“I want you to listen to the scientists,” Thunberg said in her testimony before the House Select Committee on the Climate Crisis, where she appeared with other youth leaders. “I want you to unite behind science. And then I want you to take action.”

Instead of prepared remarks, Thunberg submitted a 2018 report on global warming by the Intergovernmental Panel on Climate Change, which warned about the impacts of global warming of 1.5°C that researchers say is likely between 2030 and 2052 if it continues at the current rate.

“This is not political views or my opinions,” she said. “This is science.”

The hearing was part of a series of events intended to raise awareness of global warming before a planned “climate strike” on Friday, when students around the world are being encouraged to walk out of schools and jobs to demand action on climate change before the annual United Nations General Assembly later this month.

Thunberg chastised members of the Senate Climate Change Task Force on Tuesday for inaction.

“Please save your praise. We don’t want it,” Thunberg said. “Don’t invite us here to tell us how inspiring we are without doing anything about it because it doesn’t lead to anything.”

Jamie Margolin, a 17-year-old climate change activist from Seattle, also scolded committee members on Wednesday for empty praise.

“You’re promising me lies,” Margolin said. “Everyone who will walk up to me after this testimony saying I have such a bright future ahead of me will be lying to my face. It doesn’t matter how talented we are, how much work we put in, how many dreams we have. The reality is, my generation has been committed to a planet that is collapsing.”

President Trump and his administration have been widely criticized for rolling back Obama-era environmental protections, withdrawing from the Paris Climate Accord and resisting the conclusions by the vast majority of scientists that global warming has been caused by humans.

On Monday, Thunberg met with former President Barack Obama at his Washington, D.C., offices.

Just 16, @GretaThunberg is already one of our planet’s greatest advocates. Recognizing that her generation will bear the brunt of climate change, she’s unafraid to push for real action. She embodies our vision at the @ObamaFoundation: A future shaped by young leaders like her. pic.twitter.com/VgCPAaDp3C

— Barack Obama (@BarackObama) September 17, 2019

“No one is too small to have an impact and change the world,” Thunberg said in a video posted to Twitter by the former president’s charitable foundation. “So do everything that you can.”

Thunberg, who has been nominated for a Nobel Prize for her work raising awareness about climate change, has become an inspirational figure for fellow teens. Last month, she sailed from Europe to the United States on a zero-emission yacht.

Arriving in New York City after her 15-day trip across the Atlantic Ocean, she was asked if she had a message for Trump.

“My message for him is listen to the science,” Thunberg said. “And he obviously doesn't do that.