Organizers of the People’s Climate March expect more than 100,000 people to take part in the event in New York on Sunday Sept. 21.

Scheduled to take place two days before the city hosts the U.N. Climate Summit, the event is being touted as the largest climate march in history.

“We’re expecting upwards of 100,000 people,” Hoda Baraka, a spokeswoman for 350.org., one of the march’s organizers, told FoxNews.com. Baraka noted that almost 100,000 people attended a similar march at the U.N. Climate Change Conference in Copenhagen in 2009.

U.N. Secretary General Ban Ki-Moon will take part in the New York march, as will billionaire environmentalist Tom Steyer.

“It’s not just mobilizing in New York – we have over 2,000 events scheduled worldwide,” said Baraka. “So many people are mobilizing, not just in New York, but all over the world – it’s bringing together people from all different walks of life, all of them united in a call for action for climate change.”

However, Dan Simmons, vice president for policy at the Institute for Energy Research, a Washington, D.C.-based free market think tank, told FoxNews.com that environmental campaigners are keen to avoid a repeat of the Copenhagen Summit, which was seen as falling short of its goals.

“Environmental activists are pulling out all the stops to try and get people to this march, because, I think, the president was embarrassed five years ago by the lack of public support for his position to limit greenhouse gas,” he said.

The Climate Summit on Sept. 23, which will be attended by President Obama, is timed to coincide with the start of a new U.N. General Assembly session. Advocates for a climate agreement are hoping that the event will breathe new life into the U.N.’s green agenda.

The U.N. has suffered a number of blows in its push for a climate agreement. Australia’s new government, for example, recently repealed its two-year old national carbon tax, and countries such as Canada, Russia, and Japan have refused to sign on for an extension to the Kyoto Protocol to combat greenhouse gases.

Earlier this week, the U.S. outlined its plan for a possible global climate agreement.

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