The polar bear of Wall Street protested the banks he says drive climate change. (Danielle Paquette/The Washington Post)

NEW YORK — He came from California, this activist in the polar bear suit. The Manhattan air Monday evening was cool, distinctly fall, so he did not break (an uncomfortable) sweat inside the polyester fur. He could see through a strip of white mesh, hidden below a pair of beady black eyes — literally, they were black beads — and a plastic snout glazed to appear moist. His paws clutched a sign: CLIMATE ACTION NOW.

The polar bear of Wall Street, an overnight social media phenomenon, is 51-year-old Peter Galvin, a founder of the Center for Biological Diversity in Tucson, Ariz., one of the more strident environmental groups in the country. He became a brief social-media sensation on Monday, at the more confrontational of the two climate change protests that filled the streets of New York in the days before international leaders met to pledge action to curb global warming.

His costume and his tactics were a throwback to years of demonstrations that, for activists, have yielded disappointingly few results. Gavin was far from the first man to protest global warming in polar bear garb. Another was arrested five years ago in Copenhagen during a similar march, which coincided with a round of United Nations climate talks.

A longtime activist, Galvin embodies this spirit of seasoned protester, a die-hard environmentalist who feels at home bashing capitalism mere yards from its symbolic home, the New York Stock Exchange. He’s not like the newbies, the thousands of first-time protesters who rolled legal-incident-free through Manhattan on Sunday in what was called the largest climate march in history. Galvin knows what he’s doing, the risks of defying law enforcement. And he knows you’ll likely tweet about it.

He was a popular protester at Flood Wall Street, which aimed to interrupt and shame businesses that organizers say drive climate change. Protesters, who blocked traffic near the stock exchange from sunrise to sundown, wanted to raise awareness about the link between carbon emissions, global warming and the big banks they say fund global destruction. Call it an environmental update to Occupy Wall Street, which started three years ago at a Manhattan park to denounce big banking practices. Flood Wall Street followed Sunday’s People’s Climate March, which drew more than 300,000 protesters to Central Park.

Galvin lives in Shelter Cove, Calif. and once worked as a government contract wildlife researcher. He wears the polar bear suit to provoke discussion. (And because the kids love it.) “I want people to think of climate change in a different way,” he said. “We’re in a crisis, and our economy is driving it. We’re all in danger.” Wall Street, he said, needs to invest in renewable energy — the kind that doesn’t “destroy our planet.” After police ordered protesters to disperse Monday, the polar bear parked his fuzzy behind at the intersection of Broadway and Wall Street, a block from the Stock Exchange. He was among about 100 protesters arrested. Twitter noticed.