London -- Climate change protesters packed up their camp in London on Thursday night after nearly two weeks of demonstrations that resulted in more than 1,000 arrests across the United Kingdom. But their fight isn't over. The group behind the protests says they are moving on to the next phase of their "rebellion."

Activists camped on the edge of London's Hyde Park for 10 days as they took action across the U.K. capital, including gluing themselves to trains, blocking major intersections and shutting down shopping areas.

"I don't go to many marches, this isn't really normal for me, but this one is the most important thing that anyone could ever do," a woman carrying an infant told CBS News as she marched past Buckingham Palace on Tuesday.

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The group behind the demonstrations, Extinction Rebellion, operates out of an upscale office building in central London. Organizers say they use the space rent-free, because the corporate landlord is sympathetic to their cause.

Volunteers work on laptops, and signs and fliers are scattered around. The symbol of the group is graffitied over nearly every wall.

"I think about how to effectively change society in a crisis. That's why Extinction Rebellion has been successful," said Roger Hallam, who co-founded the group and has been researching effective protest movements for a PhD.

"It's not like three people in a pub going 'let's have a rebellion.' It's like a systematic survey of the academic literature on how societies change radically in a short amount of time," he said. "People need to break the law nonviolently, en masse, preferably in a capital city."

So that's what the group has been doing -- staging almost daily actions that, according to London Mayor Sadiq Khan, have presented a "huge challenge" for London's "over-stretched and under-resourced" police.

But Hallam said straining resources is insignificant compared to the threat posed by climate change. "The theater is on fire," Hallam said.

The group is now planning its next steps.

"The government is guilty of criminal inactivity on climate change. Period," Hallam said.

Climate change activists, dressed in red with white face paint, take part in the Extinction Rebellion protest in London, Britain, April 25, 2019. PETER NICHOLLS/REUTERS

Extinction Rebellion protests over the last two weeks coincided with a visit from 16-year-old climate activist Greta Thunberg, who visited the U.K. on Tuesday to speak to lawmakers. She has led worldwide school strikes to demand aggressive government action on climate change.

"We have not taken to the streets for you to take selfies with us and tell us that you really admire what we do," Thunberg said in Westminster. "We children are doing this to wake the adults up. We children are doing this for you to put your differences aside and start acting as you would in a crisis."