But Mr Trump has refused to concede that he has lost and continues to frantically post to Twitter, including in all-caps, alleging “BALLOT COUNTING ABUSE!” and “WE WILL WIN!”
“It appears after that follows diminishing or denying democracy itself. A global phenomenon - all for greed and power.”
Ms Thunberg, who stars in the documentary “I Am Greta,” coming out Friday on Hulu, has long been reticent to comment on political leaders but has made an exception for Mr Trump around the November election.
Last Thursday, as Mr Trump raged on Twitter over unfounded allegations of voter fraud, she tweeted in reply to one of the president's "STOP THE COUNT!" tweets.
"So ridiculous. Donald must work on his Anger Management problem, then go to a good old fashioned movie with a friend! Chill Donald, Chill!" the 17-year-old wrote.
The message came almost a year after Mr Trump had tweeted about Ms Thunberg, apparently upset that she was named Time magazine's person of the year over him.
“So ridiculous. Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill!” he wrote in 2019.
In October, the Swedish activist showed support for Mr Biden, urging voters concerned about the environment to make their voices heard in the election.
She said in a tweet that she never engages in party politics, but that “the upcoming US elections is above and beyond all that”.
“From a climate perspective it's very far from enough and many of you of course supported other candidates. But, I mean you know damn! Just get organised and get everyone to vote #Biden,” she wrote.
Ms Thunberg sparked a global protest movement after she began striking over the climate crisis outside the Swedish parliament in 2018.
Register for free to continue reading
Registration is a free and easy way to support our truly independent journalism
By registering, you will also enjoy limited access to Premium articles, exclusive newsletters, commenting, and virtual events with our leading journalists
Already have an account? sign in
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies