In his three-decade career, he has produced groundbreaking research on global warming and the ocean acidification that has killed off coral reefs. But Caldeira’s most profound influence in science may be as an adviser, be it to students or to one of the world’s richest men, as billionaires fund climate research.A yellow skiff darted across a lagoon along Australia’s northeast coast, throttling down as it approached a shallow coral reef. Climate scientist Ken Caldeira piloted the craft while a younger colleague, oceanographer Manoela Romanó de Orte, sat on the bow holding a syringe filled with red dye. Romanó de Orte injected the dye into the water, then recorded the coordinates of the spot as Caldeira maneuvered away from the expanding scarlet cloud. That bloom would soon help them gauge how well this part of the Great Barrier Reef is recovering from a series of climate-change shocks. Caldeira, 64, may have been at the boat’s helm, but on this day, Romanó de Orte, his 36-year-old postdoctoral employee, was in charge. Essentially, Caldeira was her research assistant, despite being one of the most influential climate scientists of his generation. Caldeira ranks 26th on the Reuters Hot List, which measures the clout of the top 1,000 scientists studying climate change, both among their peers and the public. In his three-decade career, the American has produced groundbreaking research on ocean acidification – the process by which gases emitted by the burning of fossil fuels are changing the chemistry of the sea and, among other impacts, killing coral.He was among the first to calculate the Herculean effort needed to keep the planet’s average temperature from rising 2 degrees Celsius above the pre-industrial level of the mid-1800s. If that point is breached, scientists project, sea levels are likely to rise two to eight feet in the next century. Coral reefs will probably disappear. Some parts of the world may become unlivable. Along the way to pre-eminence, Caldeira has courted controversy as well, by challenging environmentalist orthodoxies. He examined how geoengineering – manipulating the environment – might minimize the effect of the carbon dioxide that humankind is spewing into the atmosphere. (In the end, he concluded it isn’t a prudent solution.) A former anti-nuclear activist, he has aligned with scientists who believe nuclear power – which doesn’t emit greenhouse gases – could help us wean ourselves off fossil fuels. The Hot List series The Pioneer The Rarity The Adviser The Paradox The Cassandra The Target The List But for all that, Caldeira’s most profound influence on science may be as an advisor, whether on the weeklong trip to study the vulnerable coral beds off Lizard Island or as a senior adviser to one of the world’s richest men, Microsoft founder Bill Gates. For most of the last 15 years, Caldeira worked at the Carnegie Institution for Science in Palo Alto, California, founded by Andrew Carnegie, the railroad and steel tycoon who gave away 90% of his fortune before he died. A year ago, he started working for Gates, arguably the most influential philanthropist of our time. Gates, too, has pledged to give away most of his fortune, and plans to plow some of those billions into climate-change research and solutions. Caldeira is helping his new boss decide how to spend that money. At a time when some right-leaning governments are resisting climate research, billionaire donors offer scientists another route – especially for ideas based on cost-efficient solutions, a favorite of entrepreneurs the world over. It’s a controversial trend among some researchers and environmentalists, who see a risk of tycoons tilting the agenda to suit their interests. Gates himself has been under heat recently for taking such a prominent role in the debate, especially given that he’s a major investor in the climate-unfriendly private-jet industry. In his new book, he admits to being an “imperfect messenger.” Gates, however, told Reuters that his money is highly unlikely to have undue influence. “Philanthropy can stimulate the development of some of these early-stage ideas, but relative to long-term government spending, charitable giving will be quite small,” he said in an email interview. Caldeira, a former stick-it-to-the-establishment environmentalist, says he gets the concern. He says he isn’t particularly worried, however, reflecting a pragmatism that has grown in him over the years. Caldeira believes that with Gates’ background in technology, he may well spot clever solutions that might be missed if all climate-change research were funded by governments. “Put it this way,” he said. “If I had a lump of money to invest to achieve some goal, and you told me that either I could invest it myself, or the federal government could invest it for me, or Bill Gates could invest it for me, I would pick Bill Gates without a moment’s hesitation.”Caldeira lives in a modernist home with a wall of glass doors that offer an unobstructed view of San Francisco Bay. He adjusts the temperature using his phone and weighs the liquor for his cocktails on a digital scale. It’s a long way from his youth in suburban New Jersey in the 1970s. It was the early days of home computers, which were rare and mostly mail-order kits, assembled by nerds like Bill Gates. It was around the time that Gates and Paul Allen founded Microsoft, but still a decade before they released the first version of the Windows operating system. Caldeira, meanwhile, was feeding his head with LSD. Then he got access to a computer at school. “Programming basically saved my life because it gave me another world to go into that gave the same kind of fantasy escape from reality,” he said. “I basically shifted from an addiction to hallucinogens to addiction to computer programming.” By the early 1980s, he got a job as a programmer for a large bank’s New York City mergers and acquisitions department. The bankers paid him well to help determine the profitability of their deals, but he grew tired of “helping rich people get a little richer.” In 1985, he took a holiday in Mexico, where he ran into a team of herpetologists studying crocodiles. It changed his life. He was fascinated by the work and offered the researchers a trade: his programming skills in exchange for work as a field assistant. They needed someone to input their observations into a computer and turn them into maps.“They paid me Mexican minimum wage,” he said. “One of the projects was catch-and-release of crocodiles and pumping their stomach and seeing what they were eating. And I said, if I want to lead an expedition like this, I have to get a Ph.D.” Back in New York, he eventually saw an ad in a magazine for the climate science graduate program at New York University. Caldeira went in and talked to department chief Marty Hoffert. Caldeira was unqualified, Hoffert says: He had studied philosophy in college and lacked the requisite math, physics and other courses. But Hoffert says he realized Caldeira “had an extraordinary mind,” so he admitted him on the condition he take undergrad courses to catch up. Caldeira now refers to Hoffert as his “scientific father.” Anti-nuke to pro-nukeish In 1993, Hoffert helped Caldeira get a job at California’s Lawrence Livermore National Laboratory, one of the birthplaces of the U.S. nuclear weapons program. Don"t miss more stories in this series. Sign up for updates on WhatsApp here Join our #AskReuters Twitter chat with Michael Oppenheimer and Corinne Le Quéré. April 22 06:30 PM https://twitter.com/Reuters/ Ask The Hot List scientists anything on Reddit Starts April 29 06:00 PM https://www.reddit.com/r/askscience In his 13 years there, Caldeira had nothing to do with weapons or nuclear energy. He was studying issues such as atmospheric carbon dioxide levels. But Caldeira says it was an ironic place to land: He had been an anti-nukes organizer in the 1980s. His activism had its roots in nuclear meltdowns, one fictional and one real. In March 1979, “The China Syndrome” opened in cinemas. The film told the tale of a nuclear plant meltdown that threatened to burn through the Earth’s crust. Sixteen days later, news broke of an accident at the Three Mile Island nuclear plant in southern Pennsylvania. There was a risk of a catastrophic meltdown. Fearing a radioactive plume might waft their way, Caldeira, his girlfriend and two friends left the New York City area, driving on a route they believed would keep them safe. Engineers at Three Mile Island eventually averted a disaster. But by the time he returned home, Caldeira had committed to the anti-nuke cause. He was eventually arrested several times at protests outside nuclear plants and at anti-nuclear weapons marches. In the coming decades, his thinking has turned more pragmatic, and for that he credits his mentor. In 1998, Hoffert asked Caldeira to collaborate on a study that looked at how much energy would be needed in coming years to sustain the economy while also phasing out fossil fuels. Humanity faced a Catch-22. The world economy was expanding 2% to 3% a year, requiring commensurate rises in power to drive that growth, Hoffert said. “He developed a model where we basically found that we would have to phase out virtually all fossil fuel CO2 emissions, something like 80% within the next 50 years, which nobody has been saying,” he said, recalling the 23-year-old paper. “And that was an incredibly shocking number.” At the time, they concluded that wind and solar power wouldn’t be sufficient, and the solution would likely require some nuclear energy. “It’s very hard to see a pathway out of this without a significant role for nuclear power,” said the pioneering American climatologist James Hansen, who in the 1980s was among the first scientists to raise the alarm about climate change. Too many scientists, Hansen said, shy away from discussing nuclear power, for fear of the inevitable blowback from environmentalists. Caldeira isn’t one of them. In 2013, two years after the Fukushima Daiichi nuclear power plant meltdown in Japan, Hansen persuaded Caldeira and three other prominent climate scientists to join him in signing an open letter. Nuclear power, they declared, is an essential part of solving the climate-change riddle.Caldeira says that Hansen, fifth on the Hot List, is more sanguine about nuclear power than he is. Caldeira points to the safety risks and cost of having thousands of nuclear power plants, which remain enormously expensive to run, around the world. He’d rather find cheaper and more politically palatable ways ahead. For example, he recently co-authored a paper that contemplated using solar and wind to both generate electricity and create hydrogen gas, which doesn’t produce planet-warming carbon dioxide when burned. Those gas stores could then be used to create electricity when the sun’s not shining or the wind’s not blowing. Still, humanity should remain open to nukes, Caldeira says. Applying science Caldeira has entertained other unpopular notions. He recalled a meeting he attended while working at Lawrence Livermore in the late 1990s. Several colleagues were there, including his friend Lowell Wood, a protege of Edward Teller, father of the hydrogen bomb. Wood knew of Caldeira’s interest in climate change and pitched an idea: Suspending reflective particles in the atmosphere – a form of geoengineering – could cool the planet. Caldeira took it seriously. Back at the lab, he recruited a colleague to run the first-ever three-dimensional model simulation of the idea. “It worked much better than I had anticipated,” he recalled. Objections poured in from environmentalists, who thought such solutions would only take the pressure off the oil industry to confront its responsibility for climate change. Some scientists, too, protested that messing with the climate was dangerous.In the end, Caldeira concluded that geoengineering wouldn’t solve the climate-change problem. It would just mask it: Without a significant reduction of emissions, warming gases would still accumulate in the air, resulting in an ever-increasing need to alter the atmosphere. (Although Caldeira soured on the idea, the National Academies of Sciences, Engineering and Medicine recently released a report calling on the U.S. government to investigate blocking sunlight that’s heating the planet as greenhouse gases continue accumulating.) “Even if you think geoengineering works,” he said, “it doesn’t save you from the need of transforming your energy system.” Fundamentally, the key is eliminating fossil fuels. And that is the rub: Caldeira struggles to see how the nearly 200 nations of the planet – with wildly varying stakes in today’s petroleum-centric energy system – can resolve their competing interests. It’s why, when asked about the future, he said, only half-jokingly, “We’re fucked.” Part of the problem, Caldeira believes, is the very institutions and pacts aimed at solving climate change, including the 2016 Paris Agreement. He thinks the world needs these efforts, but says their weakness is that they create long-term goals, not immediate obligations to cut emissions. Instead, governments should commit to two-year goals, demonstrate compliance and then commit to new targets. The power (and peril) of philanthropy Another obstacle, Caldeira says, is the lobbying clout of the fossil fuel industry and businesses, as well as governments, that rely on cheap access to those fuels. In the past. their influence has overwhelmed that of the nascent renewables industries and could snuff out even better technologies in the future. Philanthropists, however, might alter that balance of power, Caldeira and Gates believe. “At this point, we don’t know which ideas will have a real impact,” Gates said in the email interview. “We need thousands of ideas to be funded and pursued in order to have the tools we need to reduce the worst impacts of climate change.” In February 2020, Caldeira joined the Gates universe and is now a senior scientist at Breakthrough Energy, a nonprofit investment fund Gates founded in 2015 with a goal to shift the world’s economy off fossil fuels. The two met about 15 years ago after a Gates employee approached Caldeira about conducting a “learning session” on climate change for the tech billionaire, a famously voracious student of all sorts of science. Caldeira says those sessions, which he led but involved climate scientists and thinkers from around the world, helped him realize that he, too, had more to learn. His relationship with Gates blossomed over those sessions, he said. Eventually, Gates decided to invest in Caldeira’s lab at Stanford and has been subsidizing Caldeira’s lab for 13 years. In 2019, Gates provided about $750,000, three-quarters of Caldeira’s research budget. Gates has plenty of company. In recent years, the multibillionaire class has increasingly bankrolled climate scientists and invested in green technologies. Michael Bloomberg put $500 million behind his own Beyond Carbon project, with the goal of having the U.S. economy go 100% carbon-free. In September, Amazon founder Jeff Bezos announced that the online commerce giant had invested $2 billion in companies developing technologies and products that will reduce the need for fossil fuels. In November, Bezos announced he was earmarking $700 million of a promised $10 billion in contributions from his Earth Fund for climate change and environmental organizations.The Climateworks Foundation, a nonprofit that channels donations to researchers, estimates that total U.S. charitable giving related to climate change amounted to between $5 billion and $9 billion in 2019. About $1.6 billion of that came from large foundations. By contrast, in 2017, the most recent year data is available, the U.S. federal government spent about $13.1 billion on climate change-related science, research and mitigation, the Government Accounting Office estimates. Most climate scientists and activists welcome the infusion of cash; Caldeira compares it to priming the pump. They say the need has grown especially acute in recent years, as governments in some leading nations have spurned the findings of climate science and promoted the fossil fuel industry. Others, however, worry that the billionaires’ outsized wealth lets them set priorities that might not coincide with the best interests of the planet. Gates, Bezos and others aren’t like earlier generations of fabulously wealthy donors, said Stan Katz, a Princeton professor who has studied philanthropy for 45 years. Today’s tycoons are intimately involved in all aspects of their giving, from vaccine research to climate studies. That’s different from Carnegie and John D. Rockefeller, whose foundations were largely run by independent boards of directors.“Bill Gates doesn’t work on the basis of peer-to-peer review, so there"s no community judgment involved,” Katz said. What the philanthropists believe is best will get funded, he says, rather than what scientists conclude is necessary. “I think what that means is that individuals now are in a position to purchase public policy.” Gates addresses the issue in his latest book, “How to Avoid a Climate Disaster,” which Caldeira spent the last few months helping fact-check. “The world is not exactly lacking in rich men with big ideas about what other people should do, or who think technology can fix any problem,” Gates writes in the book’s introduction. “And I own big houses and fly in private planes – in fact, I took one to Paris for the climate conference – so who am I to lecture anyone on the environment? I plead guilty to all three charges. “I can’t deny being a rich guy with an opinion. “I do believe, though, that it is an informed opinion, and I am always trying to learn more.” That’s where Caldeira comes in. Gates describes him as a practical thinker who can help him win victories in the policy arena. “Ken is phenomenal at translating deeply scientific concepts for people without scientific expertise,” Gates said. “He is also very aware of the political and economic implications of this work. Both skills are very important, since the only way we can hope to make progress on climate change is if people understand what"s at stake and can help push the policy and business worlds to take action.” Endangered oceans Humans, says Caldeira, are “the ultimate invasive species.” We will somehow adapt, he thinks, however much the planet warms. Coral and many other creatures and plants won’t fare nearly as well. Lizard Island shows why. The reef around the island is part of the Great Barrier Reef, the world’s largest, stretching about 1,500 miles along Australia’s northeast coast. A recent study found that the Barrier Reef had lost about half its coral since 1995. It suffered another destructive bleaching episode last year, and scientists worry there could be another this year. It’s no surprise to Caldeira. In 2007, he predicted reefs’ demise in one of his most influential papers, which identified ocean acidification as a growing threat. He documented how carbon dioxide from the burning of fossil fuels is being absorbed by oceans, making them more acidic, corrosive to coral’s calcium carbonate skeletons. Coral’s problems are compounded by the warming of sea water, he found.Caldeira can see a time in the coming decades in which almost all reefs will disappear. The last time that happened was the end of the Cretaceous period, when the dinosaurs went extinct following a massive meteor strike. The resulting dust cloud reflected sunlight away from the planet, causing temperatures to plummet. Three-quarters of the planet"s species went extinct. “Basically, coral reefs go out of the geologic record for several hundred thousand years,” he explained. Tiny coral colonies must have found a way to hold on until conditions in the seas improved enough for new reefs to form, he said, recalling the subject of his 1991 Ph.D. thesis. Today, corals face the opposite problem: The oceans are too hot. It takes about a decade for a living reef to recover from a major storm or an underwater heatwave and the subsequent bleaching. Until recently, reefs typically had time to recover. Global warming has changed that. The Great Barrier Reef has suffered through repeated heat shocks and bleachings in recent years. Romanó de Orte’s first trip to Lizard Island came the year after a disastrous heatwave in 2017, shortly after joining Caldeira’s Carnegie team. That year, the two spent up to five hours a day in the water, working on her project to gauge whether changes in carbonate levels in seawater during the day and night were indicative of a growing reef. No, they concluded: The variations were false signs of hope.That journey also served as another test – of whether Caldeira himself could follow his own “scientific father,” Hoffert, as a nurturing mentor. Caldeira loves the limelight. He enjoys dropping the names of the rich and famous who seek his counsel. He dreamed in youth of being a rock star and, until the pandemic, played bass in a pickup band with other scientists. In one of my early conversations with him, he blurted out: “Did you know that I invented the term ‘ocean acidification’?” (He quickly corrected himself. Although a giant in that specialty, he didn’t coin the phrase, but did help popularize it.) At Lizard Island, though, Romanó de Orte ran the project. “He said, ‘You are the boss,’” she recalled. “And so he would say, ‘Should I do this? Should I not do this?’ And I would be the one making decisions.” Caldeira is approaching the age when many peers are retiring. “When I was younger, I was more focused on putting myself out front,” he said, “and now I am getting more satisfaction helping others be successful.”