Rx for a carbon-warmed planet: Sulfuric acid?

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Spraying the stratosphere with sulfuric acid to cool the planet? It’s not as nuts as it sounds, according to David Keith, CEO of Carbon Engineering.

Carbon Engineering CEO David Keith at EMtech 2012

“If the problem is that we’re warming up, an obvious stupid solution is to make some shade. [For that] you would need 1 percent shade to compensate for the CO2 we’ve added. That’s 5 trillion meters of solid material. It sounds crazy and expensive. Well, it may be crazy but it’s not expensive or that hard,” Keith told attendees at EMtech 2012 at MIT on Wednesday. 

One possible solution is to use a sub-micron sea salt spray to create a marine cloud to deflect sunlight. But Keith is working on the sulfuric acid solution where planes would “seed” the stratosphere with droplets that deflect sunlight. “There are lots of bad things about this but also some pretty good things,” said Keith, who is also a professor of applied physics at Harvard. Founded in 2009 in, Calgary, Alberta Carbon Engineering has attracted investors including Microsoft co-founder Bill Gates.

Keith posited that the project could start with three “re-engined” Gulfstream jets in 2020 delivering their payloads — with that number growing to 10 aircraft carrying a quarter million tons of sulfur per year at a cost of $700 million.

Keith readily acknowledged the downside. Sulfuric acid, after all, is a highly corrosive material. “You can’t do this forever but that’s not to say it’s not worth doing for the short term,” he said.

In reality, some 50 million tons of sulfur are already pouring into the lower atmosphere now — much of it from coal. This kills 50 million people a year, and 20,000 in the U.S., he said.

Keith would probably be the first to say that this is an imperfect solution to an intractable problem. But, because of the political impossibility of putting a price on carbon emissions, the world will have to consider worst-case scenarios.  “The question then is what if we have to geo-engineer the planet to offset the damage we’ve done?” he said. Sulfuric acid spray is one way to do that.

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