsible for the pollution that is warming the planet, agreed to collectively slash their emissions by 2030, although several nations had individually set those same goals, including the United States and the United Kingdom.

But energy experts said the failure of the G7 nations, which together produce about a quarter of the world’s climate pollution, to agree on a specific end date for the use of coal weakened their ability to lean on China to curb its own still-growing coal use. It may also make it more difficult to convince 200 nations to strike a bold climate agreement at a United Nations summit in Scotland later this year.

The G7 leaders also declined to pledge significant new funding to help developing countries both manage climate impacts as well as pivot away from burning oil, gas and coal.

“It’s very disappointing,” said Jennifer Morgan, the executive director of Greenpeace International. “This was a moment when the G7 could have shown historic leadership, and instead they left a massive void.”

Scientists have warned that the world needs to urgently cut emissions if it has any chance to keep average global temperatures from rising above 1.5 degrees Celsius, compared with preindustrial levels. That’s the threshold beyond which experts say the planet will experience catastrophic, irreversible damage. Temperature change is not even around the globe; some regions have already reached an increase of 2 degrees Celsius.

Mr. Biden opened his first foreign trip as president last week by declaring that on issues like climate, “the United States is back.” After four years in which President Donald J. Trump mocked the established science of climate change, discouraged the development of clean energy while favoring fossil fuels and refused to cooperate with allies on environmental issues, Mr. Biden was once again part of a unanimous consensus that the world needs to take drastic action to prevent a global disaster.

“President Biden has committed to tackling the climate crisis at home and abroad, rallying the rest of the world at the leaders summit, G7, and beyond to reach for bold targets within the next decade,” said Daleep Singh, deputy national security adviser. “While the previous administration ignored the science and consequences of climate change, our administration has taken unprecedented actions to prioritize this on the global stage.”

In addition to rejoining the 2015 Paris Agreement that Mr. Trump abandoned, Mr. Biden has promised to cut the United States’ greenhouse gas emissions by 50 percent to 52 percent below 2005 levels by 2030, and to eliminate fossil fuel emissions from America’s power sector by 2035.

But it was the United Kingdom, along with some other European countries, that had pushed aggressively during the summit this year to stop burning coal for electricity by a specific date in the 2030s. Burning coal is the largest source of carbon dioxide emissions, and after a pandemic-year retreat, demand for coal is expected to rise by 4.5 percent this year, according to the International Energy Agency.

Instead, the final language of the leaders’ “communiqué” makes only a vague call to “rapidly scale up technologies and policies that further accelerate the transition away” from coal without carbon capture technology.

The debate at the summit over how quickly to abandon coal came at a particularly delicate moment for Mr. Biden, whose push for a major infrastructure package in a closely divided Congress may depend on the vote of one Democratic senator: Joe Manchin of coal-dependent West Virginia.

In a statement to The New York Times, Mr. Manchin noted “projections showing that fossil fuels, including coal, will be part of the global energy mix for decades to come” and praised the Biden administration for recognizing the need to develop clean energy technologies. But advocates for faster action said concerns about placating Mr. Manchin appeared to have prevented more aggressive steps.

“Once again Joe Manchin is casting a heavy shadow,” said Alden Meyer, a senior associate at E3G, a European environmental think tank.

The United States in particular had a chance to lead countries in strong language to move away from fossil fuels this decade, Ms. Morgan of Greenpeace said. But “it doesn’t seem like they were the ambition setters at this G7.”

Other leading climate change advocates and diplomats called the overall climate package a mixed bag.

Mr. Biden and the other leaders said they would deliver $ 2 billion to help nations pivot away from fossil fuels, in what leaders hope will be a global transition to wind, solar and other energy that does not produce planet-warming carbon dioxide emissions. And they agreed to raise their contributions and meet an overdue pledge of mobilizing $ 100 billion a year to help poorer countries cut emissions and cope with the consequences of climate change, though firm dollar figures were not on the table.

Laurence Tubiana, C.E.O. of the European Climate Foundation who served as France’s chief climate ambassador during the 2015 Paris negotiations, said she was pleased that nations would stop financing new coal projects without technology to capture and store emissions. It will mean an end to virtually all funding for new coal, since carbon capture technology is nascent and not widely used.

“That leaves China to decide now if they want to still be the backers of coal globally, because they will be the only one,” she said. But she said the financing package was lacking for developing countries, which are particularly vulnerable to floods, drought and other impacts of a climate crisis created by the industrialized nations.

G7 nations this week also backed Mr. Biden’s sweeping infrastructure plan to counter China’s multi-trillion-dollar Belt and Road Initiative. As part of that, countries promised to help the developing world rebuild from the Covid-19 pandemic in a way that takes climate change into account.

Wealthy nations had agreed in 2009 to mobilize $ 100 billion in public and private funding by 2020 in order to help poorer countries move to clean energy and adapt to the most severe consequences of climate change. But they have delivered only about $ 80 billion on that promise, according to the Organization for Economic Cooperation and Development. And most of that money is in the form of loans, not grants, making it difficult for poor countries to use, experts said.

“The G7 announcement on climate finance is really peanuts in the face of an existential catastrophe,” said Malik Amin Aslam, Pakistan’s climate minister. He called it a “huge disappointment” for his country and others that have had to spend more to cope with extreme weather, displacement and other impacts of global warming.

“At the least, countries responsible for this inescapable crisis need to live up to their stated commitments, otherwise the climate negotiations could well end in futility,” he warned.

A recent report from the International Energy Agency concluded that if the world is to stave off the most devastating consequences of global warming, major economies must immediately stop approving new coal plants and oil and gas fields.

At the summit, the seven countries addressed biodiversity loss, calling it a crisis on the same scale as climate change.

They said they would champion a global push to conserve at least 30 percent of the planet’s land and water by 2030 and would set up such protections within their own countries. These measures are needed, scientists say and the G7 reiterated, to help curb extinctions, ensure water and food security, store carbon and reduce the risk of future pandemics.

Today, about 17 percent of the planet’s land and 8 percent of its oceans are protected, according to the United Nations.

Environmental groups welcomed the inclusion of the 30 percent commitment but emphasized the need for action, which requires adequate financing. That’s the hard part, to be hammered out at a separate United Nations biodiversity conference that will be held in October in Kunming, China.

Because the world’s remaining intact ecosystems and biodiversity hot spots are unevenly distributed, scientists emphasize that it’s not enough for each country to carve out its own 30 percent. Rather, countries should work together to maximize the protection of areas that will yield the best returns on reversing the interdependent biodiversity and climate crises. Researchers have mapped suggestions.

The rights of local communities, including Indigenous peoples who have been better stewards of biodiversity, must be valued, advocates said. Protecting nature does not mean kicking people out, but rather ensuring that wild areas are used sustainably.

Robert Watson, a former chairman of two leading intergovernmental panels on climate change and biodiversity, praised the agreement for linking the two crises. But he said it needs to address the factors that are driving species loss, including agriculture, logging and mining.

“I do not see what actions will be taken to stop the causes,” Dr. Watson said.