Hundreds of thousands of people from across the city and around the world marched through the streets of Manhattan on Sunday to raise awareness of global warming.

The People's Climate March, billed by its organizers as the largest event of its kind, drew former U.S. Vice President and Nobel Peace Prize winner Al Gore, New York City Mayor Bill de Blasio, and performing artists Leonardo DiCaprio, Mark Ruffalo and Sting.

Organizers...