Earth Day produces many worldwide demonstrations and arrests throughout the week.

The Extinction Rebellion, a U.K.-based grassroots organization, has organized a series of international protests to demand governments take action on climate change. The worldwide protests will continue from April 15 to April 29. Demonstrations have taken place in major cities including London, New York, Paris and Berlin.

Biggest Civil Disobedience Event in London’s Modern History

In London police arrested more than a thousand people since the protests began last week. London Mayor Sadiq Khan expressed concern the demonstrations were taking “a real toll” on London’s police, with around 9,000 officers responding to the civil unrest since April 15.

“I’m extremely concerned about the impact the protests are having on our ability to tackle issues like violent crime if they continue any longer,” said the mayor of London.

Metropolitan Police Commissioner Cressida Dick told the BBC that during her 36-year career she had never seen a single police operation result in so many arrests. Organizers have described the event as “the biggest civil disobedience event in modern British history.”

Oscar-winning actress Emma Thompson joined a rally in Central London on Friday, saying, “It makes me so happy to be able to join you all and to add my voice to the young people here who have inspired a whole new movement.”

Teenage activist Greta Thunberg, well known for her “our house is on fire” speech at the Davos Economic Forum in January, met protesters to cheers on Sunday, April 21, as she told them “we’re making a difference.”

Civil Disruption ‘Could Get Much Worse’

The Extinction Rebellion aims to use non-violent disobedience, and police have confirmed that no officers have been hurt so far.

Despite the nonviolent nature of the demonstrations, critics believe they are over-stretching police time and disrupting public transportation. England’s former Foreign Minister Boris Johnson criticized the protestors, saying the U.K. has been a world leader in reducing carbon emissions and activists should focus their efforts on China, the world’s greatest emitter. Johnson said he was “utterly fed up with being told by nice young people that their opinions are more important than my own.”

An Extinction Rebellion spokesperson told the BBC the civil disruption could get much worse if politicians are unwilling to negotiate. The group is holding a “people’s assembly” to decide what actions they will take in the next week.

Ben Moss, 42, a company director from Bristol and a participant in the protests, spoke to the Guardian about his decision to join the demonstrations.

“It’s drastic times and drastic times need drastic measures. I am taking personal action and personal responsibility for the ecological and climate crisis. I feel really sorry for the inconvenience we are causing, and it is nothing personal, but the inconvenience we will all face if we don’t tackle this will be much, much worse,” said Moss.

Demonstrators in France barred access to bank Societe Generale, the state-owned utility EDP and oil company Total. In the U.S. there are volunteer cleanups throughout the country. In Germany, student activists are demonstrating for a faster exit from coal-fired powerplants.