Demonstrators have blocked the usually bustling Oxford Circus intersection, one of five London landmarks targeted by environmental campaigners as part of the action on Monday.
Some protesters dressed in yellow paper crowns were lying in the street in a "die-in," their arms linked through tubes. Nearby, others stood atop a pink painted sailboat emblazoned with the message, "Tell the truth," with a flag bearing Extinction Rebellion's hourglass logo.
Mark Ovland, one of the protesters glued to the pink boat at Oxford Circus, said he and others were trying to bring massive disruption to transport in London to "gain attention to what is the biggest crisis facing humanity at the moment."
"For 30 years people have known the signs of what's happening with the climate, with the ecological crisis, nothing's been done. We've tried writing letters, we've tried voting with our feet, we've tried campaigning in all the usual institutional ways, nothing's worked, emissions keep going up year on year and so this is the last thing we can think of," Ovland told CNN. "We don't want to disrupt people, but we think this must surely get attention. We need to do this."