Around the world, millions of people — a lot of them young students — took to the streets to demand action against climate change ahead of Saturday’s first-ever UN Youth Climate Summit in New York City.

In New York, students skipped school by the thousands to make their way to Manhattan’s Foley Square, where Greta Thunberg, the 16-year-old Swedish climate activist and founder of main organizing group #FridaysForFuture, led an enormous march down Broadway and to Battery Park. In clever signs and deafening chants, crowds made themselves very clear — the Earth as it exists now is dying and if nothing changes, it will be too late to do anything about it.

BuzzFeed News sent photographers Erin Lefevre and Avery White to meet some of the teens and ask them a simple question that cuts to heart of why they march: “What will you miss about Earth when it’s too far gone to be saved?”

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