Amazon CEO Jeff Bezos may very well have fundamentally changed the fight against climate change this week. In an Instagram post Monday, the world’s richest man committed $10 billion of his personal fortune to set up the new Bezos Earth Fund, which would support “scientists, activists, NGOs—any effort that offers a real possibility to help preserve and protect the natural world.” The announcement was light on specifics, and it’s not clear yet how the money will be spent. But climate experts say it’s a massive investment that could help give the warming planet a fighting chance—so long as it isn’t squandered.

Ten billion dollars may not seem like a sizable sum for people in the market to buy a couple of football teams, but it's an almost unfathomable amount of money for climate change research and activism. It dwarfs the $4 billion that 29 philanthropic organizations pledged to fighting climate change in 2018, in what was called the largest investment of its kind at the time. It’s so much money that it will likely be difficult to spend on existing researchers and organizations, as The Atlantic noted. Bezos could fund 2,857 Duke University professors indefinitely, or almost three times the number of tenured professors at Yale, for example.

“It really will shape the whole nature of the climate movement,” says Robert J. Brulle, a professor emeritus at Drexel University studying politics and the environment. “There’s going to be this mad rush of cash.”

Brulle’s research on spending by opponents of the climate movement helps put the Bezos Earth Fund into perspective. From 2000 to 2016, he found, electric utilities, fossil fuel companies, and the transportation sector collectively spent over $1.2 billion on climate change lobbying. Another study he coauthored found that from 1986 to 2015, five of the largest fossil fuel firms together spent at least $3.6 billion on corporate promotion advertisements in the US. The figures give an incomplete picture of how much Big Oil and Gas has spent in Washington, but they also suggest that Bezos could conceivably keep up all by himself for decades.

The WIRED Guide to Climate Change The world is getting warmer, the weather is getting worse. Here's everything you need to know about what humans can do to stop wrecking the planet.

Of course, it’s not just the amount that matters, but how Bezos—or those he delegates—chooses to spend it. As CEO of Amazon, Bezos hasn’t exactly led the charge on progressive corporate policies around climate change and the environment. The company has been criticized for years by environmental groups like Greenpeace over its business practices and lack of transparency; the nonprofit CDP told Bloomberg News last year that it was one of the biggest carbon emitters in the world outside the fossil fuel industry. Thousands of Bezos’ own workers affiliated with the group Amazon Employees For Climate Justice have pushed for the company to do more to mitigate its enormous impact on the environment, including by staging a walkout.

In that context, it’s easy to see Bezos’ commitment as a shrewd political move meant to pacify his workforce, or atonement for the environmental sins that made him the richest man in the world—a rank he would still hold even minus the $10 billion. Bezos had previously given relatively little of his fortune to charity, choosing instead to spend on efforts like Blue Origin, his space travel company. With one pledge, the CEO immediately joins the philanthropic ranks of tech titans like Bill Gates, who has donated over $45 billion through the Bill and Melinda Gates Foundation.