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.
Technology
Meet the 21-year-old helping coders use AI to cheat in Google and other tech job interviews
A person walks past the entrance to a Google building in Dublin, Feb. 15, 2023.
Artur Widak | Anadolu | Getty Images
After landing internship offers from Amazon, Meta and TikTok, computer science student Chungin “Roy” Lee has decided to move to San Francisco.
But he won’t be joining any of those companies.
Instead, Lee will be building his own startup that offers a peculiar service: helping software engineers use artificial intelligence to cheat in their technical job interviews.
“Everyone programs nowadays with the help of AI,” said Lee, a 21-year-old student at Columbia University, which has opened disciplinary proceedings against him, according to documents viewed by CNBC. A Columbia spokesperson said the university doesn’t comment on individual students.
“It doesn’t make sense to have an interview format that assumes you don’t have the use of AI,” Lee said.
Lee is at the forefront of a movement among professional coders who are exploiting the limitations of remote job interviews, popularized during the Covid pandemic, by using AI tools off camera to ensure they give hiring managers the best possible answers.
The hiring process that took hold in the work-from-home era involved candidates interviewing from behind a Zoom screen rather than traveling, sometimes across the country, for on-location interviews, where they could show their coding skills on dry-erase boards.
In late 2022 came the boom in generative AI, with the release of OpenAI’s ChatGPT. Since then, tech companies have laid off tens of thousands of programmers while touting the use of AI to write code. At Google, for example, more than 25% of new code is written by AI, CEO Sundar Pichai told investors in October.
The combination of rapid advancements in AI, mass layoffs of software developers, and a continuing world of remote and hybrid work has created a novel conundrum for recruiters.
The problem has become so prevalent that Pichai suggested during a Google town hall in February that his hiring managers consider returning to in-person job interviews.
Google isn’t the only tech company weighing that idea.
But engineers aren’t slowing down.
Lee has turned his cheating into a business. His company, Interview Coder, markets itself as a service that helps software developers cheat during job interviews. The internship offers that he landed are the proof he uses to show that his technology works.
AI assistants for virtual interviews can provide written code, make code improvements, and generate detailed explanations of results that candidates can read. The AI tools all work quickly, which is helpful for timed interviews.
Hiring managers are venting their frustrations on social media over the rise of AI cheaters, saying that those who get caught are eliminated from contention. Interviewers say they’re exhausted from having to discern whether candidates are using their own skills or relying on AI.
‘Invisible’ help
The cheating tools rely on generative AI models to provide software engineers with real-time answers to coding problems as they’re presented during interviews. The AI analyzes both written and oral questions and instantaneously generates code. The widgets can also provide the cheaters with explanations for the solutions that they can use in the interview.
The tools’ most valuable feature, however, might be their secrecy. Interview Coder is invisible to the interviewer.
While candidates are using technology to cheat, employers are observing their behavior during interviews to try to catch them. Interviewers have learned to look for eyes wandering to the side, the reflection of other apps visible on candidates’ glasses, and answers that sound rehearsed or don’t match questions, among other clues.
Perhaps the biggest tell is a simple “Hmm.”
Hiring managers said they’ve noticed that many candidates use the ubiquitous sound to buy themselves time while waiting for their AI tools to finish their work.
“I’ll hear a pause, then ‘Hmm,’ and all of a sudden, it’s the perfect answer,” said Anna Spearman, founder of Techie Staffing, an agency that helps companies fill technical roles. “There have also been instances where the code looked OK, but they couldn’t describe how they came to the conclusion.”
Henry Kirk, a software developer and co-founder of Studio.init in New York, said this type of cheating used to be easy to catch.
“But now it’s harder to detect,” said Kirk. He said the technology has gotten smart enough to present the answers in a place that doesn’t require users to move their eyes.
“The eye movement used to be the biggest giveaway,” Kirk said.
Interview Coder’s website says its virtual interview tool is immune to screen detection features that are available to companies on services such as Zoom and Google Meet. Lee markets his product as being webcam-proof.
When Kirk hosted a virtual coding challenge for an engineering job he was looking to fill in June, 700 people applied, he said. Kirk recorded the process of the first interview round. He was looking to see if any candidates were cheating in ways that included using results from large language models.
“More than 50% of them cheated,” he said.
AI cheating tools have improved so much over the last year that they’ve become nearly undetectable, experts said. Other than Lee’s Interview Coder, software engineers can also use programs such as Leetcode Wizard or ChatGPT.
Kirk said his startup is considering moving to in-person interviews, though he knows that potentially limits the talent pool.
“The problem is now I don’t trust the results as much,” Kirk said. “I don’t know what else to do other than on-site.”
Google CEO Sundar Pichai during an event at the Google for Startups Campus in Warsaw, Poland, Feb. 13, 2025.
Omar Marques | Anadolu | Getty Images
Back to the Googleplex
It’s become a big topic at Google, and one Pichai addressed in February at an internal town hall meeting, where executives read questions and comments that were submitted by employees and summarized by AI, according to an audio recording that was reviewed by CNBC.
One question asked of management was, “Can we get onsite job interviews back?”
“There are many email threads about this topic,” the question said. “If budget is constraint, can we get the candidates to an office or environment we can control?”
Pichai turned to Brian Ong, Google’s vice president of recruiting, who was joining through a virtual livestream.
“Brian, do we do hybrid?” Pichai asked.
Ong said candidates and Google employees have said they prefer virtual job interviews because scheduling a video call is easier than finding a time to meet in available conference rooms. The virtual interview process is about two weeks faster, he added.
He said interviewers are instructed to probe candidates on their answers as a way to decipher whether they actually know what they’re talking about.
“We definitely have more work to do to integrate how AI is now more prevalent in the interview process,” said Ong. He said his recruiting organization is working with Google’s software engineer steering committee to figure out how the company can refine its interviewing process.
“Given we all work hybrid, I think it’s worth thinking about some fraction of the interviews being in person,” Pichai responded. “I think it’ll help both the candidates understand Google’s culture and I think it’s good for both sides.”
Ong said it’s also an issue “all of our other competitor companies are looking at.”
A Google spokesperson declined to comment beyond what was said at the meeting.
Other companies have already shifted their hiring practices to account for AI cheating.
Deloitte reinstated in-person interviews for its U.K. graduate program, according to a September report.
Anthropic, the maker of AI chatbot Claude, issued new guidance in its job applications in February, asking candidates not to use AI assistants during the hiring process.
“While we encourage people to use AI systems during their role to help them work faster and more effectively, please do not use AI assistants during the application process,” the new policy says. “We want to understand your personal interest in Anthropic without mediation through an AI system, and we also want to evaluate your non-AI-assisted communication skills. Please indicate ‘Yes’ if you have read and agree.”
Amazon is also taking steps to combat AI cheating.
The company asks that candidates acknowledge that they won’t use unauthorized tools during the interview or assessment process, spokesperson Margaret Callahan told CNBC.
Chungin “Roy” Lee, a 21-year-old student at Columbia University, is the founder of Interview Coder, a startup that makes software to help computer programmers cheat in job interviews with the help of AI.
Courtesy of Chungin Lee
‘F*ck Leetcode’
If you visit InterviewCoder.co, the first thing that greets you is large gray type that reads “F*ck Leetcode.”
Leetcode is the program used by many tech companies to evaluate software engineers for technical roles. Tech companies such as Meta, Google and Amazon use it to keep tabs on the thousands of job applicants they evaluate.
“Every time I mention interviews, I get frustrated comments about Leetcode,” wrote Ryan Peterman, a software engineer at Meta, in a newsletter posted on Substack in December. Peterman said Leetcode problems are purposely designed to be much harder than what software engineers would do on the job. Leetcode is the best tool companies have to filter hundreds of applicants, Peterman wrote.
Coders said they hate Leetcode because it emphasizes algorithmic problem-solving and asks applicants to solve riddles and puzzles that seem irrelevant to the job, according to those CNBC spoke with as well as comments CNBC found from engineers across various social media platforms. Another downside is that it sometimes requires hours of work that may not result in a job offer or advancement, they said.
Leetcode served as Lee’s inspiration for building Interview Coder, he said. With the help of AI, he said, he created the service in less than a week.
“I thought I wanted to work at a big tech company and spent 600 hours practicing for Leetcode,” Lee said. “It made me miserable, and I almost stopped programming because of how much I didn’t like it.”
Lee’s social media posts are filled with comments from other programmers expressing similar frustrations.
“Legend,” several comments said in response to some of his X posts. Others said they enjoyed him “f—ing with big tech.”
Rival software Leetcode Wizard was also inspired by distaste for Leetcode.
Isabel De Vries, Leetcode Wizard’s head of marketing, told CNBC in a statement that Leetcode-style interviews fail to accurately measure engineering skills and fail to reflect actual daily engineering work.
“Our product originates from the same frustrations many of our users are having,” De Vries said.
Leetcode did not respond to CNBC’s request for comment.
Henry Kirk, a software developer and co-founder of Studio.init in New York, is considering moving job interviews to be on site in response to software engineers using AI to cheat in virtual interviews.
Photo by Krista Schlueter for Inc. Magazine
When Kirk, of Studio.init, posted on LinkedIn in February to vent about his frustrations with AI cheating, he received nearly 200 comments. But most argued that employers should allow candidates to use AI in the hiring process.
“Even the SAT lets you use a calculator,” said one comment. “I think you just make it harder to succeed on purpose when in the real world Google and gpt will always be at my fingertips.”
Lee promotes Interview Coder as being “invisible to all screen-recording softwares.” To prove its effectiveness, he recorded himself passing an Amazon interview and posted the video on YouTube. Amazon and the other companies that had made offers to Lee then rescinded them.
Lee got hundreds of comments praising the video, which YouTube removed after CNBC reached out to Amazon and Google for this story. YouTube cited a “copyright claim” by Amazon as the reason for removing the video.
“I as an interviewer am so annoyed by him but as a candidate also adore him,” former Meta staff engineer Yangshun Tay, co-founder of startup GreatFrontEnd, wrote in a LinkedIn post about Lee and his video. “Cheating isn’t right, but oh god I am so tired of these stupid algorithm interviews.”
After YouTube removed the video, Lee uploaded it once again.
Cheating as a service
Lee said he never planned to work at Amazon, Meta or TikTok. He said he wanted to show others just how easy it is to game Leetcode and force companies to find a better alternative.
And, he said, he’s making money in the process.
Interview Coder is available as a subscription for $60 a month. Lee said the company is on track to hit $1 million in annual recurring revenue by mid-May.
He recently hired the internet influencers who go by the name “Costco Guys” to make a video marketing his software.
“If you’re struggling to pass your Leetcode interviews and want to get a job at a big tech company, you’ve got to take a look at Interviewcoder.co to pass your interview,” the Costco Guys say in their video. “Because Interview Coder gets five big booms! Boom! Boom! Boom! Boom! Boooooom!”
Leetcode Wizard bills itself on its website as “The #1 AI-powered coding interview cheating app” and “The perfect tool for achieving a ‘Strong Hire’ result in any coding interview and landing your dream job at any FAANG company.” Leetcode Wizard charges 49 euros ($53) a month for a “Pro” subscription.
More than 16,000 people have used the app, and “several hundred” people have told Leetcode Wizard that they received offers thanks to the software, the company told CNBC.
“Our product will have succeeded once we can shut it down, when leetcode interviews are a thing of the past,” De Vries said.
Lee said he’s moving from New York to San Francisco in March to continue building Interview Coder and start working on his next company.
Kirk said he understands software engineers’ frustration with Leetcode and the tech industry. He’s had to use Leetcode numerous times throughout his career, and he was laid off by Google in 2023. He now wants to help out-of-work engineers get jobs.
But he remains worried that AI cheating will persist.
“We need to make sure they know their stuff because these tools still make mistakes,” Kirk said.
Half of companies currently use AI in the hiring process, and 68% will by the end of 2025, according to an October survey commissioned by ResumeBuilder.com.
Lee said that if companies want to bill themselves as AI-first, they should encourage its use by candidates.
Asked if he worries about software engineers losing the trust of the tech industry, Lee paused.
“Hmm,” he mumbled.
“My reaction to that is any company that is slow to respond to market changes will get hurt and that’s the fault of the company,” Lee said. “If there are better tools, then it’s their fault for not resorting to the better alternative to exist. I don’t feel guilty at all for not catering to a company’s inability to adapt.”
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