海角大神

The idea of blotting out the sun, whether floated by Fr茅d茅ric Bastiat or Montgomery Burns, has long stood as a metaphor for human arrogance.

But today, as the planet approaches critical temperature thresholds, some observers are now saying that reducing the amount of sunlight, and therefore heat, that reaches the Earth鈥檚 surface, is not just technologically feasible, but also necessary to avoid catastrophe.

The latest report from the United Nations鈥� Intergovernmental Panel on Climate Change, with its warnings of worsening water shortages, heat waves, and rising seas, along with the catastrophic damages from extreme weather events like hurricanes Michael and Florence, have increased some of the buzz around geoengineering: deliberate large-scale technical interference into the Earth鈥檚 climate system.

At this point, the discussion is largely theoretical. But as it gets more pointed and specific, it also raises a host of ethical questions. Nearly every weather event, from a tornado to a windless day, produces winners and losers. But what happens when those winners and losers arise from deliberate policies?

鈥淚s this a problem that鈥檚 so new that we have to come up with completely new ethical tools to even understand it?鈥� asks Forrest Clingerman, professor of religion and philosophy at Ohio Northern University and co-editor of the 2016 book, 鈥淭heological and Ethical Perspectives on Climate Engineering.鈥� 鈥淚s this a technology that raises similar questions ethically as some other technologies that we鈥檝e seen in the past,鈥� he asks. 鈥淥r is this fundamentally new?鈥�

The most common form of geoengineering that gets discussed is stratospheric aerosol injection, which would use artillery or aircraft to deposit reflective particles into the upper atmosphere, about 12 miles up. These particles 鈥� scientists have proposed everything from sulfur dioxide to calcium carbonate to even diamonds 鈥� would either directly or indirectly redirect a portion of the sunlight striking them back into space. In theory, this additional reflectivity would make the surface below a little cooler than it otherwise would be: enveloping the planet in a giant reflective veil.

But that sort of solar geoengineering intentionally creates a layer of pollution in the atmosphere, and is also likely to cause climate problems in certain places,聽. And it doesn鈥檛 address the fundamental underlying problem of too much carbon dioxide in the atmosphere.

Scientists have also floated other ideas, from building a giant, space-based sunshade to fertilizing the oceans with iron to promote plankton growth. And at a far more accepted 鈥� and less theoretical 鈥� level, some forms of聽carbon removal technologies聽are also a form of geoengineering. Carbon removal has fewer ethical pitfalls, however, and as it has become a bigger part of the discussion, the geoengineering label has largely been dropped.

Scientists who think such tools at least warrant investigation note that humans are already playing a massive role in the Earth鈥檚 climate, albeit unintentionally.

鈥淭here鈥檚 a strain in environmentalism that doesn鈥檛 want humans to interfere in nature, which is something I understand and empathize with,鈥� says Holly Jean Buck, a fellow at the Institute of the Environment and Sustainability at the University of California, Los Angeles. 鈥淭he problem is, though, that we already have to such a degree that some degree of repair and restoration is needed.鈥�

In search of the greatest good

Trying to affect weather patterns, at least at a local scale, isn鈥檛 terribly new. Cloud seeding to mitigate drought has been used for more than 75 years. And back in 1947, the US military attempted to break up a hurricane that was stalled off Florida鈥檚 coast, by dumping dry ice into the clouds. The day after a pilot did just that, the hurricane changed direction and hit the Georgia coast. It鈥檚 still unclear whether the dry ice precipitated the change in direction, but the public blamed the government, and Project Cirrus, as it was called, was canceled.

Today, discussion of large-scale, whole-planet climate manipulation brings up the same questions of winners and losers. A聽聽published in the journal Nature Communications suggests that stratospheric aerosol injection could potentially mitigate hurricane activity 鈥� but that if it was applied in the Northern Hemisphere, it might enhance tropical cyclone activity in the Southern Hemisphere, and vice versa.

鈥淲e鈥檝e been unintentionally geoengineering for centuries. But there does seem to be something fundamentally different between accidentally doing something and saying, 鈥極K, now we鈥檙e going to intentionally do this,鈥� 鈥� says Professor Clingerman. 鈥淐limate change generally speaking is something that is global. And it鈥檚 also intergenerational. That complicates any utilitarian calculus.鈥�

But others say that we may get to a point where there鈥檚 little choice, and where the ethical consideration is what produces the greatest good for the greatest number of people.

鈥淯tilitarianism is probably the only plausible approach to thinking about it,鈥� says Martin Bunzl, a philosophy of science professor at Rutgers University and director of the Initiative on Climate and Social Policy.

Professor Bunzl says the bigger concerns he has are with the uncertainties. It鈥檚 impossible to experiment in a small way with large-scale geoengineering, so scientists would have to rely on computer modeling and hypotheses, without any controlled rigorous testing.

鈥淓ven if you do it at a global level and, say, ramp up the dosage to try and see the effects, it would take far far too long to distinguish between noise and signal,鈥� says Bunzl. 鈥淪o you鈥檙e really put in the position of having to go to something like full insertion.鈥�

But he says he thinks it may well get to the point where we鈥檝e failed at other climate mitigation strategies and the risks of geoengineering seem worth it. And, if computer modeling significantly improves over the next few decades, it could allow us to have a more informed discussion about just what those risks are.

鈥淚 think that would strongly affect the way this debate has gone, because a lot of this debate has less been on the ethics of one particular population bearing the cost of this, but on the unknowns about the effects,鈥� Bunzl says.

At this point, the discussion of solar geoengineering is still pretty theoretical, with scientists just beginning to have a handle on how it might work, as well as how it would affect complex weather and atmospheric patterns.

But as climate impacts are increasingly felt, its place in the international debate is growing.

鈥淭here鈥檚 no question that solar geoengineering is a terrifying prospect. It involves changing the amount and type of sunlight coming down to the whole Earth,鈥� says Dr. Buck. 鈥淭here鈥檚 not another Earth where you could do it differently and see what happens, or see what happens in the absence of it.... But the fact of the matter is that maybe there鈥檚 a scenario where climate change is causing mass suffering and perhaps playing a factor in conflicts. There might be a scenario in which solar geoengineering is better than not having it. I really hope we never have to face that choice.鈥�