15-year-old Greta Thunberg, a Swedish student, grabbed headlines this past week with her tough message for climate change negotiators at a United Nations climate summit in Poland.
"You are not mature enough to tell it like is," she said at a climate summit that ended on Sunday. "Even that burden you leave to us children."
Her remarks quickly gained attention on social media, and video of her speech was shared by leading climate scientists and officials. Vermont Sen. Bernie Sanders tweeted footage of her speech, saying she "called out world leaders for their global inaction on climate change."
The teenager spoke on behalf of Climate Justice Now, a global network of climate advocacy groups. Officials from nearly 200 countries gathered in Poland to set rules that will govern the Paris Agreement on climate change, which aims to limit global warming.
"You have ignored us in the past, and you will ignore us again," she told leaders. "You say you love your children above all else, and yet you are stealing their future in front of their very eyes."
While Thunberg is young, she's spent years working as a climate activist.
Earlier this year she went on strike from school, holding a sign outside the Swedish parliament building in Stockholm that read, "school strike for climate." Thunberg, who describes herself on Twitter as a 15-year-old climate activist with Asperger's, said she was inspired by the school walkouts in the United States that followed the Parkland school shooting.
"We have done this many times before and with so little results," she told CNN. "Something big needs to happen. People need to realize our political leaders have failed us. And we need to take action into our own hands."