DAVOS, Switzerland — Greta Thunberg on Tuesday punched a hole in the promises emerging from a forum of the global political and business elite and offered instead an ultimatum: Stop investing in fossil fuels immediately, or explain to your children why you did not protect them from the “climate chaos” you created.

“I wonder, what will you tell your children was the reason to fail and leave them facing the climate chaos you knowingly brought upon them?” Ms. Thunberg, 17, said at the annual gathering of the world’s rich and powerful in Davos, a village on the icy reaches of the Swiss Alps.

Her remarks opened a panel discussion hosted by The New York Times and the World Economic Forum. The full transcript is available here.

“Our house is still on fire,” she added, reprising her most famous line from an address last year at the forum. “Your inaction is fueling the flames by the hour.”