Berkeley, California - Introducing Tom Steyer, the man newspapers like to call “the billionaire environmentalist,” Jennifer Granholm praised him Wednesday night at International House as a “great warrior for our planet.”

In style, at least, Steyer seemed a remarkably soft-spoken warrior during a 25-minute talk - followed by a question-and-answer session with Granholm, an adjunct professor at the Goldman School of Public Policy and former Michigan governor - as the school’s Michael Nacht Distinguished Lecturer in Politics and Public Policy. Yet while his tone was more in keeping with the boardroom than the barricades, he described the fight to curb climate change as “the generational challenge,” comparing it to his father’s generation’s experience in World War II.

“I honestly believe that in 50 years, 100 years, 200 years, the way that our society will be judged is on whether we can rise to the challenge, and I’m sure we will,” said Steyer, who left a lucrative career as a hedge fund manager in 2012 to work full-time on environmental issues. He has taken investor Warren Buffett’s “giving pledge” — a promise to donate the majority of his wealth to philanthropy — and, through his advocacy group NextGen Climate, funneled an estimated $57 million into the 2014 elections on behalf of Democratic candidates.

In the Chevron Auditorium, dressed in jeans and a shirt and tie, Steyer focused less on money in politics than on the importance of voting, and blamed the weakest Democratic turnout since 1942 — and the “shockingly low” turnout of millennials — for the party’s dismal showing at both the federal and state levels in 2014. “Opinions are nice,” he said, “but votes change our country.”

“The science on [climate change] is pretty much settled,” Steyer said, but noted “the political issue is very, very far from settled.”

Without citing the Koch brothers by name, he reminded his listeners that “very large carbon polluters have promised to put up $1 billion” to get oil-friendly candidates elected in 2016. Nonetheless, he expressed confidence that supporters of alternative, carbon-neutral energy sources could still win at the ballot box.

“The thing that politicians respond to is votes,” Steyer said. “Even the money is just a means to get votes.”

“There are more climate deniers in the United States of America than there are in the rest of the world combined,” he said. But he said the past two years have seen support growing for action to combat climate change among the electorate, the business world and even Republican voters, if not the party’s leaders.

As for policy solutions, Steyer focused mainly on energy efficiency, which he called “just good business,” and a carbon tax, “the simplest, best way of letting the market adjust for pollution.”

And he pointed to California as a living example that “this is not a choice between having a healthy environment and having a healthy economy.”