When: September 21, 2014, beginning at 11:30am

Where: Starts at Columbus Circle, ends at 11th Ave. between 34th St. & 38th sts.

Environmentalists are revving up to convene in Manhattan for what's being billed as the "largest demonstration for climate change in history." Set to take place on September 21, 2014, the People’s Climate March is timed to precede an emergency Climate Summit at the United Nations (on September 23), which will be attended by President Obama and worldwide leaders.

March organizers are gunning for the demonstration to demand action from the summit participants, as they gather to negotiate a resolution to the growing global climate crisis.

The well-organized march is being helmed by thousands of volunteers and a strong online presence, which is helping to coordinate transportation, lodging, volunteers, and general event logistics. There's no single coalition in charge, but, rather, the march is unfolding as a collaboration between numerous groups and individuals with complementary ideas.

Participants who have signed up to date include more than 45 labor unions, New York-area community organizations, schools, environmental groups, faith organizations, and more. You can sign up to march with like-minded groups, by scrolling through the posted participants on the People's Climate March's website.

With estimated turnout predictions of up to 100,000 participants, marchers are encouraged to bring their own signs and banners, or to download supporting materials to better demonstrate their position from the official website.

Artists and activists are currently busily crafting floats, banners, and sculptures in preparation for the September 21st event.

The march will follow a path from the assembly point just north of Columbus Circle, following 59th Street to 6th Avenue and on to 42nd Street, ending on 11th Avenue, between 34th and 38th streets. The route passes by major attractions like Rockefeller Center and Times Square en route, which will help ensure the attention of an increased number of city visitors and passers-by.

In buildup to the event, be on the lookout for a widespread ad campaign on city subways; some 10 percent of NYC subway ads will serve to promote the event, as per global campaigning group Avaaz.

To date, some 950 organizations around the globe have signed up in support of the march, representing an estimated 100 million people worldwide. Coordinated solidarity events will be organized outside of NYC, too, with major demonstrations planned in New Delhi; Melbourne, Australia; London; Berlin: Paris; and more.

The U.N. Climate Summit this September marks the start of a round of international negotiations, with aims of reaching a global climate deal that would serve to dramatically reduce global warming pollution. Subsequent meetings will follow in Lima, Peru; NYC (again, in September 2015); and finally in Paris in December 2015, where the U.N. aims to ratify an international climate treaty. Hopefully, your voice here in Manhattan on September 21 will help that happen. I'll see you there! peoplesclimate.org/march