John Kerry, President Biden’s special envoy for climate, plans to step down by spring, ending a three-year run in a major diplomatic role that was created especially for him and which will face an uncertain future with his departure.

Mr. Kerry, 80, has served as the president’s top diplomat on climate change since early 2021, working to cajole governments around the world to aggressively cut their planet-warming greenhouse gas emissions.

He led the U.S. negotiating team through three United Nations climate summits, reasserting American leadership after the country withdrew from the Paris climate agreement during the Trump administration. Mr. Kerry championed cooperation on global warming between the United States and China, the world’s two largest polluters, during times of tension.

On Wednesday, Mr. Kerry met with Mr. Biden in the White House to inform the president of his intention to resign, according to one person familiar with the meeting. On Saturday, his staff learned of his decision at a hastily arranged meeting, said the person, who asked to remain anonymous in order to discuss personnel matters.

Mr. Kerry told staff that he intended to depart in the coming months. He is widely expected to get involved in the 2024 presidential campaign to help raise awareness of Mr. Biden’s work on climate change. No successor has yet been tapped.

The State Department confirmed Mr. Kerry’s planned exit. The White House didn’t respond on Saturday to a request for comment. Mr. Kerry’s plans were first reported by Axios.

In the meantime Mr. Kerry is planning to attend the World Economic Forum in Davos, Switzerland, next week as well as a meeting of the International Energy Agency in Paris in February.

A former Massachusetts senator, Democratic presidential nominee and secretary of state under President Barack Obama, Mr. Kerry brought a celebrity status to the global climate summits. President Biden created the role specifically for Mr. Kerry, and he was also granted a seat on the National Security Council in the White House, marking the first time an official on that body was dedicated specifically to climate change.

Widely regarded as a tireless crusader for climate action, Mr. Kerry traveled to 31 countries in an effort to restore confidence in the U.S. on climate change and persuade other countries to do more to help keep the average global temperature from rising above 1.5 degrees Celsius compared with preindustrial levels. That’s the threshold beyond which scientists say the dangers of global warming — including worsening floods, droughts, wildfires and ecosystem collapse — grow considerably.

Humans have already heated the planet by an average of 1.2 degrees Celsius since the 19th century, largely by burning fossil fuels.

Mr. Kerry played a key role in urging President Biden to set a more aggressive target for greenhouse gas emissions for the United States, which the president did by pledging to cut emissions roughly in half by 2030.

But Mr. Kerry’s record in persuading other nations to act was mixed.

More than 30 countries agreed to bolster their climate targets ahead of a United Nations climate summit in Glasgow, Scotland in 2021, a fact largely credited to Mr. Kerry’s diplomatic efforts. Yet his ability to move China, the world’s largest climate polluter, often faltered.

In November the United States and China agreed to jointly tackle global warming by ramping up wind, solar and other renewable energy with the goal of displacing fossil fuels. That deal was significant and came together after years of diplomacy between Mr. Kerry and his Chinese counterpart Xie Zhenhua. Still it fell short of a promise by China to phase out its heavy use of coal, the dirtiest fossil fuel, or to stop permitting and building new coal-burning plants.

Mr. Kerry’s decision to step down comes on the heels of an announcement by Mr. Xie that he, too is retiring, raising concerns about what climate diplomacy will look like after two people particularly eager for cooperation are gone.

Former Vice President Al Gore in a statement on Saturday called Mr. Kerry’s work on climate change “heroic.” But the future of the climate envoy role in the United States is uncertain.

Mr. Kerry wasn’t subject to Senate confirmation when he was appointed, a fact that angered some Republicans. Under a spending-bill provision in 2022, all new special-envoy positions reporting to the Secretary of State will have to win Senate approval.

G.O.P. lawmakers have criticized Mr. Kerry’s role and have said that he was undermining the United States by negotiating with China. At a heated congressional hearing last year Republicans also accused Mr. Kerry of flying on private jets. Mr. Kerry called that a “stupid” lie, saying that while his wife owns a jet he hasn’t used one in his role as climate envoy.