White House is pushing ahead research to cool Earth by reflecting back sunlight
Full frame sun, Climate change, Heatwave hot sun, Global warming from the sun and burning
Chuchart Duangdaw | Moment | Getty Images
The White House is coordinating a five-year research plan to study ways of modifying the amount of sunlight that reaches the earth to temper the effects of global warming, a process sometimes called solar geoengineering or sunlight reflection.
The research plan will assess climate interventions, including spraying aerosols into the stratosphere to reflect sunlight back into space, and should include goals for research, what’s necessary to analyze the atmosphere, and what impact these kinds of climate interventions may have on Earth, according to the White House‘s Office of Science and Technology Policy. Congress directed the research plan be produced in its spending plan for 2022, which President Joe Biden signed in March.
Some of the techniques, such as spraying sulfur dioxide into the atmosphere, are known to have harmful effects on the environment and human health. But scientists and climate leaders who are concerned that humanity will overshoot its emissions targets say research is important to figure out how best to balance these risks against a possibly catastrophic rise in the Earth’s temperature.
Getting ready to research a topic is a very preliminary step, but it’s notable the White House is formally engaging with what has largely been seen as the stuff of dystopian fantasy. In Kim Stanley Robinson’s science fiction novel, “The Ministry for the Future,” a heat wave in India kills 20 million people and out of desperation, India decides to implement its own strategy of limiting the sunlight that gets to Earth.
Chris Sacca, the founder of climate tech investment fund Lowercarbon Capital, said it’s prudent for the White House to be spearheading the research effort.
“Sunlight reflection has the potential to safeguard the livelihoods of billions of people, and it’s a sign of the White House’s leadership that they’re advancing the research so that any future decisions can be rooted in science not geopolitical brinkmanship,” Sacca told CNBC. (Sacca has donated money to support research in the area, but said he has “zero financial interests beyond philanthropy” in the idea and does not think there should be private business models in the space, he told CNBC.)
Harvard professor David Keith, who first worked on the topic in 1989, said it’s being taken much more seriously now. He points to formal statements of support for researching sunlight reflection from the Environmental Defense Fund, the Union of Concerned Scientists, and the Natural Resources Defense Council, and the creation of a new group he advises called the Climate Overshoot Commission, an international group of scientists and lawmakers that’s evaluating climate interventions in preparation for a world that warms beyond what the Paris Climate Accord recommended.
To be clear, nobody is saying sunlight-reflection modification is the solution to climate change. Reducing emissions remains the priority.
“You cannot judge what the country does on solar-radiation modification without looking at what it is doing in emission reductions, because the priority is emission reductions,” said Janos Pasztor, executive director of the Carnegie Climate Governance Initiative. “Solar-radiation modification will never be a solution to the climate crisis.”
Three ways to reduce sunlight
The idea of sunlight reflection first appeared prominently in a 1965 report to President Lyndon B. Johnson, entitled “Restoring the Quality of Our Environment,” Keith told CNBC. The report floated the idea of spreading particles over the ocean at a cost of $100 per square mile. A one percent change in the reflectivity of the Earth would cost $500 million per year, which does “not seem excessive,” the report said, “considering the extraordinary economic and human importance of climate.”
The estimated price tag has gone up since then. The current estimate is that it would cost $10 billion per year to run a program that cools the Earth by 1 degree Celsius, said Edward A. Parson, a professor of environmental law at UCLA’s law school. But that figure is seen to be remarkably cheap compared to other climate change mitigation initiatives.
A landmark report released in March 2021 from the National Academies of Sciences, Engineering, and Medicine addressed three kinds of solar geoengineering: stratospheric aerosol injection, marine cloud brightening, and cirrus cloud thinning.
Stratospheric aerosol injection would involve flying aircraft into the stratosphere, or between 10 miles and 30 miles skyward, and spraying a fine mist that would hang in the air, reflecting some of the sun’s radiation back into space.
“The stratosphere is calm, and things stay up there for a long time,” Parson told CNBC. “The atmospheric life of stuff that’s injected in the stratosphere is between six months and two years.”
Stratospheric aerosol injection “would immediately take the high end off hot extremes,” Parson said. And also it would “pretty much immediately” slow extreme precipitation events, he said.
“The top-line slogan about stratospheric aerosol injection, which I wrote in a paper more than 10 years ago — but it’s still apt — is fast, cheap and imperfect. Fast is crucial. Nothing else that we do for climate change is fast. Cheap, it’s so cheap,” Parson told CNBC.
“And it’s not imperfect because we haven’t got it right yet. It’s imperfect because the imperfection is embedded in the way it works. The same reason it’s fast is the reason that it’s imperfect, and there’s no way to get around that.”
One option for an aerosol is sulfur dioxide, the cooling effects of which are well known from volcanic eruptions. The 1991 eruption of Mount Pinatubo, for instance, spewed thousands of tons of sulfur dioxide into the stratosphere, causing global temperatures to drop temporarily by about 1 degree Fahrenheit, according to the U.S. Geological Survey.
A giant volcanic mushroom cloud explodes some 20 kilometers high from Mount Pinatubo above almost deserted US Clark Air Base, on June 12, 1991 followed by another more powerful explosion. The eruption of Mount Pinatubo on June 15, 1991 was the second largest volcanic eruption of the twentieth century.
Arlan Naeg | Afp | Getty Images
There’s also a precedent in factories that burn fossil fuels, especially coal. Coal has some sulfur that oxidizes when burned, creating sulfur dioxide. That sulfur dioxide goes through other chemical reactions and eventually falls to the earth as sulfuric acid in rain. But during the time that the sulfur pollution sits in the air, it does serve as a kind of insulation from the heat of the sun.
Ironically, as the world reduces coal burning to curb the carbon dioxide emissions that cause global warming, we’ll also be eliminating the sulfur dioxide emissions that mask some of that warming.
“Sulfur pollution that’s coming out of smokestacks right now is masking between a third and a half of the heating signal from the greenhouse gases humans have already emitted into the atmosphere,” Parson said.
In other words, we’ve been doing one form of sunlight reflection for decades already, but in an uncontrolled fashion, explained Kelly Wanser, the executive director of SilverLining, an organization promoting research and governance of climate interventions.
“This isn’t something totally new and Frankenstein — we’re already doing it; we’re doing it in the most dirty, unplanned way you could possibly do it, and we don’t understand what we’re doing,” Wanser told CNBC.
Spraying sulfur in the stratosphere is not the only way of manipulating the amount of sunlight that gets to the Earth, and some say it’s not the best option.
“Sulfur dioxide is likely not the best aerosol and is by no means the only technique for this. Cloud brightening is a very promising technique as well, for example,” Sacca told CNBC.
Marine cloud brightening involves increasing the reflectivity of clouds that are relatively close to the surface of the ocean with techniques like spraying sea salt crystals into the air. Marine cloud brightening generally gets less attention than stratospheric aerosol injection because it affects a half dozen to a few dozen miles and would potentially only last hours to days, Parson told CNBC.
Cirrus cloud thinning, the third category addressed in the 2021 report from the National Academies, involves thinning mid-level clouds, between 3.7 and 8.1 miles high, to allow heat to escape from the Earth’s surface. It is not technically part of the “solar geoengineering” umbrella category because it does not involve reflecting sunlight, but instead involves increasing the release of thermal radiation.
Known risks to people and the environment
There are significant and well-known risks to some of these techniques — sulfur dioxide aerosol injection, in particular.
First, spraying sulfur into the atmosphere will “mess with the ozone chemistry in a way that might delay the recovery of the ozone layer,” Parson told CNBC.
The Montreal Protocol adopted in 1987 regulates and phases out the use of ozone depleting substances, such as hydrochlorofluorocarbons (HCFCs) which were commonly used in refrigeration and air conditioners, but that healing process is still going on.
Also, sulfates injected into the atmosphere eventually come down as acid rain, which affects soil, water reservoirs, and local ecosystems.
Third, the sulfur in the atmosphere forms very fine particulates that can cause respiratory illness.
The question, then, is whether these known effects are more or less harmful than the warming they would offset.
“Yes, damaging the ozone is bad, acid deposition is bad, respiratory illness is bad, absolutely. And spraying sulfur in the stratosphere would contribute in the bad direction to all of those effects,” Parson told CNBC. “But you also have to ask, how much and relative to what?”
The sulfur already being emitted from the burning of fossil fuels is causing environmental damage and is already killing between 10 million to 20 million people a year due to respiratory illness, said Parson. “So that’s the way we live already,” he said.
Meanwhile, “the world is getting hotter, and there will be catastrophic impacts for many people in the world,” said Pasztor.
“There’s already too much carbon out there. And even if you stop all emissions today, the global temperature will still be high and will remain high for hundreds of years. So, that’s why scientists are saying maybe we need something else, in addition — not instead of — but maybe in addition to everything else that is being done,” he said. “The current action/nonaction of countries collectively — we are committing millions of people to death. That’s what we’re doing.”
For sunlight-reflection technology to become a tool in the climate change mitigation toolbox, awareness among the public and lawmakers has to grow slowly and steadily, according to Tyler Felgenhauer, a researcher at Duke University who studies public policy and risk.
“If it is to rise on to the agenda, it’ll be kind of an evolutionary development where more and more environmental groups are willing to state publicly that they’re for research,” Felgenhauer told CNBC. “We’re arguing it’s not going to be some sort of one big, bad climate event that makes us all suddenly adopt or be open to solar geoengineering — there will be more of a gradual process.”
A man waits for customers displaying fans at his store amid rising temperatures in New Delhi on May 27, 2020. – India is wilting under a heatwave, with the temperature in places reaching 50 degrees Celsius (122 degrees Fahrenheit) and the capital enduring its hottest May day in nearly two decades.
Jewel Samad | Afp | Getty Images
Research it now or be caught off guard later?
Some environmentalists consider sunlight relfection a “moral hazard,” because it offers a relatively easy and inexpensive alternative to doing the work of reducing emissions.
One experiment to study stratospheric aerosols by the Keutsch Group at Harvard was called off in 2021 due to opposition. The experiment would “threaten the reputation and credibility of the climate leadership Sweden wants and must pursue as the only way to deal effectively with the climate crisis: powerful measures for a rapid and just transition to zero emission societies, 100% renewable energy and shutdown of the fossil fuel industry,” an open letter from opponents said.
But proponents insist that researching sunlight-modification technologies should not preclude emissions-reduction work.
“Even the people like me who think it’s very important to do research on these things and to develop the capabilities all agree that the urgent top priority for managing climate change is cutting emissions,” Parson told CNBC.
Keith of Harvard agreed, saying that “we learn more and develop better mechanism[s] for governance.”
Doing research is also important because many onlookers expect that some country, facing an unprecedented climate disaster, will act unilaterally to will try some version of sunlight modification anyway — even if it hasn’t been carefully studied.
“In my opinion, it’s more than 90 percent likely that within the next 20 years, some major nation wants to do this,” Parson said.
Sacca put the odds even higher.
“The odds are 100 percent that some country pursues sunlight reflection, particularly in the wake of seeing millions of their citizens die from extreme weather,” Sacca told CNBC. “The world will not stand idly by and leaders will feel compelled to take action. Our only hope is that by doing the research now, and in public, the world can collaboratively understand the upsides and best methods for any future project.”
Correction: The Climate Overshoot Commission has not issued a formal statement of support for sunlight reflection.
A Tesla vehicle passes the Wilkie D. Ferguson Jr. U.S. Courthouse as jury selection began in connection with allegations regarding the safety of Tesla’s autopilot system on July 14, 2025 in Miami, Florida.
Joe Raedle | Getty Images
Tesla is facing a crucial verdict in a personal injury trial over a fatal Autopilot crash in 2019, the first time Elon Musk’s automaker has been in front of a jury on such a matter in federal court.
Attorneys for the plaintiffs on Thursday asked the jury to award damages of around $345 million. That includes $109 million in compensatory damages and $236 million in punitive damages. The trial in the Southern District of Florida started on July 14.
The suit centers around who shoulders the blame for a deadly crash that occurred in 2019 in Key Largo, Florida. A Tesla owner named George McGee was driving his Model S electric sedan while using the company’s Enhanced Autopilot, a partially automated driving system.
While driving, McGee dropped his mobile phone that he was using and scrambled to pick it up. He said during the trial that he believed Enhanced Autopilot would brake if an obstacle was in the way. He accelerated through an intersection at just over 60 miles per hour, hitting a nearby empty parked car and its owners, who were standing on the other side of their vehicle.
Naibel Benavides, who was 22, died on the scene from injuries sustained in the crash. Her body was discovered about 75 feet away from the point of impact. Her boyfriend, Dillon Angulo, survived but suffered multiple broken bones, a traumatic brain injury and psychological effects.
The plaintiffs have included Benavides’ surviving family members, and Angulo, who testified in the trial. Angulo is seeking compensation for his medical expenses and pain and suffering, while Benavides’ estate is suing for wrongful death, pain and suffering, and other punitive damages.
Lawyers representing the plaintiffs argued that Tesla’s partially automated driving systems, marketed as Autopilot at the time, had dangerous defects, which should have been known and fixed by the company, and that use of Autopilot should have been limited to roads where it could perform safely.
They also argued that Musk and Tesla made false statements to customers, shareholders and the public, overstating the safety benefits and capabilities of Autopilot, which encouraged drivers to overly rely on it.
In opening arguments and throughout the trial, the plaintiffs’ attorneys and expert witnesses cited a litany of Musk’s past promises about Autopilot and Tesla’s autonomous vehicle technology. The lawyers said
Tesla attorneys countered in court that the company had communicated directly with customers about how to use Autopilot and other features, and that McGee’s driving was to blame for the collision. They said in closing arguments that Tesla works to develop technology to save drivers’ lives, and that a ruling against the EV maker would send the wrong message.
The Benavides family had previously sued McGee and settled with him. McGee was charged in October 2019 with careless driving and didn’t contest the charges.
While Tesla has typically been able to settle cases or move Autopilot-related suits into arbitration and out of the public eye, Judge Beth Bloom in the Miami court wrote, in an order in early July, that the case could move ahead to trial.
“A reasonable jury could find that Tesla acted in reckless disregard of human life for the sake of developing their product and maximizing profit,” she wrote in that order.
For closing arguments on Thursday, the Benavides family and Angulo were in the courtroom. They looked away from screens anytime a video or picture of the scene of the crash was displayed.
— NBC News’ Maria Piñero reported from Miami.
Tim Cook arrives for the annual Allen and Co. Sun Valley Media and Technology Conference at the Sun Valley Resort in Sun Valley, Idaho, on July 8, 2025.
David Grogan | CNBC
Apple’s AI strategy and investment was on the mind of analysts on an earnings call after the company reported third-quarter earnings that showed overall revenue grew by 10% year over year.
While Apple was never going to announce major acquisitions or initiatives on an earnings call, CEO Tim Cook’s remarks on Thursday confirm that the company is going to invest more heavily in the technology.
Cook said Apple is going to “significantly” grow the company’s investments in AI. He added that Apple was always looking to buy companies of any size that could help it develop its AI offerings.
“We’re very open to M&A that accelerates our roadmap,” Cook said. “We are are not stuck on a certain size company, although the ones that we have acquired thus far this year are small in nature.”
Cook said that Apple had acquired “around” seven companies so far this year, although not all of them were focused on AI. While Cook has said in the past that Apple is always evaluating potential acquisitions of all sizes, its largest purchase of all time was Beats Electronics in 2014 for $3 billion.
He made the remarks Thursday as Apple has faced growing pressure from Wall Street to catch up to its Silicon Valley peers, all of whom have dedicated tens of billions of dollars toward the infrastructure necessary to power AI.
Apple has never been the biggest spender on capital expenditures among big tech companies. It only reported $3.46 billion in capital expenditures in the June quarter, up from $2.15 billion in the year ago period. Its expenses this past quarter are the highest they have been since the quarter ending December 2022. If Apple spent as much as it did this quarter for a full year, that would be about $14 billion annually.
That hardly compares to Google projecting $85 billion in capital expenditures for its fiscal 2025 last week, Meta’s estimate of as much as $72 billion in annual capital expenditure spending, and Microsoft’s $30 billion capital expenditures guide for the current quarter.
Spending more
“We are significantly growing our investment. We did during the June quarter. We will again in the September quarter,” Cook said.
He added that Apple was rearranging staff internally to focus more on AI.
“We are also reallocating a fair number of people to focus on on AI features within the company,” Cook said. “We have a great team, and we’re putting all of our energy behind it.”
To be clear, Google and Microsoft run cloud businesses that rent out AI hardware, which Apple doesn’t. And Apple finance chief Kevan Parekh said the company has a “hybrid” model to capital investments, in which it gains access to systems it needs through partners and records them as operating expenses.
Apple also said that some of its capex will pay for servers using its own chips, which it calls Private Cloud Compute — not merchant chips from companies such as Nvidia.
“I would say a significant portion of the driver of growth that you’re seeing now is really driven by some of our AI related investments,” Parekh said.
Cook also downplayed any potential that AI-powered devices that haven’t been invented yet might threaten Apple’s iPhone franchise. Apple’s former design guru Jony Ive teamed up with OpenAI in a $6.5 billion May deal, although they have yet to reveal what their product is, does or will cost.
“It’s difficult to see a world where iPhone’s not living in it,” Cook said, “That doesn’t mean that we are not thinking about other things as well, but I think that that the devices are likely to be complementary devices, not substitution.”
Cook also made it clear to investors and analysts on the call that Apple does have an AI strategy that it’s executing on.
“Our focus, from an AI point of view, is on putting AI features across the platform that are deeply personal, private and seamlessly integrated,” Cook said.
When asked if he thought that if large language models — the core AI technology made by companies such as Anthropic and OpenAI — might be commoditized, Cook declined to answer and said he was keeping some parts of the company’s strategy secret for now.
“The way that we look at AI is that it’s one of the most profound technologies of our lifetime” Cook said. “It will affect all devices in a significant way.”
WATCH: Apple CEO Tim Cook: Incurred $800 million in tariff-related costs in June quarter
Figma Inc. signage during the company’s initial public offering (IPO) at the New York Stock Exchange (NYSE) in New York, US, on Thursday, July 31, 2025.
Michael Nagle | Bloomberg | Getty Images
You can almost smell the bubbly wafting across Silicon Valley.
Following Figma’s blockbuster market debut on Thursday, four of the most iconic names in venture capital — Index Ventures, Greylock, Kleiner Perkins and Sequoia — are collectively sitting on roughly $24 billion worth of the design software vendor’s stock.
Until recently, there’s been little reason to celebrate. From late 2021, when soaring inflation and rising rates pushed investors out of risky assets, until the middle of 2025, tech IPOs were few and far between, and many of the companies that managed to make it out failed to impress Wall Street. That’s left venture firms with scarce returns for the pension funds, endowments and foundations they rely on for funding.
The mood is noticeably brighter these days as the Nasdaq trades near a record.
Figma is the latest, and perhaps most high-profile, tech company to hit the market, and Wall Street appears to want more. After raising its price range this week and then pricing $1 above the top of that range, Figma shares soared 250% in their first day on the New York Stock Exchange.
Investors will admit they got lucky. Figma was supposed to get acquired for $20 billion by Adobe, an agreement the two companies forged in 2022. But the following year, the transaction collapsed after U.K. regulators said the tie-up would harm competition.
Figma is now worth more than three times what Adobe was going to pay, closing on Thursday with a market cap of almost $68 billion.
CEO Dylan Field, who co-founded the company in 2012, owns a stake worth over $6 billion. Danny Rimer, a partner at Index Ventures and Figma board member, wrote in a blog post on Thursday that the failed acquisition came with “intense pressure and a spotlight few founders ever face.”
“Dylan remained his usual grounded, transparent self,” wrote Rimer, whose firm first bet on Figma in 2013 and is the biggest shareholder, with $7.2 billion worth of stock in the company. “When the deal fell through a year later, he didn’t flinch. He turned the page and got right back to building.”
Figma’s offering raised $1.2 billion, with two-thirds of the proceeds going to existing investors. Other than the small slug of stock each of the venture firms sold at $33, the rest of their holdings are subject to a lock-up period, meaning all of the current value is currently just on paper. The vast majority of outstanding shares are locked up for 180 days, so big stock sales can’t happen until January.
Stablecoin issuer Circle went public in June, and is the other tech IPO that’s generated hefty returns for VCs recently. The shares were initially sold at $31 each and are now trading at over $183, leaving investment firms IDG Capital, General Catalyst, Accel and Breyer Capital with a combined stake of close to $12 billion. Circle doubled on its first day of trading.
While IPO pops generate a lot of buzz and dramatically lift the value of investors’ holdings, they’re not universally celebrated. Bill Gurley of Benchmark has for years been a critic of such first-day gains, arguing that bankers leave money on the table for the company while handing deeply discounted stock to new investors.
In a series of posts on X on Thursday, Gurley described the Figma outcome as “expected & fully intentional.”
“Who benefits?” Gurley wrote, shortly after the stock began trading. “The large clients of the investment banks (who return the favor paying for other services). They bought it at $33 last night and can sell it today for over $90.”
Return of the exits
Still, the exuberance in the market is welcome news for most VCs.
After a record year in 2021, which saw 155 U.S. venture-backed IPOs raise $60.4 billion, every year since has been relatively dismal, according to data from University of Florida finance professor Jay Ritter. There were 13 such offerings in 2022, followed by 18 in 2023 and 30 last year, collectively raising $13.3 billion, Ritter’s data shows.
The slowdown followed the Federal Reserve’s aggressive rate-hiking campaign in 2022, meant to slow crippling inflation. As the lower-growth environment extended into years two and three, venture firms faced increasing pressure to return cash to investors.
Earlier this year, the exit environment was still looking ominous. After President Donald Trump’s announcement of sweeping tariffs in April, companies including online lender Klarna and ticket marketplace StubHub delayed their IPO plans. The Nasdaq plummeted 10% in a week, as investors fretted over the potential of rising import costs and supply chain disruptions.
But Trump later walked back his threats and the trade deals he’s landed have resulted in lower tariffs than previously feared.
Brannin McBee, Chief Development Officer and Co-founder of CoreWeave, Mike Intrator, Chief Executive Officer and founder of CoreWeave, Peter Salanki, Chief Technology Officer of CoreWeave, and Brian Venturo, Chief Strategy Officer and founder of CoreWeave, pose for photos during the company’s Initial Public Offering(IPO) at the Nasdaq headquarters on March 28, 2025 in New York City.
Michael M. Santiago | Getty Images News | Getty Images
CoreWeave, a provider of artificial intelligence infrastructure, went public just before Trump’s initial plans were announced. The stock is now almost triple its IPO price, closing on Thursday at $114.13, though that’s down about 38% from its high in June.
CoreWeave and Circle have both been big wins for investors, with their market caps now at about $56 billion and $41 billion, respectively. Figma is worth even more.
Lynn Martin, president of the NYSE, told CNBC’s “Squawk on the Street” on Thursday that she thinks the Figma offering “will open the floodgates.”
Figma’s early investors and big financial winners all published glowing blog posts about Field and the journey he’s been on with the company that he started after dropping out of college in 2012.
“Figma’s relentless focus on product, community, and craft has reshaped how the world designs,” wrote Greylock’s John Lilly in a post on Thursday. His firm led the $14 Series AI investment in 2015 and now owns a stake worth about $6.7 billion.
Kleiner Perkins led the $25 Series B, which was announced in 2018. Its holdings are now valued at $6 billion.
“The product was still early, but the love from its small community of users was unmistakable,” wrote Kleiner partner Mamoon Hamid, in his post after the IPO. “We were convinced that Figma had the potential to fundamentally reshape how digital products would be designed, and knew we had to be part of it.”
Two years later, venture powerhouse Sequoia stepped in to lead Figma’s $40 million Series C round. Sequoia’s Andrew Reed wrote at the time that the company had “the talent and culture to build an enduring, fundamental company.”
On Thursday, with his firm’s stake in Figma approaching $3.8 billion, Reed took to X for his congratulatory remarks.
“Congrats to the incredible @Figma team,” Reed wrote. “The most creative, determined, imaginative, and positive group of people. I’m just so happy for all of your success.”
— CNBC’s Jordan Novet contributed to this report.
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