The Enormous Risk of Atmospheric Hacking

Bill McKibben
Sweden may soon be the site for a test of geoengineering technology.Photograph by Markus Thomenius / Alamy


February 18, 2021

Sometime in the next two weeks, an independent advisory committee is expected to issue a recommendation on a request from a team of Harvard scientists to fly a balloon from Kiruna, in Sweden’s Lapland region. The team would test a flight platform that might someday be used to inject a sample of aerosols into the stratosphere. Though this initial request is only for a test of a flight platform, a successful run would likely mean more tests, with aerosols of calcium carbonate and sulfates. These particles could hack the planet’s climate, by reflecting some of the sun’s light back out to space before it can reach the ground. It’s an ominous moment in the planet’s history—and one we should back away from for now.

This so-called solar geoengineering is the ultimate, break-the-glass response to the climate crisis. It’s been in the air, so to speak, for a long time (I wrote about it in 1989, in “The End of Nature”), but the fullest account yet comes in my colleague Elizabeth Kolbert’s marvellous new book, “Under a White Sky.” The title acknowledges the fact that this atmospheric hack could change the blue dome above our heads to a milky gray—which should give you some sense of the scale of the intervention. The argument in its favor is that humanity has done so little to address the climate crisis, despite thirty years of scientific warning, that we might have no choice but to follow our injection of CO2 with an injection of sulfate aerosols. Think of it as Narcan, on a global scale. “Geoengineering is not something to do lightly,” Harvard’s Daniel Schrag told Kolbert. “The reason we’re thinking about it is because the real world has dealt us a shitty hand.”


Indeed, it’s possible to imagine how this happens—possible to imagine some moment in the future when it’s in the survival interest of both, say, the Marshall Islands and ExxonMobil, and they possess enough moral and financial clout to send us down this path, one fraught not just with metaphysical danger (a white sky?!) but with enormous practical risk. This man-made equivalent of a permanent cloud of volcanic ash might disrupt the monsoons over Asia; it will definitely allow the oceans to continue acidifying; and, as the climate scientist and geophysicist Raymond Pierrehumbert points out, it gets us ever farther out on a limb, because, if we’re masking increasing carbon with sulfur, we’ll never be able to stop without triggering a period of accelerated warming. “The disastrous consequences of termination shock would grow as we cower year after year under the flimsy stratospheric sunshade,” he wrote, “hoping that technology to suck carbon dioxide out of the atmosphere on a massive scale becomes practical before disaster strikes.” It’s also worth imagining how whoever does engineer the sky will be blamed for every weather disaster henceforth—it’s bad enough trying to deal with the cascade of nonsense about green energy causing the Texas power outages.

It would be stupid to say that we will never need to consider a step this horrible: Kim Stanley Robinson, in his masterly new novel “The Ministry for the Future,” makes it a plot point. After an epic Indian heat wave claims millions of lives, Delhi launches a fleet of aerosol-spewing aircraft to cool the planet. But right now, in the real world, progressing with this kind of work takes the heat off our political systems at precisely the moment—to the month—when they’re finally beginning to get into gear. The United States, the world’s largest economy, has finally assembled the will to tackle global warming: last week’s initial meeting of the federal climate team under Gina McCarthy was a Zoom screenshot of what concentrated power in service of the future might look like. Engineers have provided us with cheap solar and wind power, and with affordable batteries to store that power. This means that, if we want to, as a civilization, we can devote the next decade to an all-out effort to transform our energy system. And the Intergovernmental Panel on Climate Change has said that, if we do—if we cut our emissions forty-five per cent from 2010 levels by 2030—then we have a shot at limiting the temperature rise to the 1.5-degrees-Celsius target set in the Paris accord. Our attention—all our attention—should be on that goal. If we don’t meet it by 2030, then we need to have a serious talk as a species and start assessing our options. That’s the moment for beginning these kinds of tests, not now, when they will become a rallying point for the people and the interests that want to slow the pace in this decade of transformation.

It is especially ironic, for a couple of reasons, that Harvard will do this in Sweden. For one thing, it’s a Swede, Greta Thunberg, who is as responsible as anyone for bringing us to the moment when we might actually pursue a serious course forward to limit emissions. For another, in the face of the climate crisis, Harvard has refused (despite huge support from students, faculty, and alumni) even to join its peers, such as Oxford, Cambridge, and Berkeley, in divesting from fossil-fuel companies. The Harvard Corporation and its Board of Overseers even changed the rules of election to the board, preventing insurgent, climate-defending alumni from electing a majority of the seats.


It seems clear that the thing we need to test first is not aerosol-spewing balloons but our ability as a species to rein ourselves in, and it also seems clear that the next decade is the time for that test. If we fail, then perhaps we deserve to stare pathetically at a white sky.

Passing the Mic

Letitia James is the attorney general of New York, and has emerged as one of the key public officials trying to hold the climate line. In her previous job, as New York City’s public advocate, she helped spur the city’s commitment to divestment. She was a constant thorn in President Trump’s side, challenging his environmental-protections rollbacks in court, and she pursued a civil lawsuit filed by the state alleging that Exxon had hidden the costs of climate change from its investors. A judge ruled against New York in December of 2019, but, given the state’s clout, she will be crucial in the continuing fight to hold the oil companies accountable for climate damage. (Our conversation has been edited for length.)

From your days as public advocate, you’ve been a powerful voice for climate action—one of the first and loudest, for instance, to call for divestment of the city’s pension funds. Where did that passion come from?

I led the charge to divest from fossil fuels because there is nothing prudent about investing in companies that cause so much harm to our people and our planet. After many years, I’m proud to see this finally become reality.

That passion and understanding came from my personal experiences growing up in Brooklyn and then representing my district in public office. I learned early on that the health of our planet is inextricably tied to the health and safety of our communities. But I also learned that the negative impacts of an unhealthy planet are not shared equally—there is a disproportionate impact on communities of color and on our most vulnerable. When I was a City Council member, I met far too many young Black children in my neighborhood who struggled with severe asthma, and this was not the case in predominantly white neighborhoods in New York.

And the science affirms this—predominantly Black and Hispanic communities, especially in New York, are exposed to much more polluted air than white communities are. It’s in these communities where we find the sanitation disposal centers and where we have greater vehicle traffic and pollution.

Protecting the environment and our resources should be a priority for everyone. But the truth is, it’s not just a matter of insuring the next generation inherits a healthy and safe planet—this is about equality and justice, too.  

You fought hard in the case against Exxon. Are these companies, which, by every account, knew about and lied about climate change for decades, really going to escape paying a price for that conduct? What are the next steps for holding them accountable?


From Day One, I have maintained that the American public is entitled to the truth, and through our efforts in court, that’s exactly what they got. For the first time, ExxonMobil was compelled to answer publicly for their internal decisions that misled investors. The oil giant never took seriously the severe economic impact that climate-change regulations would have on the company, contrary to what they were telling the public.

Throughout this case, we laid out how Exxon made materially false, misleading, and confusing representations to the American people about the company’s response to climate-change regulations. Exxon’s inability to tell the truth further underscores the lies that have been sold to the American public for decades. Despite the court’s decision, my office is continuing the fight to insure companies are held responsible for actions that undermine and jeopardize the financial health and safety of Americans across our country, and we will continue to fight to end climate change.

The iron law of climate change—domestically and globally—is that those who did the least to cause it suffer first and worst. How can the justice system reflect that fact here, and is there any discussion among your colleagues around the world about ways to reflect that fact in cross-boundary legal action?


[Top photo: Sweden may soon be the site for a test of geoengineering technology.Photograph by Markus Thomenius / Alamy]