Greta Thunberg isn’t taking President Trump’s online abuse lying down.

The teenage climate activist tweaked her Twitter bio to hit back at Trump after the president warned her to “chill” about the crisis threatening to destroy the planet.

“A teenager working on her anger management problem,” Thunberg described herself on the social media platform after changing the bio Thursday morning. “Currently chilling and watching a good old fashioned movie with a friend.”

Thunberg, the newly minted Time magazine Person of the Year, was referring to Trump’s breakfast tweet in which he sought to denigrate the teen activist.

“So ridiculous,” Trump wrote of the honor. “Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill!”

Trump regularly downplays or denies the effects of climate change despite an undeniable scientific consensus that it is real and caused by human activity.

But he may learn the dangers of being a senior citizen seeking to do battle on Twitter with a social media-savvy teen.

Thunberg launched a one-girl weekly climate protest and turned it into a global protest movement.

Trump’s attack on a girl 60 years his junior is especially unseemly because First Lady Melania Trump has made combating cyberbullying one of her signature issues using the hashtag #BeBest.

The First Lady recently slammed a law professor for making a joke about the name of the Trumps’ teenage son, Barron, at the impeachment hearings.