Former first lady Michelle Obama wrote a public note of support to Greta Thunberg overnight, following President Donald Trump's dismissal of the teen climate change activist after she was named Time's Person of the Year.

"Don't let anyone dim your light," Obama wrote, in part. "Ignore the doubters and know that millions of people are cheering you on."

.@GretaThunberg, don’t let anyone dim your light. Like the girls I’ve met in Vietnam and all over the world, you have so much to offer us all. Ignore the doubters and know that millions of people are cheering you on. — Michelle Obama (@MichelleObama) December 13, 2019

After the magazine's announcement on Thursday, Trump — who was shortlisted for the honor — mocked the Swedish teenager and accused her of having an anger management problem.

Trump was named 2016's Person of the Year and appears to have a soft spot for Time magazine: Several of his golf properties include a fake copy of the magazine with him on the cover, according to The Washington Post.

"So ridiculous," he wrote Thursday of Time's 2019 choice.

So ridiculous. Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill! https://t.co/M8ZtS8okzE — Donald J. Trump (@realDonaldTrump) December 12, 2019

Thunberg spoke movingly in a speech at the United Nations in September, expressing anger over climate change.

"I shouldn't be up here," she said. "I should be back at school on the other side of the ocean. Yet, you all come to us young people for hope. How dare you? You have stolen my dreams and my childhood with your empty words."

Thunberg has Asperger's syndrome and has spoken publicly about the social challenges it creates, while also attributing her passionate activism in part to the neurological makeup she's called her "superpower."

Following Trump's barbs, Thunberg changed her Twitter profile to describe herself as "a teenager working on her anger management problem. Currently chilling and watching a good old fashioned movie with a friend."

Trump's re-election campaign, meanwhile, posted a copy of the Time Thunberg cover with the president's head photoshopped onto her body.