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Geo-Engineering Could Save the Planet … and in the Process Sacrifice the World

Having unintentionally warmed the planet, we may have little choice but to intentionally cool it back down. But at what cost?

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"There are no reasons not to have a research program," Thernstrom said to me. "There is no advantage to ignorance on geo-engineering."

Research alone seems harmless enough. If caution warns against the consequences of jury-rigging the atmosphere, prudence argues that it's wise to have a backup plan in case of climate disaster. As Ken Caldeira put it, a coastal city would want to have dykes to protect itself against storm surges and sea level rise. But that doesn't mean city leaders wouldn't also have an evacuation plan in case the dykes failed. Geo-engineering is that evacuation plan.

Only in this case, the evacuation would be a retreat from the entire world, the planet as we have always known it. If we spray tons of sulfur into the air and, as scientists expect, it turns the sky a milky shade (while making sunsets a deep, blood red), we will alter not just Earth, but also ourselves, our understanding of how we fit within the natural environment. This is itself a dicey experiment. If we were to make the clouds glossy and the sky white, dot the horizon with dirigibles in a kind of Blade Runner set piece, what would be the impact on the collective human psyche?

We may be technologically capable of hacking the sky, but politically and ethically unprepared to do so. After all, it's been more than 20 years since the public learned that there were "human fingerprints" on the global climate. And as the impasse over emissions reductions proves, we still haven't come to terms with the moral implications of that fact. Are we ready, then, to go a step further and put our hand on a lever controlling the weather?

The idea of dimming the sun carries a number of problems. First, take the ethical conundrum of unequal benefits. What if world leaders decided to deploy the sulfur option and, as one climate model has suggested, an engineered cooling led to a decrease in monsoon rains over Asia? In such a scenario, geo-engineering could benefit some 5 billion people, while putting another 2 billion people in danger of drought and famine.

The risk of unequal benefits connects to a second difficult question: Who would control such powerful technology? Few people would want the US (or Chinese) military to run the weather. Corporate control would have its own drawbacks. As Robock put it to me: "Would you trust the ExxonMobil geo-engineering unit?" Leaving management of a makeshift sky to the lowest bidder seems imprudent, to say the least.

Thernstrom says one of the virtues of geo-engineering is precisely this centralized control. While unilateral emissions reductions are pointless, unilateral geo-engineering could work. Any industrial power could likely do it on its own -- which means you don't need collective action to cool the planet; you just need countries not to object.

But even if the major powers agreed to cool the globe, reaching consensus on how exactly wouldn't be simple. "How do we even decide what the temperature of the planet will be?" Robock wonders. "Whose hand will be on the thermostat? What if Russia and Canada decide they want it warmer and India wants it cooler? How do you decide those things?"

Imagine that the United Nations took control of the planetary thermostat. That would prevent any country from having a monopoly over geo-engineering or, worse, having several countries deploy geo-engineering at cross-purposes. But UN oversight would still involve geo-politics. It's been close to impossible to get the major polluters to agree to emissions reductions. Finding cooperation on something as powerful as geo-engineering would be at least as complicated.

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