President Joe Biden has assured foreign governments that the United States will make steep cuts in greenhouse gas emissions over the next decade, a pledge designed to reassert U.S. leadership on climate change and spur other industrial powers to make similar commitments in the run-up to Biden’s climate summit next week.

The move comes several weeks after the release of a United Nations study showing that the world is lagging woefully behind targets set under the Paris climate agreement to prevent global temperature from rising more than 1.5 degrees Celsius above preindustrial levels, a threshold that climate scientists fear could wreak severe damage on the globe. It comes on the eve of a major speech scheduled for Monday by U.S. Secretary of State Antony Blinken, who is expected to detail American plans to curb emissions.

It’s unclear just how ambitious the Biden administration will be or how it plans to implement those cuts. Sources said the administration is mulling the possibility of sharply increasing the commitment made by former President Barack Obama, who pledged to cut emissions 26 to 28 percent from 2005 levels by 2025. Experts say Biden would have to use a mix of executive orders and legislation to push for steeper cuts of as much as 50 percent by 2030—and it’s not clear how durable such changes would be given likely court battles and changes in control of Congress and the White House in coming years.

The upcoming virtual Leaders Summit on Climate, which will open on Earth Day, poses a major test of Biden’s capacity to reassert American leadership on climate, following four years of denial by the Trump White House that climate change was anything more than a fraud designed to hamstring American industry. The White House recently invited some 40 world leaders—including Presidents Xi Jinping of China, Vladimir Putin of Russia, and Jair Bolsonaro of Brazil, as well as German Chancellor Angela Merkel, Indian Prime Minister Narendra Modi, and Japanese Prime Minister Yoshihide Suga—for two days of climate discussions. It’s a resurrection of the Major Economies Forum on Energy and Climate, an association of the biggest emitters that was first convened by Obama to coordinate climate policy but that was largely abandoned by President Donald Trump.

“The world is already experiencing the devastating impacts of climate change. Science makes clear that unless we dramatically scale up our efforts over the course of this decade, we will condemn future generations to incalculable harm,” Biden warned in a private letter to the countries invited to attend. “It is incumbent on us as leaders to do all within our power to stem this rising global threat,” he urged, adding that the goal must be to limit the temperature increase to 1.5 degrees.

The talks will begin on April 22 with a session dedicated to raising the climate ambitions of governments, according to a copy of a preliminary agenda seen by Foreign Policy. That will be followed by a session to mobilize financing for developing countries to ease the destruction wrought by global warming and improve resilience. In a separate meeting to be hosted by members of the president’s cabinet, discussion will focus on the role that subnational groups—businesses, cities, and states—can play in helping countries adapt to the challenges posed by climate change. That session will also address the impact that climate can have on international security.

World leaders will convene online for a second day to explore the economic benefits of transitioning into an emission free future, while discussing “innovative technologies” that can help countries mitigate the devastation wrought by global warming. In advance of the meeting, the White House has prepared a draft executive order directing the federal government to “measure, mitigate and disclose climate risks facing federal agencies,” Politico reported.

A State Department spokesperson confirmed that the United States plans to announce an “ambitious new climate target” in the coming days, adding that it invites other countries to “announce their plans for enhanced climate ambition.”

Characterizing the summit as a “key milestone on the road” to the November climate conference in Glasgow, Scotland, the spokesperson said the meeting “is aimed at setting the world up for success on multiple fronts as we work to address the climate crisis, including emissions reductions, finance, innovation and job creation, and resilience and adaptation.”

The goal of the summit is to prod more countries to do more to rein in emissions ahead of the Conference of Parties climate summit in Glasgow later this year. A Feb. 26 U.N. report estimated that the world is on pace to reduce global greenhouse levels barely half a percentage point from 2010 levels by 2030. To hit the 1.5-degree target, nations would have to reduce emissions by 45 percent by that date, and become net-zero by 2050.

“Climate catastrophe is looming,” U.N. Secretary-General António Guterres said in February at the Munich Security Conference. Guterres said that currently, countries representing more than 65 percent of global emissions have committed to achieve net-zero emissions by the middle of the century. But he said the world needs to bring that number to 90 percent by the opening of the Glasgow conference.

The United States has been using its own timetable for commitments to curb greenhouse gases, such as Obama’s plans for modest cuts by 2030. That’s the first thing Biden plans to ramp up. In his letter to invitees, Biden pledged: “By the time of the Leaders Summit, the United States will put forward an ambitious climate target for 2030 as our new nationally determined contribution under the Paris Agreement. I urge you all to also come to the Summit prepared to share how your government will contribute to keeping the 1.5 degree Celsius goal within reach.”

Biden did not reveal American emission targets in the letter. But significantly expanding the scope of Obama’s planned reductions would win praise from business and the environmental community.

“That is what a lot of the environmental and international community have been pushing for, so that’d be well received,” said Pete Ogden, the vice president for energy, climate, and the environment at the United Nations Foundation.

The administration is under mounting pressure to hit those more ambitious targets. A group of more than 300 businesses and investors who employ nearly 6 million American workers and manage more than $1 trillion in assets recently urged Biden in a joint letter to reduce emissions by 50 percent below 2005 levels in the next decade. Earlier this week, the Union of Concerned Scientists appealed to Biden in a letter signed by more than 1,500 scientists to hit the same goal. “Hundreds of scientists have affirmed that the ambitious goal of cutting emissions in half by 2030 is scientifically feasible and the minimum threshold of what’s necessary,” said Rachel Cleetus, the policy director and lead economist in the Climate and Energy Program at the scientist union, in a statement.

Biden’s climate envoy, John Kerry, has been traveling the world in recent weeks to try to convince key greenhouse gas-emitting countries, including China and India, to embrace more ambitious targets. The hope is that the United States, by opening next week’s meeting with a bold pledge, can nudge countries like Canada, South Korea, and Japan to ratchet up their own targets.

“[W]e all must step up and do more if we are to ensure the [Paris] Agreement’s success,” Biden wrote. “I am fully committed to working with you to strengthen global climate ambition heading into the U.N. Climate Change Conference this November in Glasgow.”

“They have worked hell for leather to have that ready to announce next week,” said Thom Woodroofe, a senior advisor in multilateral affairs to Kevin Rudd, the president of the Asia Society Policy Institute. “If the Americans have that arrow in their quiver they can lean on Japan and Canada and Australia and others and say, ‘We’ve done it and we want you to do it.’”

Woodroofe said he believes there may be some concrete commitments from some countries over the next week, adding that Japan’s Suga, who is visiting Washington, this week for a meeting with Biden, may foreshadow Japanese short-term commitments. Suga is expected to announce a new emission target of around 50 percent below 2013 levels by 2030, according to the New York Times. Before Biden’s inauguration, Tokyo refused to update its 2030 goals.

Canada is also expected to announce a new commitment to reduce greenhouse gas emissions by 2030 at the Biden summit.

“There is a kind of momentum building,” Woodroofe said.

He said he also expects China will make some fresh commitments in the coming year, though it’s unlikely a big announcement will come at a Biden-convened meeting. “The question is whether there is a utility for them geopolitically doing it next week, or at another moment,” he said. (That may come at a Chinese-hosted Boao Forum for Asia, which takes place from April 18 to 21.)

China has made big pledges—but little real progress. Xi, speaking to the U.N. General Assembly last year, committed to a peak in Chinese emissions by 2030 and carbon neutrality by 2060. But even that won’t be enough to meet the 1.5-degree threshold. What’s needed is for China to dramatically scale back reliance on coal-powered plants, something it has been unwilling to do.

“We must insist Beijing do more to reduce emissions and help tackle the worldwide climate crisis,” the State Department spokesperson said. “China represents almost 30 percent of global emissions, in addition to its carbon-intensive investments abroad.” Germany and France have also pressed China to take bold steps, including curtailing its reliance on coal in the Belt and Road Initiative. Merkel and French President Emmanuel Macron invited Xi to participate in a climate and energy session on Friday, less than a week ahead of Biden’s summit. Xi has agreed to participate.

Li Shuo, a Beijing-based environmentalist with Greenpeace, said that China runs the risk of undercutting its leadership role on climate if it comes empty-handed to the summit.

“Many people will question if it’s worth working or engaging with China at all,” he said. But if China makes a significant commitment to rein in coal, it will send a strong signal that the United States and China will be able to work constructively on climate even as they spar over a laundry list of more toxic political issues, from human rights in Xinjiang and Hong Kong to trade.

Expectations of action by India, the world’s third-largest emitter of greenhouse gases after China and the United States; Brazil; and Russia are much lower. In a visit to India earlier this month, Kerry pressed Modi on the need for “ambitious climate action.” Experts are skeptical.

Sunita Narain, an Indian environmentalist, said that she sees little pressure on India to make bold commitments at the Biden summit, unless there is a major ramp-up of cuts from the developed world.

“I don’t know why Kerry is visiting,” Narain said.

“Kerry should be pressuring his own country. The question is how serious is Biden, and what is he going to do,” she said. “We need the U.S. to walk the talk.”