"You come to us young people for hope. How dare you?" a visibly angry Thunberg told the high-level audience gathered for the UN Climate Action Summit in New York.
"You have stolen my dreams and my childhood with your empty words, yet I'm one of the lucky ones. People are suffering, people are dying, entire ecosystems are collapsing," thundered the 16-year-old Swedish girl, who has galvanized youth across the world to mobilize against climate change.
"We are at the beginning of a mass extinction, and all you can talk about is money and fairy tales of eternal economic growth," she said, holding back tears. "If you choose to fail us, we will never forgive you."
More than 60 world leaders are expected to attend the summit called by UN Secretary-General Antonio Guterres to talk about the climate crisis and policy solutions.
Merkel hears 'wake-up call'
German Chancellor Angela Merkel, whose government agreed on a climate package last week that was received with mixed reactions, told the gathering that the international community needs to listen to scientists and youth.
"We have all heard the wake-up call of youth," she said, referring to climate protests. "Germany has 1% of the world's population and 2% of the world's emissions."
Merkel described Germany's newly unveiled climate package as the beginning of a "profound transition" that will make the country climate neutral by 2050.
The German leader said climate change is a global problem and that industrial nations have been the primary source of greenhouse gas emissions, while developing nations are bearing the brunt of the crisis.
Complaint filed against five nations
Meanwhile, Thunberg and 15 other youngsters filed a complaint with the UN Committee on the Convention on the Rights of the Child.
The complaint alleges Germany, Argentina, Brazil, France, and Turkey knew about the negative impact on the environment of their carbon emissions and did nothing to prevent it.
"World leaders have failed to keep what they promised. They promised to protect our rights and they have not done that," Thunberg said.