On Sunday, just two days before the UN Climate Summit to address the very real problems being created by climate change, roughly 400,000 people (four times the expected turnout) swarmed the streets of New York City to demand meaningful action from world leaders. And, as someone who was there, I can say it was pretty incredible. Leonardo DiCaprio, Jane Goodall, Mark Ruffalo, New York City Mayor Bill de Blasio, Al Gore, and UN Secretary-General Ban Ki-moon marched alongside a sea of protestors in Manhattan, who held up signs that said things like "Don't Be Frackin' Crazy" and "#DisruptDenial." Despite the serious nature of the issue at hand, the mood of the march was joyful and the crowd seemed to swell with a sense of history-in-the-making. With more than 2,600 related events in over 150 countries, it was by far the largest global call for climate action ever. May Boeve, executive director of march's primary organizer 350.org, said in a press release: "Today, civil society acted at a scale that outdid even our own wildest expectations. Tomorrow, we expect our political leaders to do the same." Check out a few of our favorite signs from the march: