Over 50,000 campaigners today turned out here in the British capital in one of the largest marches taking place across the world, demanding world leaders to take urgent action to clinch a deal to tackle climate change at the critical UN summit in Paris.
The campaigners marched from Hyde Park to Whitehall in London alongside worldwide demonstrationsahead of the summit.
The Paris conference, known as COP 21, starts tomorrow and will try to craft a long-term deal to limit carbon emissions.
The gathering of 147 heads of state and government is set to be far bigger than the 115 or so who came to Copenhagen in 2009, the last time the world came close to agreeing a long term deal on climate change.
The summit's goal is to limit average global warming to two degrees Celsius over pre-Industrial Revolution levels.
About 2,500 events are taking place around the world this weekend, with London's billed as the largest.
Campaigners from groups such as Greenpeace, Friends of the Earth, Oxfam, ActionAid and the World Wildlife Fund are marching alongside people from around the UK such as a group protesting against fracking in Lancashire.
British fashion designer Vivienne Westwood, actress Vanessa Redgrave, Radiohead singer Thom Yorke, Green MP Caroline Lucas and shadow chancellor John McDonnell are among the other people attending.
"Global warming is at a tipping point. If we go past it we can't stop it. We are there right now. We have to stop it," Westwood said.
Addressing the crowds before the march began, Labour leader Jeremy Corbyn said: "The issues facing the world in Paris this week are pollution, climate change, inequality, environmental refugees, war refugees and resources wars.
"If we are to make a real difference in Paris, all these issues have got to be thought about and addressed," he said.
The 21st session of the Conference of the Parties in Paris will see 10,000 delegates from 195 nations gather to discuss a possible new global deal to reduce greenhouse gas emissions to avoid the threat of dangerous warming due to human activities.
