Former US Secretary of State John Kerry will act as “climate tsar” when US President-elect Joe Biden takes office.
Mr Kerry was one of several people named for top positions by the Biden transition team on Monday.
Other key picks include Avril Haines as the first woman to lead intelligence, and long-time Biden aide Antony Blinken as secretary of state – the most important foreign policy position.
It comes as calls are growing for Donald Trump to concede the election.
He has made unsubstantiated claims of widespread 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.”