NEW YORK -- Preparations for a large climate-change demonstration in New York City have reached a fever pitch, CBS New York reports.

At a warehouse in the Bushwick neighborhood of Brooklyn, artists made banners and floats for Sunday's event that's called the People's Climate March.

"This is a little bit unusual," organizer Rachel Schragis said. "I don't think it's ever been done at this scale before."

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Organizers are saying that they expect more than 100,000 people to participate.

The march comes ahead a U.N. summit on climate change, where more than 120 world leaders in New York for the annual U.N. General Assembly meeting will meet on the issue. President Obama is expected to speak at Tuesday's summit.

U.N. Secretary-General Ban Ki-moon is "excited to link arms" with the protesters Sunday, spokesman Stephane Dujarric said in an email to CBS News.

"It's clear that climate change is no longer a problem for the future. We can no longer delay action - if we delay we will pay," Dujarric said. "These marches show world leaders that people want action on climate change now."

Schragis said artists are aimed at turning the march into a visual spectacle, "making a pageant or parade."

Joel Stein of Brooklyn donated his time to the march's preparations.

"I'm concerned about the future," he said. "I'm concerned about the future that my children will inherit, that my family will inherit."

"You are not doing enough," Schragis said of the message she wants to send to world leaders. "We demand bold, global action on climate change."

Protesters are expected to wind their way through midtown Manhattan.

"The debate is over," Schragis said. "We see by the outpouring and the variety of people who are so excited about this march, people do care. They get it. They're concerned, and they want to know what to do."