For the past handful of years, the Harvard professor David Keith has been sketching this vision: Ten Gulfstream jets, outfitted with special engines that allow them to fly safely around the stratosphere at an altitude of 70,000 feet, take off from a runway near the Equator. Their cargo contains thousands of pounds of a chemical compound — liquid sulfur, let’s suppose — that can be sprayed as a gas from the aircraft. It is not a one particular-time occasion the flights take spot all through the year, dispersing a load that amounts to 25,000 tons. If factors go right, the gas converts to an aerosol of particles that remain aloft and scatter sunlight for two years. The payoff? A slowing of the earth’s warming — for as long as the Gulfstream flights continue.

Keith argues that such a project, usually recognized as solar geoengineering, is technologically feasible and — with a back-of-the-envelope expense of below $ 1 billion annually — ought to be fairly low-cost from a expense-advantage viewpoint, considering the economic damages potentially forestalled: It may well do good for a world unable to cut carbon-dioxide emissions sufficient to stop further temperature increases later this century.

What surprised me, then, as Keith paced around his Harvard workplace one particular morning in early March, was his listing all the motives humans may well not want to hack the environment. “Actually, I’m writing a paper on this appropriate now,” he stated. Most of his thoughts have been related to the possible dangers of attempting to engineer our way out of a climate issue of nearly unimaginable scientific, political and moral complexity. Solar geoengineering might lead to what some economists get in touch with “lock-in,” referring to the momentum that a new technologies, even 1 with critical flaws, can assume soon after it gains a foothold in the market. The qwerty keyboard is 1 typically cited instance the internal combustion engine is yet another. Once we commence placing sulfate particles in the atmosphere, he mused, would we truly be able to quit?

An additional concern, he said, is “just the ethics about messing with nature.” Tall, wiry and kinetic, with thinning hair and a thick beard that gives him the look of the backcountry skier he is, Keith proudly showed me the framed badge that his father, a biologist, wore when he attended the landmark United Nations Conference on the Human Atmosphere in Stockholm in 1972. Now 53, Keith has taken much more wilderness trips — hiking, rock climbing, canoeing — than he can appropriately recall, and for their recent honeymoon, he and his wife have been dropped off by helicopter 60 miles from the nearest road in northern British Columbia. “It was really rainy,” he told me, “and that ended up creating it even better.” So the prospect of intentionally altering the climate, he confessed, is not just unpleasant — “it initially struck me as nuts.”

It nevertheless strikes him as a moral hazard, to use a term he borrows from economics. A planet cooled by an umbrella of aerosol particles — an umbrella that performs by reflecting back into space, say, 1 percent of the sun’s incoming energy — may possibly give societies significantly less incentive to adopt greener technologies and radically reduce carbon emissions. That would be disastrous, Keith said. The entire point of geoengineering is not to give us license to neglect about the buildup of CO₂. It’s to lessen the ill effects of the buildup and give us time to transition to cleaner power.

Beyond these conceivable dangers, although, a more fundamental issue lurks: Solar geoengineering basically may well not function. It has been a topic of intense debate amongst climate scientists for roughly a decade. But most of what we know about its potential effects derives from either laptop simulations or research on volcanic eruptions like that of Mount Pinatubo in 1991, which generated millions of tons of sunlight-scattering particulates and may have cooled the planet by as significantly as .5 degrees Celsius, or almost 1 degree Fahrenheit. The lack of assistance for solar geoengineering’s efficacy informs Keith’s pondering about what we ought to do next. Actively tinkering with our atmosphere — fueling up the Gulfstream jets and trying to cool things down — is not something he intends to try anytime quickly, if ever. But conducting study is another matter.

A decade ago, when Keith was among the handful of American scientists to advocate beginning a geoengineering investigation program, he was typically treated at science conferences as an outlier. “People would sort of inch away or, actually, inform me I shouldn’t be undertaking this,” he stated. Geoengineering was observed as a scientific taboo and Keith its dark visionary. “The preconception was that I was some kind of Dr. Strangelove figure,” he told me — “which I didn’t like.”

Attitudes appear to have changed more than the previous few years, at least in part since of the continuing academic debates and laptop-modeling research. The National Academy of Sciences endorsed the pursuit of solar geoengineering investigation in 2015, a stance also taken in a later report by the Obama administration. A few influential environmental groups, like the Natural Sources Defense Council and the Environmental Defense Fund, now favor investigation.

In the meantime, Keith’s personal perform at Harvard has progressed. This month, he is assisting to begin Harvard’s Solar Geoengineering Research Program, a broad endeavor that starts with $ 7 million in funding and intends to reach $ 20 million over seven years. One backer is the Hewlett Foundation another is Bill Gates, whom Keith frequently advises on climate change. Keith is arranging to conduct a field experiment early subsequent year by placing particles into the stratosphere more than Tucson.

The new Harvard system is not merely intent on receiving its concepts out of the lab and into the field, even though a large share of its income will also be directed to physical and social scientists at the university, who will evaluate solar geoengineering’s environmental dangers — and be prepared to challenge its ethics and practicality. Keith told me, “It’s actually essential that we have a huge chunk of the study go to groups whose job will be to uncover all the ways that it won’t function.” In other words, the technology that Keith has extended believed could aid us ease our predicament — “the nuclear option” for climate, as a single opponent described it to me, to be regarded only when all else has failed — will finally be investigated to see whether or not it is a reasonable notion. At the same time, it will be examined below the premise that it might in reality be a very, quite negative 1.

Climate alter currently presents a demoralizing array of challenges — melting ice sheets and species extinctions — but the ultimate severity of its impacts depends tremendously on how drastically technologies and societies can adjust over the next few decades. The development of solar and wind energy in recent years, along with an apparent reduce in coal use, recommend that the worldwide community will succeed in curtailing CO₂ emissions. Nonetheless, that may possibly not take place practically rapidly sufficient to avert some unsafe consequences. As Keith likes to point out, basically reducing emissions doesn’t reverse international warming. In reality, even if annual worldwide CO₂ emissions reduce somewhat, the total atmospheric CO₂ may possibly continue to improve, due to the fact the gas is so slow to dissipate. We could nevertheless be living with damaging amounts of atmospheric carbon dioxide a half-century from now, with calamitous repercussions. The final time atmospheric CO₂ levels have been as elevated as they are today, 3 million years ago, sea levels had been most likely 45 feet higher, and giant camels roamed above the Arctic Circle.

Lately, I met with Daniel Schrag, who is the head of the Harvard University Center for the Environment, an interdisciplinary teaching and investigation department. Schrag, who helped recruit Keith to Harvard, painted a bleak picture of our odds of maintaining global temperatures from rising beyond levels deemed protected by numerous climate scientists. When you evaluate the time scales involved in really switching our energy systems to cleaner fuels, Schrag told me, “the truly depressing factor is you start off to comprehend why any of these kinds of projections — for 2030 or 2050 — are absurd.” He went on: “Are they impossible? No. I want to give people hope, too. I’d really like to make this come about. And we have produced a lot of progress on some factors, on solar, on wind. But the reality is we haven’t even started carrying out the tough stuff.”

Schrag described any type of geoengineering as “at very best an imperfect resolution that is operationally really difficult.” However to Schrag and Keith, the political and technical difficulties associated with a rapid transition to a zero-carbon-emissions globe make it sensible to look into geoengineering study. There occurs to be a number of various plans for how to actually do it, even so — which includes the fantastical (pumping seawater onto Antarctica to combat sea-level rise) and the impractical (fertilizing oceans with iron to foster the development of algae, which would absorb far more CO₂). Some proposals involve taking carbon out of the air, making use of either immense plant farms or absorption machines. (Keith is involved with such sequestration technologies, which faces important hurdles in terms of expense and feasibility.) Yet another achievable method would inject salt crystals into clouds over the ocean to brighten them and cool targeted regions, like the dying Excellent Barrier Reef. Nevertheless, the feeling amongst Keith and his colleagues is that aerosols sprayed into the atmosphere may be the most economically and technologically viable approach of all — and may well yield the most powerful international impact.

It is not a new thought. In 2000, Keith published a long academic paper on the history of climate and climate modification, noting that an Institute of Rainmaking was established in Leningrad in 1932 and that American engineers began a cloud-seeding campaign in Vietnam a couple of decades later. A report issued in 1965 by President Lyndon B. Johnson’s administration named attention to the dangers of growing concentrations of CO₂ and, anticipating Keith’s analysis, speculated that a logical response may possibly be to alter the albedo, or reflectivity, of the earth. To Keith’s knowledge, though, there have been only two actual field experiments so far. 1, by a Russian scientist in 2009, released aerosols into the lower atmosphere by way of helicopter and seems to have generated no beneficial data. “It was a stunt,” Keith says. Yet another was a modest attempt at cloud brightening a couple of years ago by a group at the Scripps Institution of Oceanography at the University of California, San Diego.

Downstairs from Keith’s Harvard office, there is a lab cluttered with students fiddling with pipettes and arcane scientific instruments. When I visited in early March, Zhen Dai, a graduate student who performs with Keith, was engaged with a tabletop apparatus, a maze of tubes and pumps and sensors, meant to study how chemical compounds interact with the stratosphere. For the moment, Keith’s group is leaning toward beginning its field experiments with ice crystals and calcium carbonate — limestone — that has been milled to particles a half-micron in diameter, or significantly less than 1/100th the width of a human hair. They might sooner or later try a sulfur compound also. The experiment is called Scopex, which stands for Stratospheric Controlled Perturbation Experiment. An instrument that can disperse an aerosol of particles — say, many ounces of limestone dust — will be housed in a gondola that hangs beneath a balloon that ascends to 70,000 feet. The entire custom-built contraption, whose two modest propellers will be steered from the ground, will also incorporate a assortment of sensors to gather data on any aerosol plume. Keith’s group will measure the sunlight-scattering properties of the plume and evaluate how its particles interact with atmospheric gases, particularly ozone. The resulting data will be used by laptop models to try to predict bigger-scale effects.

But whether a scientist must be deliberately placing foreign substances into the atmosphere, even for a modest experiment like this, is a delicate question. There is also the difficulty of deciding on how large the atmospheric plumes should get. When does an experiment turn into an actual trial run? Ultimately, how will the scientists know if geoengineering genuinely functions with out scaling it up all the way?

Keith cites precedents for his considering: a organization that scatters cremation ashes from a high-altitude balloon, and jet engines, whose exhaust contains sulfates. But the crux of the difficulty that Harvard’s Solar Geoengineering Analysis System wrestles with is intentionality. Frank Keutsch, a professor of atmospheric sciences at Harvard who is designing and operating the Scopex experiments with Keith, told me: “This effort with David is really diverse from all my other operate, simply because for those other field experiments, we’ve attempted to measure the atmosphere and appear at processes that are currently there. You’re not truly altering nature.” But in this case, Keutsch agrees, they will be.

Throughout one particular of our conversations, Keith recommended that I attempt to flip my pondering for a moment. “What if humanity had never ever gotten into fossil fuels,” he posed, “and the world had gone straight to producing energy from solar or wind energy?” But then, he added, what if in this imaginary cleaner planet there was a big natural seep of a heat-trapping gas from within the earth? Such events have occurred before. “It would have all the same consequences that we’re worried about now, except that it is not us carrying out the CO₂ emissions,” Keith mentioned. In that case, the reaction to making use of geoengineering to cool the planet might be 1 of relief and enthusiasm.

In other words, decoupling mankind’s actions — the “sin,” as Keith place it, of burning fossil fuels — from our present dilemma can demonstrate the worth of climate intervention. “No matter what, if we emit CO₂, we are hurting future generations,” Keith stated. “And it may possibly or may not be accurate that carrying out some solar geo would over all be a wise thing to do, but we don’t know but. That’s the cause to do study.”

There are risks, undeniably — some tiny, other folks potentially massive and terrifying. David Santillo, a senior scientist at Greenpeace, told me that some modeling studies suggest that placing aerosols in the atmosphere, which may well alter local climates and rain patterns and would certainly influence the amount of sunlight hitting the earth, could have a important impact on biodiversity. “There’s a lot a lot more we can do in theoretical terms and in modeling terms,” Santillo said of the Harvard experiments, “before any person must go out and do this sort of proof-of-notion perform.” Alan Robock, a professor of atmospheric sciences at Rutgers, has compiled an exhaustive list of feasible dangers. He thinks that tiny-scale projects like the Scopex experiment could be valuable, but that we don’t know the impacts of huge-scale geoengineering on agriculture or regardless of whether it may deplete the ozone layer (as volcanic eruptions do). Robock’s list goes on from there: Solar geoengineering would possibly minimize solar-electricity generation. It would do nothing at all to minimize the rising acidification of the oceans, triggered by seawater absorbing carbon dioxide. A actual prospect exists, also, that if solar geoengineering efforts were to cease abruptly for any cause, the globe could face a fast warming even much more dangerous than what’s happening now — maybe too quick for any ecological adaptation.

Keith is properly aware of Robock’s issues. He also makes the distinction that advocating analysis is not the exact same as advocating geoengineering. But the line can blur. Keith struck me as obtaining a fair measure of optimism that his analysis can yield insights into materials and processes that can minimize the impacts of worldwide warming even though averting large dangers. For instance, he is currently encouraged by laptop models that suggest the Arctic ice cap, which has shrunk this year to the smallest size observed for the duration of the satellite era, could regrow under cooler situations brought on by light-scattering aerosols. He also believes that the most widespread accusation directed against geoengineering — that it may disrupt precipitation patterns and lead to widespread droughts — will prove largely unfounded.

But Keith is not educated as an atmospheric scientist he’s a hands-on physicist-engineer who likes to take machinery apart. There are deep unknowns here. Keutsch, for a single, seems uncertain about what he will discover when the group truly tries spraying particulates high above the earth. The reduction of sunlight could adversely have an effect on the earth’s water cycle, for example. “It truly is unclear to me if this strategy is feasible,” he says, “and at this point we know far too little about the dangers. But if we want to know no matter whether it operates, we have to find out.”

Lastly, what if some thing goes wrong either in investigation or in deployment? David Battisti, an atmospheric scientist at the University of Washington, told me, “It’s not obvious to me that we can minimize the uncertainty to anywhere close to a tolerable level — that is, to the level that there will not be unintended consequences that are really critical.” Whilst Battisti believed Keith’s tiny Scopex experiment posed little danger — “The atmosphere will restore itself,” he mentioned — he noted that the entire point of the Harvard researchers’ perform is to establish regardless of whether solar geoengineering could be carried out “forever,” on a large-scale, round-the-clock basis. When I asked Battisti if he had troubles with going deeper into geoengineering study, as opposed to geoengineering itself, he stated: “Name a technologies humans have created that they haven’t used. I cannot consider of any. So we can work on this for certain. But we are in this dilemma: Once we do create this technologies, it will be tempting to use it.”

Suppose Keith’s analysis shows that solar geoengineering performs. What then? The world would need to agree where to set the worldwide thermostat. If there is no consensus, could developed nations impose a geoengineering regimen on poorer nations? On the second point, if this technology functions, it would arguably be unethical not to use it, since the world’s poorest populations, facing drought and increasing seas, may possibly endure the worst effects of a changing climate.

In recent months, a group below the auspices of the Carnegie Council in New York, led by Janos Pasztor, a former United Nations climate official, has begun to perform via the thorny international concerns of governance and ethics. Pasztor told me that this work will most likely take 4 years. And it is not lost on him — or anybody I spoke with in Keith’s Harvard group — that the notion of engineering our atmosphere is taking hold as we are contemplating the engineering of ourselves by means of novel gene-editing technologies. “They each have an effect on shaping the pathway where human beings are now and exactly where will they be,” says Sheila Jasanoff, a professor of science and technology studies at Harvard who often collaborates with Keith. Jasanoff also points out that each technology potentially enables rogue agents to act without societal consent.

This is a widespread concern. We might reach a point at which some nations pursue geoengineering, and nothing at all — neither expenses nor treaties nor current technologies — can quit them. Pasztor sketched out yet another possibility to me: “You could even have a nightmare scenario, exactly where a country decides to do geoengineering and an additional nation decides to do counter-geoengineering.” Such a countermeasure could take the form of an intentional release of a heat-trapping gas far much more potent than CO₂, like a hydrochlorofluorocarbon. 1 of Schrag’s primary concerns, in fact, is that geoengineering a lower global temperature may possibly preserve ecosystems and limit sea-level rise although producing irreconcilable geopolitical frictions. “One point I can’t figure out,” he told me, “is how do you safeguard the Greenland ice sheet and still have Russia have access to its northern ports, which they genuinely like?” Either Greenland and Siberia will melt, or maybe both can stay frozen. You most likely can’t split the difference.

For the moment, and perhaps for 10 or 20 years much more, these are mere hypotheticals. But the impacts of climate modify have been once hypotheticals, as well. Now they’ve grow to be possibilities and probabilities. And but, as Tom Ackerman, an atmospheric scientist at the University of Washington, stated at a current discussion among policy makers that I attended in Washington: “We are undertaking an experiment now that we don’t comprehend.” He was not talking about geoengineering he was observing that the uncertainty about the prospective dangers of geoengineering can obscure the truth that there is uncertainty, too, about the escalating disasters that might quickly result from climate alter.

His comment reminded me of a claim made more than a half-century ago, lengthy prior to the buildup of CO₂ in the atmosphere had become the central environmental and financial issue of our time. Two scientists, Roger Revelle and Hans Suess, wrote in a scientific paper, “Human beings are now carrying out a massive-scale geophysical experiment of a type that could not have occurred in the past nor be reproduced in the future.”

If anything could sway a fence-sitter to think about regardless of whether geoengineering analysis tends to make sense, probably it is this. The fact is, we are living by means of a test already.