They've blocked bridges, glued themselves to the gates of Downing Street, and closed roads, all in the name of stopping climate change.

On Friday they protested outside several BBC offices in the UK, demanding that the corporation make climate change and environmental issues its top priority - in both editorial coverage and corporate management.

Extinction Rebellion's aims include net zero carbon emissions by 2025 and a national Citizen's Assembly to oversee environment work.

The campaign was launched earlier this year by Rising Up, a network of activists including former members of groups ranging from Earth First! environmentalists to the anti-corporate Occupy movement formed during the global financial crisis.

Despite criticism from some that their demands are unrealistic and their methods annoying, support has grown, with 100 academics - including the former Archbishop of Canterbury, Dr Rowan Williams - giving their backing.

So what's the movement all about?

This video was originally published 20 December 2018.