On November 13, 2018, just days after Democrats reclaimed the House of Representatives, dozens of young activists filed silently into Representative Nancy Pelosi’s office on Capitol Hill. Some sat down along the walls of the office, unfurling banners and forming a circle. Others stood in the center and told their stories. A teenage woman from Northern California began, “There were fires at my school. There was ash falling from the sky for a week.” She and her companions in the Cannon Office Building that day carried manila envelopes containing pictures of the people and places in their lives that climate change would destroy—or already had. On one side of the envelopes were the words “Dear Democrats”; on the other, “What Is Your Plan?” After some time, they began to sing—the protest songs of another generation, like “Which Side Are You On?,” and new ones they’d written themselves, about waters rising up and people rising, too. Their voices echoed down the marble halls.

Within weeks, their ambitious demand for a “Green New Deal” to decarbonize the U.S. economy by 2030 and provide a green job to anyone who wants one was on the lips of every congressional staffer, cable news reporter, and progressive candidate for president in the country. Reporting for Vox in late 2018, veteran environmental writer David Roberts described the astonishment of longtime climate wonks and advocates at the sudden ubiquity of the Green New Deal, the sense among those involved that they had “caught a tiger by the tail.”

Achieving this sort of moment, in which the horizons of political possibility expand with an almost audible snap, is what every social movement hopes to accomplish. But only some do. Silicon Valley has been working for the military since the start. Why are tech workers only now forcing some firms to turn down DoD contracts? Jim Crow was the law of the land for 80 years, undergirding the architecture of social and political life in the American South. How did organizers with SNCC, SCLC, CORE, and others manage to topple it in less than a decade? How did ACT UP change the public perception of AIDS from a disease whose victims were scorned and blamed for their suffering to a public health crisis demanding federal intervention? And why, despite over a decade of increasingly deadly hurricanes, droughts, monsoons, and heat waves, has no movement arisen with sufficient power to topple the cabal of fossil fuel billionaires who are largely responsible for the climate crisis?

“The whirlwind” evokes something visceral about what it feels like to be involved in a wave of political upheaval. It disorients, defies gravity, upends things and leaves them in a new place.

Alexandria Ocasio-Cortez gets much of the credit for bringing the Green New Deal into the mainstream. She visited Pelosi’s office during the sit-in, and in the following weeks, her staff collaborated with Justice Democrats, the progressive electoral outfit started by veterans of the Bernie Sanders campaign, to draft a policy proposal for a GND. But the plan truly owes its swift rise to a grassroots climate organization called Sunrise Movement, launched a year and a half ago by twelve young organizers—refugees from more mainstream climate organizations like Sierra Club and 350.org, and veterans of fossil fuel divestment and anti-pipeline campaigns.

Unlike more traditional environmental groups—which have long pushed for incremental, market-based reforms to mitigate the crisis—Sunrise doesn’t intend to appeal to elite opinion or sway elite institutions. Defeating climate change, Sunrise’s leaders have come to believe, will require a massive reordering of the U.S. economy—away from free-market fundamentalism and toward something fairer and more democratic. If they succeed, they may not only dramatically shift the politics of climate change, but also provide a new model for grassroots organizing in America.