On Saturday, over 300,000 people marched in Manhattan take placed in the NYC People’s Climate March to peacefully protest and advocate environmentalism. Hundreds of different activist groups and organizations participated in the march. The march took place to to gain momentum for the UN Climate Summit happening today, in which United Nations Secretary General Ban Ki-moon is meeting with world leaders in hopes of advancing climate action and ambition.

Ban Ki-moon attended the march, along with other notable figures including Leonardo DiCaprio, former Vice-President Al Gore, Mark Ruffalo, and Joseph Gordon-Levitt. Below is an interview with actor Joseph Gordon-Levitt, who calls climate change the “great threat.”

Filmed and Edited by Lauren Clemence