Central London traffic has been disrupted by protesters who blocked off major hotspots as part of a "rebellion day".
Extinction Rebellion protestors blocked traffic at Lambeth, Tower and Vauxhall bridges, Elephant and Castle and Earls Court.
Organisers said 100 people gathered in central London to demand the government take greater action on climate change.
The "road-blocking protests" will continue on Thursday and Friday.
Large groups of people holding banners began congregating at the "central hotspots" from 07:00 GMT before blocking off the traffic.
Some frustrated motorists shouted abuse at the protestors, including comedian and presenter Jim Davidson who yelled to the police: "Why aren't you moving them? Climate change? Don't they like being warmer?"
Organisers said the plan was to cause major disruption with a number of small teams of 20 or so activists moving around London.
"These disruptive protests aim to cause gridlock across the capital, highlighting the impending economic and environmental breakdown we face if the government fails to act now", a spokesman said.
"Extinction Rebellion demands the government tell the truth the about the climate and ecological emergency."
On 12 November, activists blockaded the UK's energy department by chaining themselves together on the pavement.
Two days later protesters glued themselves to the gates of Downing Street.
Over two weeks, more than 60 arrests were made over acts of civil disobedience with some activists arrested more than once.