US President-elect Joe Biden is to nominate one of the leading architects of the Paris climate agreement as his climate envoy.
Ex-US Secretary of State John Kerry was one of several named for top positions by the Biden transition team on Monday.
It marks a big break with the climate policy under the Trump administration as Mr Biden makes good on his campaign pledge to tackle climate change.
Other key picks include long-time aide Antony Blinken as secretary of state.
Reports say former Federal Reserve chair Janet Yellen will be the choice for treasury secretary.
The nomination comes as calls are growing for President Donald Trump to concede the election.
He has made unsubstantiated claims of electoral fraud and is continuing to pursue legal challenges over the result.
Mr Biden is projected to beat President Trump by 306 votes to 232 when the US electoral college meets to formally confirm the winner on 14 December. This is far above the 270 votes he needs.
In a statement following the announcement on Monday, Mr Biden said: “I need a team ready on day one to help me reclaim America’s seat at the head of the table, rally the world to meet the biggest challenges we face, and advance our security, prosperity, and values. This is the crux of that team.”
Some of the positions require confirmation in the US Senate.
Who is John Kerry and what will he do?
Mr Kerry was chosen for the role of special presidential envoy for climate.
The Biden transition team said the position would see him “fight climate change full-time”. He is also set to be the first official dedicated to climate change to sit on the National Security Council.
Mr Kerry signed the Paris climate agreement on behalf of the US in 2016. The deal committed countries to working to limit the global temperature rise.
Under Mr Trump, the US recently became the first country to formally withdraw from the agreement. But Mr Biden has said he plans to rejoin the accord as soon as possible.
In 2019, Mr Kerry launched a coalition of world leaders and celebrities – dubbed World War Zero – to call for climate change action and net zero carbon emissions.
Following news of his new role on Monday, he tweeted: “America will soon have a government that treats the climate crisis as the urgent national security threat it is.”
Mr Kerry previously served as secretary of state during Barack Obama’s second term as president. A veteran Democratic politician, he lost to incumbent Republican George W Bush in the 2004 presidential election.
He was a senator for 28 years and chairman of the foreign relations committee.
He endorsed Mr Biden to be the Democratic Party’s candidate in the 2020 race and joined him on the campaign trail.
What about the other roles?
Mr Blinken was nominated as secretary of state – the most important foreign policy position. The 58-year-old was deputy secretary of state and deputy national security adviser during the Obama administration, in which Mr Biden served as vice-president.
BBC