Police officers arrest protesters in London, Britain, Oct. 7, 2019. London police confirmed 21 arrests so far in the central part of the British capital on Monday morning at the start of two weeks of protests by environmental campaigners. (Photo by Ray Tang/Xinhua)

A protester (L) talks with a police officer during a demonstration in London, Britain, Oct. 7, 2019. London police confirmed 21 arrests so far in the central part of the British capital on Monday morning at the start of two weeks of protests by environmental campaigners. (Photo by Ray Tang/Xinhua)

Environmental activists stage a protest in London, Britain, Oct. 7, 2019. London police confirmed 21 arrests so far in the central part of the British capital on Monday morning at the start of two weeks of protests by environmental campaigners. (Photo by Ray Tang/Xinhua)

Police officers arrest a protester in London, Britain, Oct. 7, 2019. London police confirmed 21 arrests so far in the central part of the British capital on Monday morning at the start of two weeks of protests by environmental campaigners. (Photo by Ray Tang/Xinhua)

Police officers try to cut free a protester from an abandoned car in London, Britain, Oct. 7, 2019. London police confirmed 21 arrests so far in the central part of the British capital on Monday morning at the start of two weeks of protests by environmental campaigners. (Photo by Ray Tang/Xinhua)Police officers try to cut free a protester from an abandoned car in London, Britain, Oct. 7, 2019. London police confirmed 21 arrests so far in the central part of the British capital on Monday morning at the start of two weeks of protests by environmental campaigners. (Photo by Ray Tang/Xinhua)