Once a dystopian fantasy, manipulating sunlight to cool the earth is now on the White House research agenda
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 the 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 humanity will overshoot its emissions targets say research is important to figure out how 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 heatwave 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, says 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 to support research in the area, but 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 first worked on the topic in 1989, and says it’s being taken much more seriously now. He points to a formal statement of support for research from a group he advises called the Overshoot Commission. The Environmental Defense Fund, the Union of Concerned Scientists, and the Natural Resources Defense Council have also indicated support for research into the topic.
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, the 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 says, “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 one degree Celsius, said Edward A. Parson, a professor of environmental law at UCLA’s law school. But that is remarkably cheap compared to other climate change mitigation efforts.
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, which is between 10 and 30 miles up, 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 too, 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 burns, 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 with terrible warming effects, explains 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 surface of the earth. 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 on September 16, 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 ongoing.
Also, sulfates injected into the atmosphere eventually come down as acid rain, which affects soil, water reservoirs, and local ecosystems.
Thirdly, the sulfur in the atmosphere forms very fine particulates that 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 already causing environmental damage and is already killing between 10 and 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/non action 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 onto 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 have “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 agrees. His goal is “simply that we learn more and develop better mechanism[s] for governance,” he told CNBC.
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.”
Tesla displays Optimus next to two of its vehicles at the World Robot Conference in Beijing on Aug. 22, 2024.
CNBC | Evelyn
Tesla’s vice president of Optimus robotics, Milan Kovac, said on Friday that he’s leaving the company.
In a post on X, Kovac thanked Tesla CEO Elon Musk and reminisced about his tenure, which began in 2016.
“I want to thank @elonmusk from the bottom of my heart for his trust and teachings over the decade we’ve worked together,” Kovac wrote. “Elon, you’ve taught me to discern signal from noise, hardcore resilience, and many fundamental principles of engineering. I am forever grateful. Tesla will win, I guarantee you that.”
Tesla is developing Optimus with the aim of someday selling it as a bipedal, intelligent robot capable of everything from factory work to babysitting.
In a first-quarter shareholder deck, Tesla said it was on target for “builds of Optimus on our Fremont pilot production line in 2025, with wider deployment of bots doing useful work across our factories.”
During Tesla’s 2024 annual shareholder meeting, Musk characterized himself as “pathologically optimistic,” then claimed the humanoid robots would lift the company’s market cap to $25 trillion at an unspecified future date.
In recent weeks, Musk told CNBC’s David Faber that Tesla is now training its Optimus systems to do “primitive tasks,” like picking up objects, open a door or throw a ball.
Competitors in the space include Boston Dynamics, Agility Robotics, Apptronik, 1X and Figure.
Kovac had previously served as the company’s director of Autopilot software engineering. He rose to lead the company’s Optimus unit as vice president in 2022.
Musk personally thanked Kovac for his “outstanding contributions” to the business.
Tesla didn’t respond to a request for comment.
President Donald Trump holds a news conference with Elon Musk to mark the end of the Tesla CEO’s tenure as a special government employee overseeing the U.S. DOGE Service on Friday May 30, 2025 in the Oval Office of the White House in Washington.
Tom Brenner | The Washington Post | Getty Images
Tesla has been facing massive challenges trying to get back on track after a disastrous first quarter. Those headwinds strengthened considerably this week.
CEO Elon Musk officially concluded his term with the Trump administration at the end of May, hitting the 130-day mark, the maximum time allowed for a “special government employee.” On his way out the door, Musk expressed sharp criticism of the Trump’s signature spending bill that’s being debated in Congress due to its expected impact on the national debt.
What started off as a policy disagreement quickly escalated into an all-out online brawl, with Musk and President Donald Trump hurling insults at one other from their respective social media platforms. After Musk called the “one, big beautiful bill” an “abomination” and rallied his followers on X to “kill the bill,” Trump said Musk had gone “CRAZY” and threatened to end government contracts and cut off subsidies for Musk’s companies. Musk responded, “Go ahead, make my day.”
The rift sent Tesla shares plummeting 14% on Thursday, wiping out roughly $152 billion in value, the most for any day in the company’s 15 year-history on the public market. While Musk is still the richest person in the world on paper, his net worth plunged by $34 billion, according to Bloomberg’s Billionaires Index.
More importantly, the spat brought about the collapse to a relationship that blended business, politics and power in a manner virtually unprecedented in U.S. history. The ramifications to Tesla, which fell out of the trillion-dollar club on Thursday, could be severe, and not just because Trump is reportedly considering selling or giving away the red Model S he purchased in March after turning the White House lawn into a Tesla showroom.
A senior White House official told NBC News on Friday that the president was “not interested” in having a call with Musk to resolve their feud.
Ire from the Trump administration could influence everything from future regulation, investigations and government support for Tesla, to decisions on tariff exemptions the company has been seeking in order to purchase Chinese-made manufacturing equipment.
Tesla shares were badly underperforming the broader market before the Musk-Trump breakup. Revenue slid 9% in the first quarter from a year earlier, with auto revenue plummeting 20%, due to the combination of increased competition from lower-cost EV makers in China and a consumer backlash to Trump’s political activities and rhetoric.
It’s certainly not what Tesla shareholders were expecting, when they sent the stock up about 30% in the days following Trump’s election victory in November. After spending close to $300 million to return Trump to the White House, Musk was poised to have a major role in the administration and be in position to push through regulatory changes in ways that benefited his companies.
Instead, his company has suffered, and Musk’s behavior is largely to blame.
One of his most divisive actions in leading the Trump administration’s Department of Government Efficiency (DOGE) was the dismantling of USAID, which previously delivered billions of dollars of food and medicine to more than 100 countries.
Beyond the U.S., Musk has endorsed Germany’s far-right extremist party AfD, and gave a gesture that many viewed as a Nazi salute at an inauguration rally.
In response, in recent months, there were numerous cases of vandalism or arson of Tesla facilities or vehicles in the U.S., as well as waves of peaceful protests at Tesla stores and service centers in North America and Europe.
Advertisements in protest of Musk have appeared in New York’s Times Square, and at bus shelters in London, urging people to boycott Tesla, some labeling the company’s EVs as “swasticars.” The Vancouver International Auto Show even removed Tesla from its exhibitors’ list fearing the company’s presence would cause safety problems.
On top all that are President Trump’s sweeping tariffs, which have led to concerns that costs will increase for parts and materials crucial for EV production. In its first-quarter earnings report in April, Tesla refrained from promising growth this year and said it will “revisit our 2025 guidance in our Q2 update.”
Board is mum
Pension funds that invest in Tesla have said the “crisis” at the company requires a leader to work a minimum of 40 hours per week to focus on solving its problems.
Public officials are echoing that sentiment, and calling on Tesla’s board to take action.
New York City Comptroller Brad Lander said on Thursday in s statement to CNBC that the “schoolyard fight” between Trump and Musk highlights how “Tesla’s weak accountability measures and poor governance threaten not only the company’s financial stability and shareholder value, but also the future of homegrown EV production.”
Brooke Lierman, comptroller of Maryland, told CNBC in an email that the company’s board “is not doing its job to ensure that there is a CEO at Tesla who is putting the company’s interests first.”
Since Musk’s name is synonymous with Tesla, the board needs to ensure that Tesla can stand on its own regardless of who’s leading the company, she added.
“Musk’s behavior continues to threaten the future of Tesla,” Lierman said. “As long as Tesla is identified with Elon Musk and he continues to be a polarizing figure, he will continue to damage the brand which is a huge part of Tesla’s value.”
Musk didn’t respond to a request for comment. CNBC also reached out for comment to board chair Robyn Denholm and directors and executives who work in government relations and in the office of the CEO. None of them responded as of the time of publication.
Elon Musk interviews on CNBC from the Tesla Headquarters in Texas.
CNBC
Tesla investors focused on business fundamentals are justified in their skepticism.
The company has failed to roll out innovative and affordable new model EVs, while Chinese competitors like BYD have flooded the market, particularly in Europe.
Analysts at Goldman Sachs on Thursday lowered their price target on Tesla mostly due to the outlook for 2025. Deliveries this quarter are tracking lower for the U.S., the analysts noted, while European sales saw a 50% year-over-year decline in April and another double-digit drop in May. China sales from those two months were down about 20% from a year earlier.
Quality is also a problem. Tesla has announced eight voluntary recalls of the Cybertruck in 15 months due to a range of issues including software bugs and sticking accelerator pedals.
Robotaxi ready?
Musk is urging investors to largely ignore the core business and look to the future, which he says is all about autonomous vehicles and humanoid robots.
But even there, Tesla is behind. In AVs the company has ceded ground to Alphabet’s Waymo, which is operating commercial robotaxi services in several U.S. markets. After a decade of missed deadlines, Musk has promised a small launch of a Tesla driverless ride-hailing service in Austin this month.
The Austin robotaxi service will operate in a geofenced area, Musk said in a recent interview with CNBC’s David Faber, and will begin with a small fleet of just 10 to 20 Model Y vehicles with Full Self-Driving (FSD) Unsupervised technology installed. If all goes well, Musk has said, Tesla will try to rapidly expand its driverless offerings to other markets like San Francisco and Los Angeles.
What consumers won’t be seeing anytime soon are the Cybercab and Robovan vehicles that Tesla touted at its “We, Robot” event last year to drum up customer and investor enthusiasm.
On Friday, Milan Kovac, Tesla’s vice president of Optimus robotics, announced he was leaving after joining the company in 2016. Musk thanked him for his “outstanding contribution” in a post on X.
Still, there are plenty Tesla bulls and Musk fanboys who are believers in the CEO’s vision. The stock’s 4% rebound on Friday is a sign that some saw an opportunity to buy the dip.
“I think the real story here is the investor base of Tesla literally doesn’t care about anything,” Josh Brown, CEO of Ritholtz Wealth Management and CNBC PRO contributor, told CNBC’s “Halftime Report” Friday. “This is still a nothing matters stock.”
FundStrat’s Tom Lee said the Tesla selloff was “overdone.”
Tesla’s market cap, which is dramatically inflated relative to every other U.S. car maker, is built on Musk’s vision of Tesla’s Optimus humanoid robots doing factory work and babysitting our children, while self-driving Cybercabs and Robovans make money carting around passengers.
Morgan Stanley’s Adam Jonas wrote in a note this week that, “Tesla still holds so many valuable cards that are largely apolitical,” pointing to what he sees as the company’s “AI leadership, autonomy/robotics, manufacturing, supply chain re-architecture, renewable power, [and] critical infrastructure.”
In terms of Tesla’s existing business, the most immediate impact from what’s happening in Washington D.C., is the rollback of EV credits in the current budget bill that Musk loudly opposes and that’s struggling to find sufficient support in the Senate. There’s also the matter of the tariffs and whether Tesla is able to get preferred treatment, a proposition that seems increasingly unlikely with the Musk-Trump fallout.
Matthew LaBrot, a former Tesla staff program manager, told CNBC that he’s not surprised that Musk blew up his relationship with the president. LaBrot was terminated earlier this year after sending an open letter in protest of Musk’s divisive political activity.
“I am devastated for the country and the climate, though Elon only has himself to blame,” LaBrot said in an interview. “Back a loose canon, expect stray canon fire.”
Tesla investors can’t know at the moment how much of Musk’s energy and time will now return to his lone public company, and the business responsible for the vast majority of his wealth. Even without politics, he still has SpaceX, AI startup xAI and brain tech startup Neuralink, among other businesses.
As of Thursday, Musk still had a West Wing office that hadn’t been cleaned out, two administration officials told NBC News. The space will likely be packed up in the coming days, one of the officials said.
And while his time in the Trump camp may be over, Musk has called on his followers to form a new party in the U.S.
“Is it time to create a new political party in America that actually represents the 80% in the middle?” he wrote on X on Thursday, in a post that’s now pinned at the top of his page. According to the post, 80% of 5.6 million respondents to the unofficial poll said “yes.”
Musk’s actions this week may have caused a permanent rift with the president. But one thing is clear — his company can’t get away from the White House.
The Docusign Inc. application for download in the Apple App Store on a smartphone arranged in Dobbs Ferry, New York, U.S., on Thursday, April 1, 2021.
Tiffany Hagler-Geard | Bloomberg | Getty Images
Shares of DocuSign tanked 18% in trading on Friday, a day after the e-signature provider reported stronger-than-expected earnings but slashed its full-year billings outlook.
Here’s how the company performed in the fiscal first quarter, compared with estimates from analysts polled by LSEG:
- Earnings per share: 90 cents, adjusted, vs. 81 cents expected
- Revenue: $764 million vs. $748 million expected
Billings, a closely-watched sales metric, came in at $739.6 million in the fiscal first quarter, which ended April 30. That was lower than the $746 million expected by analysts, according to StreetAccount. It also fell short of the company’s own forecast, which guided for billings between $741 million and $751 million.
For the current fiscal year, DocuSign said it expects billings of $3.28 billion to $3.34 billion, down from a range of $3.3 billion to $3.35 billion.
In the first quarter of DocuSign’s 2026 fiscal year, revenue jumped 8% year over year to $764 million. Subscription revenue increased 8% from the same period a year ago to $746.2 million.
DocuSign reported net income of $72.1 million, or 34 cents per share, compared to net income of $33.8 million, or 16 cents per share, a year earlier.
For the fiscal second quarter, the company expects revenue to be between $777 million and $781 million, compared to consensus estimates of $775 million, according to LSEG. For the full fiscal year, DocuSign projected revenue of $3.15 billion to $3.16 billion. Analysts were expecting $3.14 billion, according to LSEG.
The company also announced an additional $1 billion stock buyback, taking its share repurchase plan to $1.4 billion.
DocuSign shares are down more than 16% year to date.
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