LONDON — Earlier this year, a little-known environmental group, Extinction Rebellion, brought London to a standstill. They’re now aiming to paralyze at least four other European capitals next week while holding other protests in the United States and more than 60 other countries worldwide to demand immediate, sweeping action against climate change.

The group officially launched last October with a small protest outside Parliament featuring a speech from Swedish teenage activist Greta Thunberg. But Extinction Rebellion really won worldwide attention this April when eye-catching protests brought London to a crawl for almost two weeks. Activists occupied major traffic hubs around the clock, superglued their bodies to buildings and trains, and marooned a full-sized pink boat in the middle of a major business district.

The Extinction Rebellion movement has been the raucous sibling to Greta Thunberg’s school climate strikes, turbocharging the politics of climate change across Europe and drawing growing numbers around the world. The April protests ended with more than 1,000 arrests, and, despite scoffs from conservatives and stern warnings from law enforcement officials, the group's strategy worked. Within weeks, the House of Commons adopted a resolution declaring a climate “emergency.” The action was symbolic — and far short of the dramatic pledge to cut carbon emissions that Extinction Rebellion has demanded — but it was a huge success just to get climate change on the agenda at a time the government was near collapse over the Brexit impasse. Small-scale protests have occurred worldwide under the Extinction Rebellion banner regularly.

Next Monday marks the official start of what Extinction Rebellion is calling the “International Rebellion.” It likely won’t draw the hundreds of thousands of people who joined September’s climate strikes led by Thunberg’s Fridays for Future movement. But Extinction Rebellion works on a different model of change. Instead of getting everyone to join them for marches, its organizers are focused on mobilizing a passionate minority that is willing to engage in nonviolent direct action, putting their bodies on the line to halt business as usual until their demands are met.

“Even though there were only a few of us, we couldn’t deal with the reality that humanity was racing towards the precipice of extinction and doing fuck all about it. This is our chance to really act differently,” said Robin Boardman, a 21-year-old who dropped out of college to help start Extinction Rebellion, during a Thursday press conference in London. “I am prepared to go out on the streets and do everything I can to create that change. I’m prepared to go to jail if it means it.”

The British chapter kicked off the rebellion a little early, spraying fake blood on the Treasury Ministry building in London from a decommissioned fire truck Thursday morning. (Protesters lost control of the hose during the stunt, drenching several bystanders.)