The sweeping legislation unveiled in the U.S. Senate today aims to curb climate change, arguably one of the biggest tasks ever undertaken on this planet. But it’s a bill that runs to more than 800 pages, and hidden in its folds is a provision that could turn a noted symbol of New York City — the yellow taxicab — green.

And it wouldn’t just be in New York. Boston, San Francisco, Seattle and other major U.S. cities would be able to create taxi fleets made up entirely of hybrid vehicles under the proposed Green Taxis Act of 2009.

Offered by Sen. Kirsten Gillibrand, who now fills Hillary Clinton’s former seat in the Senate, the measure aims to cut greenhouse gas emissions by more than 296,000 tons in New York City alone, which its sponsors say would be like taking some 35,000 cars off the road and save drivers $4,500 annually in gas costs.

“By creating an all hybrid taxi fleet, we can improve air quality and lower carbon emissions,” Gillibrand said in a statement. “As a mother with an asthmatic child, I believe this is a win-win for our children and our efforts to combat climate change.”

That has to be a good thing, and it’s not exactly unheard of. A quick search for “green taxi” turns up nearly 70,000 hits. But will New Yorkers say “Fuhgeddaboutit”? Will the Taxi and Limousine Commission oppose it? WIll preservationists balk at changing what has become a durable talisman of life in the Big Apple? Or will New York residents (and other residents of other cities where this law could apply) embrace their inner environmentalists?