By Mari Kasanuki
Updated Sep 22, 2014 @ 9:21 am
People's Climate Change march
Credit: Nancy Rivera/ACE/

Leonardo DiCaprio, Edward Norton, Mark Ruffalo, and Evangeline Lilly were among the stars who came out on Sunday to join the People's Climate Change march in New York City. An estimated 400,000 people reportedly took to the streets of Midtown Manhattan in a demonstration to promote climate-change action that became one of the largest environmental marches in history.

Related demonstrations took place across the globe, from Paris to Melbourne, Australia. and Emma Thompson and Cara Delevingne were among the protestors in London. Delevingne participated while dressed in an animal costume, and captioned this Instagram shot, "WE ARE ONE!!":

The events come in advance of Tuesday's United Nations Climate Summit in New York, where global leaders will gather to discuss climate change. Discover more stars who are championing causes here, plus see more images from the march below!