Demonstrations took place around the world to demand action to stop climate change, on the eve of the UN summit in Paris.
More than 2,000 events happened, with tens of thousands beginning the day of protests in Sydney, Australia.
In the French capital, one protest turned violent, leading police to fire tear gas at a large group of demonstrators.
Reports said at least 100 people have been arrested.
Hundreds of pairs of shoes were left on Place de la Republique to remember those left frustrated in their plans to march.
Elsewhere in Europe, some 5,000 people turned out in Madrid, with close to double that in Berlin.
Thousands have gathered for a march in central London, where opposition leader Jeremy Corbyn addressed crowds.
In Sydney, many people carried placards reading “There is no Planet B” and “Solidarity on a global scale”.
About 150 world leaders are due to attend the Paris talks including US President Barack Obama, China’s Xi Jinping, India’s Narendra Modi and Russia’s Vladimir Putin.
