President Donald Trump posted a mocks tweet to 16 years old climate activist who brought headlines this week for her address at the United Nations.

Trump quoted a particularly sensitive line from Greta Thunberg’s address to the Climate Action Summit in a late-night tweet last Monday.

In it, the Swedish teen said that ‘people are dying’ and ‘we are at the beginning of mass extinction.”

‘She seems a very happy young girl looking forward to a brilliant and wonderful future,’ Trump addressed over Thunberg’s quote.

Mr Trump is also in New York for the U.N. posted the word in a series of night tweets.

Thunberg has Asperger’s syndrome and has earlier chided her critics on Twitter: ”I’m sometimes a bit distinct from the norm,”she posted on Twitter last year. “And given the right circumstances being mixed is a superpower.”

Trump, who once described climate change a hoax perpetrated by the Chinese, was supposed to skip the climate summit at the U.N. on Monday but rather make a surprise visit for approximately 15 minutes.

Many world leaders assembled here are angry that the president is acting to pull the U.S. out of the 2016 Paris climate agreement, but Trump has debated that it puts the country at a competing disadvantage.