A figure often cited as the necessary domestic investment in decarbonization is about $1 trillion per year, or around 4 to 5% of U.S. GDP. If you’ve been paying attention to D.C. lately, you’re aware that the federal government has nowhere near the political will to muster such a sum, at least not yet.

Congressional Republicans still almost entirely refuse to support government-led climate action, and two Democratic Senators—one of whom earns a half-million a year from coal—will support only watered-down measures. So it’s looking like we’re going to need all the outside funding we can get.

And you know where there is a whole lot of money? Particularly after a proposed billionaires tax went nowhere? In the bank accounts, offshore tax havens and cryptocurrency vaults of the nation’s richest residents. And while climate change has been a niche interest within philanthropy for many years—still largely is—we’ve been seeing more and more ultra-wealthy donors become involved in the issue in recent years—so much so that it’s getting a little hard to keep track.

So I took a look at the nation’s wealthiest donors engaged in the climate fight, starting with those who are most active on the topic, either through a long history of giving or a well-established grantmaking program on the issue. I reviewed what they have funded so far—and their potential to ramp up their giving in the years ahead—and arranged them in ascending order of their estimated assets (not their climate giving, take note).

Also note that there’s a comparable number of other billionaires who aren’t on this list, but are clearly on the cusp of qualifying. In truth, in some cases, it was a hard call. MacKenzie Scott, for example, made a hefty round of giving to the cause, but is just getting started. So stay tuned for a future post on the next wave of ultra-wealthy climate donors, who are either still getting the ball rolling or have given significant, but one-time gifts to this emergency. We’ll also update these lists periodically as we learn more.

As with all of our lists of powerful philanthropists, this is far from a slate of endorsements. These donors are not the saviors many of us want, and the wisdom of their chosen funding strategies is another matter entirely. Nor do we mean to suggest they are a substitute for the full weight, policy power and financial might of the federal government, which (in theory at least) also makes its decisions with some level of democratic process and accountability.

But billionaire donors already play a substantial role in how climate action is unfolding. As history shows in philanthropy’s influence on past social transformations like the Civil Rights Movement, the people and ideas that benefit from their fortunes often determine the paths we proceed down. And with roughly $450 billion in combined wealth, the donors listed here are not exactly dealing with small change. In any case, they are important figures to watch in this critical moment.

Tom Steyer and Kat Taylor: TomKat Foundation, NextGen America, TomKat Ranch

This couple’s high visibility on climate—particularly Steyer, the former hedge fund manager, occasional political candidate and major Democratic donor—shows the ubiquity and influence possible for those who just barely qualify for the 10-figure club. The pair, worth an estimated $1.4 billion, are perhaps best known for their political donations and 501(c)(4) giving. But like others on this list, they back a wide variety of efforts on climate. They make grants through their low-profile TomKat Foundation, which is primarily focused on climate change and clean energy. Steyer’s NextGen America (formerly NextGen Climate) works to mobilize young people through c4 funding, while TomKat Ranch is a sustainable agricultural operation.

Liz Simons and Mark Heising: Heising-Simons Foundation

Climate is one of five priorities for this couple’s $600 million philanthropy, which we’ve been following closely over the years. Its climate and clean energy program focuses on policy, energy sector change and potent pollutants. The couple has around $3 billion in assets, according to Candid. Simons is a former elementary school teacher who, along with Nathaniel Simons (see below) and Audrey Cappell, are children of hedge fund co-founder Jim Simons, whose wealth is estimated at $24 billion. Mark Heising, himself an investor and a former computer chip engineer with six U.S. patents, now runs a family office that, in 2018, was managing more than $3 billion in assets for Simons family foundations and charities.

Learn more: A Growing Climate Funder Works to Change the “Rules of the Road” Through Energy Policy

Nat Simons and Laura Baxter-Simons: Sea Change Foundation*

This couple runs one of the country’s largest funders of climate and clean energy work. In fact, for years, they were the biggest living donors in the game, albeit flying almost entirely under the radar until just a few years ago. Sea Change is solely focused on climate, with initiatives on cooling, clean transportation, and corporate partnerships. Part of the couple’s philanthropy comes from a multibillion-dollar, Bermuda-based trust established by Jim Simons long ago, a portion of which fuels what’s now known as Sea Change Foundation International. Aside from Simons family wealth, Nat is head of Meritage Group, which manages more than $11 billion in funds, while Laura serves as its general counsel and chief compliance officer. The couple also co-founded Prelude Ventures, a venture capital investment fund that channels Simons family wealth toward climate solutions.

* This one gets an asterisk because, while no public sources tag them as billionaires, it seems like a fair assumption based on what we know.

Learn more: Top Climate Change Donors Pull Back the Curtain on Their Past and Future Giving

John and Ann Doerr: Benificus Foundation

The Kleiner Perkins chairman and his wife, Ann, run the low-profile Benificus Foundation, which is one of the top 40 climate funders by some counts and had $395 million in assets as of 2019. The environment is one of two focus areas. One major grantee is the Al Gore-founded Climate Reality Project and the Environmental Defense Fund has been a recipient, too. Unsurprisingly, this venture capitalist is said to take a venture capitalist approach to philanthropy. So perhaps it’s worth mentioning he’s among those who’ve put money into Bill Gates’ Breakthrough Energy group, as well as climate funds that recently got buy-in from other major philanthropists. Doerr is a Giving Pledge signatory, so it’s likely that the 70-year-old, who’s believed to have about $14 billion in assets, will put more into philanthropy in the years ahead.

Eric and Wendy Schmidt: Schmidt Family Foundation, 11th Hour Project, etc.

Like others on this list, the former Google CEO and Alphabet board member’s giving on climate change can be a little tricky to understand. The 66-year-old and his wife, Wendy, run the Schmidt Family Foundation, which counts the environment among its priorities. Its giving on the issue, however, largely runs through the 11th Hour Project, which is housed within the foundation, and has become one of the largest funders in the space. Another branch of their philanthropy, Schmidt Futures, has also made sizable grants in this area. Still another arm, Schmidt Ocean Institute, also touches on climate. The Schmidts, who are worth an estimated $24 billion, have really ramped up their philanthropy in recent years. Is more to come in this decisive decade?

Learn more: Fight Locally: Inside the 11th Hour Project, a Top Climate Funder

Mike Bloomberg: Bloomberg Philanthropies

The former New York City mayor and financial media conglomerate co-founder has put a major share of his philanthropy toward battling climate change, including $500 million in 2019 to launch his retooled Beyond Carbon campaign. Bloomberg Philanthropies had previously spent years and millions funding the phasing out of coal plants. Oceans and cities have been other major focal points. Known for his data-driven approach to giving, the 79-year-old has made some questionable moves on climate, such as his enthusiastic support of natural gas in the past. But he’s been a massive presence in the field—and with an estimated $70 billion in assets, he will likely do a lot more.

Learn more: Game Changer? The Promise and Perils of Bloomberg’s Big New Climate Funding Push

Bill Gates and Melinda French Gates: Bill and Melinda Gates Foundation, Breakthrough Energy

While this divorcing couple co-lead the world’s largest foundation, climate seems to be a major interest for the Microsoft co-founder, one which he’s funding through an array of vehicles. Yes, some support flows through the $50 billion-plus Bill and Melinda Gates Foundation, whose climate grants include support for African farmers, among other issues. But there are other channels. His Breakthrough Energy group is known for marshaling investors—including many on this list—but it also takes philanthropic actions, like signing onto a recent methane emissions reduction alliance. And he’s personally funded geoengineering research, which some see as an emergency option to forestall warming. Agree with his tech-centric approach to climate change or not, Gates has shown admirable willingness to put his roughly $138 billion fortune to work. It seems likely we’ll see greater spending on climate from him in the years ahead. Heck, he even published a book on the topic.

Learn more: The Gates Foundation Gives Big for Climate Change. Does It Have the Right Priorities?

Jeff Bezos: Bezos Earth Fund 

With an Instagram post early last year, the Amazon founder went from a non-entity in climate philanthropy to the single biggest funder of the issue (though the competition for that title is not quite as stiff as one would hope). His $10 billion Bezos Earth Fund, which plans to spend down over 10 years, joined a foundation community that collectively spent only $1.6 billion in 2019. More than most on this list, the 57-year-old has put a sizable share of funding toward environmental justice, including unprecedented grants to pooled funds and recent awards to some of the field’s legends. Bezos is relatively new to the field, but has made multiple rounds of huge gifts, and his philanthropic operation continues to add staff. The question now is whether it will actually take a full decade to spend his pledge—or if it is only the beginning of his climate philanthropy. With an estimated $200 billion in wealth, he’s got lots of options.

Learn more: The Bezos Earth Fund’s Latest Grants Favor Environmental Justice Veterans and Federal Action

Did I miss your favorite American mega-billionaire who’s put beaucoup bucks into climate philanthropy? Let me know at [email protected]