Around 150 activists have been arrested in London as Extinction Rebellion kicks off two-weeks of protest.
The group - also known as XR - says it is protesting against the government's 'lack of action' on climate change. Describing itself as a 'non-violent civil disobedience activist movement', it wants to 'peacefully occupy the centres of power and shut them down' in a bid to bring attention to its cause.
Campaigners are also demonstrating simultaneously in other cities across the world, including Berlin, New York, and Amsterdam.
XR has three demands - firstly, it wants the government to declare a climate emergency, and secondly, the UK to legally commit to reducing carbon emissions to net zero by 2025.
Thirdly, it says these changes must be overseen by a specially-formed citizens' assembly.
Animal Rebellion (AR), which describes itself as a 'mass volunteer movement using nonviolent civil disobedience to end the animal agriculture industries' is also protesting in solidarity with XR over the two weeks.
This morning, campaigners gathered in Russell Square before marching to the UK's largest meat market, Smithfield, where it has opened a fruit and vegetable stall - a symbolic reference to what AR says is a necessary shift to a plant-based diet.
Changing the system
Leading environmental journalist George Monbiot opened the stall, giving a speech, in which he said we can no longer pretend that tweaking the existing system will save the planet. "We have to change the system," he said.
"We have to change the destruction animal-eating system we have at the moment for another one."