COP21: Rallies call for Paris climate change action Image copyright EPA Image caption The protest in Rio de Janeiro involved plenty of mud Hundreds of thousands of people have marched worldwide to demand action to stop climate change, the day before a UN summit starts in Paris. One campaign group says more than 570,000 protesters took part in marches on all the main continents. Activists want action at the Paris talks to limit the rise in the average global temperature to 2C (3.6F) above pre-industrial levels. In Paris itself, more than 200 demonstrators were arrested after clashes. The day's events In pictures: How eco-activists are mocking brands and leaders Why do two degrees matter? Earlier, a human chain was formed by hundreds linking arms in the French capital along the route of a march that was called off after the 13 November attacks that killed 130 people. A gap in the chain was left in front of the Bataclan concert hall, where 89 people were killed. ...