Thousands of New Yorkers gathered near City Hall to demand the city act on climate change hours after activists and protestors took to Paris streets during a United Nations summit.

Among those in front of the building's steps was noted "science guy" Bill Nye, who argued that any investment by New York City to go green would benefit residents in the five boroughs.

RELATED: More than 310,000 attend People's Climate March 

"If we build wind turbines, if we insulate our buildings to make them far more efficient than they are now," Nye said. "If we put solar panels as possible — all those jobs are here … all the jobs would be local." 

March organizer Leslie Cagan said they were looking at the local leaders to mandate that all buildings be converted to be more energy efficient on a faster time table than laid out by the de Blasio administration last year.

"A voluntary program isn't enough," she said. "It will never happen without a [mandatory] plan in place."

Cagan said the local activist movement had faith in the city's elected leaders but that they would hold them accountable for the reforms undertaken and proposals laid out on Sunday.

RELATED: Mayor pledges lower greenhouse gas emissions from New York City by 2050

The coalition of environmental advocates sent a letter to Mayor Bill de Blasio also asking the mayor to commit to off-shore wind energy, expand Bus Rapid Transit, promote community gardens and divest city pensions from all fossil fuels.

The city has been under fire from local community garden groups upset over the administration's consideration of garden sites as possible locations for affordable housing development.

In September, de Blasio proposed divestment of the city's pension funds from coal, and said it would study divestment from all fossil fuels.

Last year, Blasio marched in the People's Climate March in New York City and committed to reducing greenhouse gas emissions by 80 percent in public buildings come 2050, compared to from levels taken in 2005. 

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The administration then also said it would help spur voluntary reductions by private buildings.

Public Advocate Letitia James praised City Hall's commitment to environmental reform but said the city could up the ante.

"We should be aiming to move our city to 100 percent renewable energies by 2030," James said.

This year's climate march coinciding with the Paris summit drew fewer attendees in Manhattan, compared to last year's estimated 400,000.

Still, the hundreds of marchers who circled City Hall park on Sunday were a part of the solution that Nye laid out.

"With improved technology and improved policy in the next two decades," he said, "I strongly believe we can work together to — dare I say it — change the world."