The U.N. Climate Action Summit kicked off in New York Monday with world leaders calling for action to prevent “apocalyptic” climate change. U.N. Secretary-General António Guterres said his generation had “failed in its responsibility to protect our planet.” Sixteen-year-old Swedish climate activist Greta Thunberg fought back tears as she gave an impassioned address.

Greta Thunberg: “You have stolen my dreams and my childhood with your empty words. And yet I’m one of the lucky ones. People are suffering. People are dying. Entire ecosystems are collapsing. We are in the beginning of a mass extinction, and all you can talk about is money and fairy tales of eternal economic growth. How dare you!”

Trump later mocked the now world-renowned activist on Twitter, writing, “She seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!”

Meanwhile, Greta Thunberg and other youth climate activists filed an official complaint under the Convention on the Rights of the Child, calling on world leaders to protect future generations from climate catastrophe. We’ll have more on the historic action, and what took place at the summit yesterday, after headlines.