Tom Steyer isn’t your average California tree hugger. The former hedge fund manager—number 1,121 on Forbes’ wealthiest people list, with $1.61 billion—was once best known for turning $15 million into $30 billion in about two decades.

But then he went hiking. Steyer and environmental activist and author Bill McKibben spent a day trudging through the Adirondacks. Not long after, Steyer parted ways with the leadership of his company and his oil and gas investments, began to fight the Keystone XL pipeline, and then reinvented himself as a one-man superfund for climate causes. His organization, NextGen Climate, has spent $170 million over the past four years advocating for policies and politicians that help the environment and advance renewable energy.

It’s an uphill battle. Steyer was the largest single donor on either side of the 2016 election—$86 million of his own money. Yet climate change skeptics rule the federal government and many statehouses. Somehow, though, Steyer isn’t acting like a loser. Since November he’s become an even more vocal representative of the nearly two-thirds of Americans who do think human-caused climate change is a real problem. He talked to WIRED about California’s role in science, his own po­litical ambitions (“governor” has a better ring to it than “former hedge fund manager,” right?), and whether Donald Trump could ever possibly, conceivably help save the planet.

wired: So Keystone XL has been revived, the Clean Power Plan is in peril, and the former CEO of Exxon is our secretary of state. How are you?

Steyer: I know there are five stages of grief, but my parents raised me to pull up my socks when times get tough. So I really never had the luxury of feeling bad, because right after the election I felt like we needed to figure this thing out.

What is NextGen going to do?

We have been cosponsoring marches with immigrants’ and women’s rights groups. We’ve been running ads against Trump’s nominees and policy positions. And we’ve been organizing resistance activities on the college campuses where we established ourselves during the campaign. We will continue to go on the offensive each time the administration attempts to derail global actions to stop climate change.

During the confirmation hearings for Rex Tillerson, Scott Pruitt, and others, you guys took out attack ads. What’s your goal?

Those guys disagree with us on almost every point. One of the things we strongly believe—and Tillerson was a perfect example—is that the people Trump nominated consistently put corporate interests ahead of American interests. We feel it’s important to get citizens to be reminded of this common thread: that the new administration doesn’t hate working against climate change, they don’t hate science—they just love oil and gas profits.

There’s a wide swath of rural Americans who are happy and hopeful for Trump. Are you reaching out to them?

After the election, the first thing I wanted to know was how our voter registration work on 370 campuses across the country affected turnout. We monitored 12 precincts where there were a lot of millennials and saw that voter turnout was up overall. And turns out, we did do well at rural schools. What we are still trying to figure out is whether that turnout voted Republican or Democrat. That is, if those new voters brought our messaging about politicians who supported climate action to the voting booth.

The Evolution of a Man ———————–

From Wall Street to the Adirondacks, billionaire Tom Steyer took an unusual path to becoming the nation’s leading climate change activist. —Lexi Pandell

1986

An alumnus of Morgan Stanley and Goldman Sachs, Steyer moves to San Francisco and starts the investment firm Farallon Capital with $15 million.

2003

Steyer becomes more involved in California politics and briefly considers running for governor in the wake of the Gray Davis recall.

2004

Students at Yale and Stanford (Steyer’s alma maters) criticize the universities for investing in Farallon, which they say funds antilabor and antienvironment companies. Steyer takes note.

2006

Twenty years after its founding, Farallon Capital is worth $30 billion.

2011

A year after he and his wife, Kat Taylor (pictured, above, in the mid-’90s), sign the Giving Pledge, Steyer joins the board of Next Generation, an organization for children’s issues and climate change.

2012

After reading an article by author Bill McKibben, Steyer invites the writer on a hike in the Adirondacks. Steyer comes out of the wilderness ready to advocate for alternative energy.

2013

Steyer founds NextGen Climate, an environmental advocacy nonprofit and political action committee.

2016

NextGen Climate puts up $95 million for candidates, voter engagement, and more. Steyer spends nearly $86 million himself.

photograph courtesy of the Steyer family

Given what you know about how policy moves markets, what will we give up when Trump pulls the US out of the Paris agreement?

I was in business for 30 years, and my experience is that the best way to operate is to work fairly and closely with partners over a long period of time. The most expensive way to do business is to do it deal by deal, each of which is highly contentious. If deal by deal is the model, where instead of partners or allies we have counterparts and competitors, that is very expensive, difficult, and dangerous. OK, so look at the Paris agreement: It’s going to force the developed world to change its energy sources. That means the US could be the leader in developing renewable technology for more than a billion people—a huge incoming market—who don’t have electricity at all.

The Paris agreement was a great achievement of American leadership. So the idea that we’re going to walk away and give up leadership of 194 countries, and walk away from our position as a leader in the world for the past 100 years, will be an incredibly expensive and dumb thing to do.

Are there any Republican climate leaders?

You know, we all act like it is an incredible triumph if a Republican shows the remotest respect for climate science. When Kelly Ayotte—who has a dismal 35 percent rating from the League of Conservation Voters—voted for the Clean Power Plan, a lot of people said, “Oh, she’s really an environmentalist.” But that’s ignoring her record and the reason why it’s so hard for her and other Republicans to stand up for the environment in this political climate, because they have to stand up to the fossil fuel industry. I think there are a lot of Republicans who know the truth and would like to do the right thing but don’t understand how.

Solar and wind energy costs have been coming down for decades. Why aren’t they replacing fossil fuels faster?

There are a lot of subsidies for oil and gas, things like tax breaks and access to markets. That’s partly because there’s a lot of volatility in the oil and gas markets. Fossil fuels are raw materials that have to be extracted and processed. Wind and solar energy are different. The only costs associated with them are technological. WIRED readers should be familiar with the idea that technology gets better and cheaper every year. That’s not true about fossil fuels. The techniques we use to withdraw them might get better every year, but the price has actually risen over time. If you take away subsidies from fossil fuels, wind and solar are actually cheaper.

You believe businesses can provide solutions to climate change but only with the right government policies. Is that era over?

Well, most of the energy regulation in the US comes from the state level, which lets states like California pursue more ambitious emissions regulations. It also lets states with lots of renewable energy coordinate to share it when needed, but federal regulations would help more.

The issue is going to be, to an extent, what the new administration will do to subsidize fossil fuels—how they can make dirtier fuel, which is more expensive, more attractive. Maybe that means leasing public lands at low prices. But the only thing they can really do to ensure long-term drilling is put in infrastructure, like pipelines.

Do you think there is any chance for Trump to not be awful for climate?

[Long pause.] I don’t think there’s any chance that Trump is going to step up and do the right thing out of the conviction that it’s the right thing to do. But, you know, you can’t really say what’s going to happen, because the world does tend to surprise us. If you didn’t learn that in 2016, then you weren’t paying attention.

Can California’s politicians really create a bulwark against Trump?

The administration has said they’re going to go after their political opponents. California embodies that opponent. Taking money away from health care, in the form of the Medicaid expansion—that would be more than $15 billion from California’s budget. Consider that the state’s general fund budget is about $120 billion. They are also going after cities that resist their deportation efforts. They’re talking about withholding money from schools. This is gigantic and very, very threatening. If you talk about trying to stand up as best we can for the people of California, and by doing so put forward a different image of what the true values of Americans are, just be aware, it ain’t cheap. My point is, this is not a theoretical problem for us.

How potent is the state’s ability to resist?

Financing that opposition will be tricky. First, the California budget is leveraged really highly to the personal income and capital gains of the richest Californians. That means it is super volatile, because incomes go up and down much more often than property values, which is how most states finance themselves. What’s worse is that the budget is also highly leveraged to the stock market. So when tech companies are going public and things are happening, then that income for the employees who benefit gets taxed in California like regular income. If there are no tech IPOs, the tech sector isn’t doing well, so there aren’t a lot of stock profits—equity profits—from those companies, and that hits the revenue line of the California state budget [claps loudly] super hard. You may have also noticed that we have had a bull market for the past six years.

In January, in an op-ed for The Sacramento Bee, you wrote about creating “the broadest coalition possible, one that embraces our shared values and delivers on the promise of a better future for all Americans.” You even echo Obama’s “Let’s get to work.”

Maybe he stole that from me!

Well, it reads like you are a guy getting ready to run for office.

[Slaps table.] Well, our mission statement is: “Act politically to prevent climate disaster and promote prosperity for every American.” So are we broadening our message? That’s always been our message. Whatever I do, and I honestly don’t know what it is, will be consistent with that effort.

*Nick Stockton (@stocktonsays) is a staff writer on the science desk at *WIRED.

This article appears in the April issue. Subscribe now.