SUNDAY TIMES WEB DESK:Under sunny skies, activists sang songs or held signs that read “There is no Planet B” and “Extinction is forever” at some of the capital’s most iconic locations. Roadblocks will continue night and day at each site and the demonstrators say the protests could last at least a week.

The protests are being led by the British climate group Extinction Rebellion and will involve demonstrations in 33 countries around the world over the coming days.

“I realized that signing petitions and writing letters was not going to be enough. Real action is needed,” said Diana McCann, 66, a retired wine trader from south London, holding a banner in the middle of a traffic-free road. “It’s like a world war. We have to go on to a war footing.”