John Kerry, the US special envoy on climate, is stepping down from his post in the coming weeks, US media reported on Saturday.
The 80-year-old politician has played a key role in the Biden administration's efforts to fight climate change over the past three years.
The decision to step down comes a month after Kerry played an important part in helping broker an international deal in Doha for countries worldwide to transition away from fossil fuels.
It wasn't immediately clear who would succeed him.
Kerry, however, wants to help Joe Biden's presidential reelection campaign by publicizing the president's work in combatting global warming, according to the media reports.
Placing climate high on the agenda
Biden tapped Kerry shortly after the November 2020 election to take on the newly created role of climate envoy.
Biden tasked Kerry with restoring US engagement in international climate talks after his predecessor, President Donald Trump, withdrew the US from the 2015 Paris climate agreement.
Kerry has spent the last three years trying to convince other countries to up their commitments on climate change.
He worked effectively with China on climate-related issues despite complicated diplomatic relations between Beijing and Washington.
Kerry has also led the US delegation at the last three UN climate summits.
Furthermore, he has a seat on the White House National Security Council, marking the first time an official on that body was dedicated to the climate issue.
"John Kerry's tireless work to deliver global progress on the climate crisis has been heroic," former Vice President Al Gore, who has focused primarily on climate in his post-public office life, said in a statement Saturday.
"He has approached this challenge with bold vision, resolute determination, and the urgency that this crisis demands. For that the US and the whole world owe him a huge debt of gratitude."
A leading drafter of the 2015 Paris climate accords
Prior to becoming the US climate envoy, Kerry served as secretary of state under Democratic former President Barack Obama.
In this role, he helped broker the 2015 Paris climate agreement.
Under the deal, countries around the world committed to limiting the Earth's warming to "well below" 2 degrees Celsius and preferably to the safer 1.5C threshold.
Kerry had previously served as a Democratic senator from Massachusetts for nearly three decades.
He was his party's 2004 presidential nominee but lost the race to Republican incumbent George W. Bush.