To underscore the planetary emergency and denounce the U.K. government's inaction on the climate crisis, a new group calling itself Extinction Rebellion rallied over 1,000 people to block Parliament Square in London on Wednesday. The direct action marks the launch of a mass civil disobedience campaign, with the group issuing a "Declaration of Rebellion" against the government because the activists "refuse to bequeath a dying planet to future generations by failing to act now."