The kids are not messing around. Across the planet today, in 100 countries and every state in the US, thousands upon thousands of children skipped school and took to the streets with a message for the adults: Save the world you broke.

The walkout was one of the biggest protests against climate change ever organized. And the organizers were children, inspired by Swedish climate activist and teenager Greta Thunberg, and led in the US by three young women: 13-year-old Alexandria Villasenor of New York City, 16-year-old Isra Hirsi of Minnesota, and 12-year-old Haven Coleman of Denver, Colorado. These are the kids who stand to inherit a scorched Earth. They want a world that won’t eat them alive, that won’t boil their oceans and destroy their crops. They want a future; if they have to miss class to get the adults to listen, they will.

“My GPA isn’t going to matter if I’m dead,” said an Oakland high-schooler named Bruck, 16, who’d crossed the bay to strike in front of Speaker of the House Nancy Pelosi’s office in San Francisco along with at least 1,000 other kids—ranging in age from toddlers with their parents to 18-year-olds. A member of the Youth vs. Apocalypse group that confronted California senator Dianne Feinstein last month, Bruck and his friends want Pelosi to cosponsor the Green New Deal resolution introduced to the House by Representative Alexandria Ocasio-Cortez of New York. Most of all, they want to join voices with the youth around the world to raise awareness that climate change is real and can’t be ignored. “We only have 11 years until climate change is irreversible,” Bruck added. “I’ll be 27 then. I want to be getting a master's in sociology then, worrying about my education, not survival.”

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The San Francisco strike was co-organized by another member of Youth vs. Apocalypse, 15-year-old high school sophomore Nadja Goldberg. She and the rest of the team have had to squeeze protest planning into their already full school schedules. “It’s insane. I’ve gone a few nights with not a lot of sleep. Right now it feels like climate activism is my main goal, and school is this hurdle to get over in the process of doing that,” she says.

During late-night video meetings, Goldberg and her friends have planned the event to the last detail, calling Pelosi's office to let her staff know they’d be chanting outside her office and alerting the police that they would be taking the streets without a permit, in the grand tradition of peaceful civic action in San Francisco. They attended training sessions for how to handle worst-case scenarios. They gathered the numbers for lawyers in case things got out of hand.

But they didn’t get out of hand. With signs aloft, Goldberg and her fellow students took over San Francisco’s main downtown thoroughfare, Market Street, and walked while banging on drums and leading chants. “Walk slow, walk safe, walk powerfully,” 15-year-old Hannah yelled into a microphone at the front of the crowd. The police did arrive, but only to keep the kids safe. Adult advocates watched on the sidelines—teachers came with their fourth-grade students, parents escorted their kids who were too young to take public transit alone. Members of the nonprofit climate activist group Sunrise Movement wore yellow vests, helped direct traffic, and observed the students, but didn’t take the lead.

At strikes elsewhere in the US and the globe, the adults were there to listen, not speak. What they heard from the kids was the repeated warning that if climate change isn’t reversed by 2030, there’s no turning back. Early Friday, before New York City’s strike began, organizer Villasenor addressed the UN, telling the assembled world leaders: “Today, you are hearing from children all over the world as we strike for our futures. We are telling you we are trapped, and the time has come for you to turn the furnace off and save us all.”