Unfortunately, ENMOD is, at present, stuck in the Cold War. Created in 1978, largely in response to U.S. cloud-seeding efforts intended to worsen the Vietnamese monsoon, ENMOD's military orientation is clear. But ENMOD is positively chirpy about "peaceful" environmental modification. So geoengineering, which is being sold as an altruistic research program, wouldn't fit the bill unless someone could prove hostile intent. One worry, of course, is that climate change might provide convenient cover for one country to wreck another's economy with subtly directed geoengineering. ENMOD—if awakened—would cover those sorts of transgressions already. But the treaty-makers need to learn two post-Cold War lessons: Overt hostility is not the only cause of environmental disaster, and even those with good intentions should clean up after themselves.
Modify the treaty's "peaceful purposes" language to hold geoengineers or their funders responsible for any damage they might do, and ENMOD's chirp starts to sound more attuned to the dangers of our time. A beefed-up version of the treaty would offer developing countries enough protection against geoengineering gone wrong that they could begin the key conversation—whether their shared values would permit geoengineering at all. But many challenges would remain. For example, geoengineers in search of grants could make a strong case that the new ENMOD would amount to a blanket ban on their work, since no one would want to accept financial liability for stopping the monsoon. Even if someone did agree to foot the bill, it would be hard to collect fines, no matter how bad the calamity. Observing and explaining large-scale climate trends is possible, but specific attribution—showing that a certain drought in China was caused, even in part, by sun-dimming sulfates peacefully lofted from Qatar—is vanishingly difficult.
There is room for creativity here. An updated version of ENMOD could require anyone funding a geoengineering project to post an environmental assurance bond (PDF) big enough to pay for a reasonable-worst-case catastrophe. ("Sulfate dust blows up the planet" wouldn't count, but stopping the monsoon might.) The people issuing and applying for the bonds might well have unique insights about potential risks, and if they were forced to have skin in the game, they could feel some pressure to use them.
Policy wonks, of course, would want a treaty with much more: a decision-making process that could bridge the gap between rich and poor nations; a firm, yet fair, distinction between research and deployment; mandatory implementation of yet-to-be-designed domestic laws that take high-impact geoengineering out of the private sector; seats on a black-tie cruise with Bill Gates to survey the results of his cloud-brightening experiments; an ENMOD Squad that roamed the world investigating geoengineering projects; and a live band playing soothing remixes of the 007 theme at all treaty-related meetings.
But updating ENMOD's "peaceful purposes" language to require geoengineers to have skin in the game is the core principle. When scientists, businesses, or countries aren't put on the hook for the bad outcomes of their actions, the injustices that result may never get sorted out—because the responsibility wasn't clear in advance. An environmental assurance bond would help make it clear. This time, the stakes are very high. No one, especially in the developing world, should give the geoengineering community a pass based merely on its good intentions, with which the road to a dim and dusty planetary hell might be paved.
Of course, since even an ideal ENMOD probably wouldn't extend to coal plants and automobile exhaust pipes, it would, in a sense, be unfair to geoengineers. The unintentional climate-hackers who are warming the planet—all of us, though some of us more than others—wouldn't be held responsible for the damage that we're doing, but intentional geoengineers would be held responsible for any problems caused by their attempts to correct it. Still, some responsibility is better than none.
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