Hours after Swedish climate activist Greta Thunberg was featured on Time magazine's cover as the 'Person of the Year', United States President Donald Trump mocked the 16-year-old and told her to work on her 'anger management' problem. "So ridiculous. Greta must work on her Anger Management problem, then go to a good old-fashioned movie with a friend! Chill Greta, Chill!" Trump tweeted. So ridiculous. Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill! — Donald J. Trump (@realDonaldTrump) December 12, 2019 In a riposte to Trump's critical remarks, Thunberg changed her Twitter bio to this: "A teenager working on her anger management problem. Currently chilling and watching a good old fashioned movie with a friend". The teenager, who made headlines by angrily thundering “How Dare You” at world leaders during a UN Climate Summit for their inaction, was honoured by the magazine on Wednesday. READ | ‘Go Greta Go!’: Netizens cheer for climate change activist for becoming youngest TIME Person of the Year Trump's tweet was met with criticism, with many calling out the US President for targetting a child. "You can't simply congratulate a teenager for headlining a major publication?" read a user's response to Trump's post. "I wasn't on the cover of time waaaaaaahhhhh!” pic.twitter.com/Vcmjg8fGDE — Random.Internet.BOT (@Thereapper69) December 12, 2019 Right.. Greta's anger management.. pic.twitter.com/35FwdGq2aF — Mark Stern (@mfstern) December 12, 2019 Karma, can you hurry up and get to work on this guy? — Roland Scahill (@rolandscahill) December 12, 2019 Climate change denier says what now? — Jon Fish 🐠 (@lionel_jon) December 12, 2019 Jealous much pic.twitter.com/YKYFTtg3AX — SMFH (@girlpowernow1) December 12, 2019 You can't simply congratulate a teenager for headlining a major publication? — Steward Beckham (@iTweetyNerd) December 12, 2019 Thunberg is the youngest individual ever to be named TIME’s Person of the Year. The publication said the annual honour is historically accorded to people who worked their way up the ladders of major organisations and were at home in the corridors of power.