Environmental activists called for people to gather on the streets of their cities on Sunday to march in a coordinated worldwide protest. More than 300,000 people, including celebrities and politicians, descended on Manhattan for the People's Climate March right before the United Nations Climate Summit in New York City. http://www.mashable.com LIKE us on FACEBOOK: http://facebook.com/mashable.video FOLLOW us on TWITTER: http://twitter.com/mashablevideo FOLLOW us on TUMBLR: http://mashable.tumblr.com FOLLOW our INSTAGRAM: http://instagram.com/mashable JOIN our circle on GOOGLE PLUS: http://plus.google.com/+Mashable Subscribe!: http://bit.ly/1ko5eNd Mashable is the leading independent news site for all things tech, social media, and internet culture. http://www.youtube.com/mashable