Modern humans have, up until this point, done a pretty horrible job of cutting down on the amount of greenhouse gases that are released into the atmopshere to stave off climate change. As we inch ever closer to the tipping point where reducing emissions won't make a difference, some scientists are suggesting that we try to "geoengineer" the planet to counteract our emissions with everything from algae-lined buildings and forests of synthetic trees to ships that spray climate-altering clouds into the sky. These are ideas fit for a big-budget Hollywood movie (and they may even work). But one new study (PDF) says that regardless of whether geoengineering works, we can't afford it.
The study, appropriately titled "The economics (or lack thereof) of aerosol geoengineering," finds that aerosol engineering (the practice of shooting aerosol particles into the atmosphere to cool down the planet, one of the more common geoengineering suggestions) isn't close to economically viable. But when it comes to the end of the planet, what's a few billion dollars?
The problem is that aerosol geoengineering only works as long as the aerosol particles are still in the air—and continuing to spray particles for decades on end will cost an unthinkable amount of cash. The report explains:
Aerosol geoengineering hinges on counterbalancing the forcing effects of greenhouse gas emissions (which decay over centuries) with the forcing effects of aerosol emissions (which decay within years). Aerosol geoengineering can hence lead to abrupt climate change if the aerosol forcing is not sustained. The possibility of an intermittent aerosol geoengineering forcing as well as negative impacts of the aerosol forcing itself may cause economic damages that far exceed the benefits.
So when the aerosol particles cease to linger in the air, Earth could experience "abrupt warming with rates that are unprecedented for modern human societies and would likely cause sizeable economic damages." And knowing humanity, there is a decent chance that geoengineering techniques will work only intermittently because of cash shortages, wars, and everything else that causes us to be an unreliable species.
The concerns about aerosol geoengineering apply to many other techniques as well. A recent proposal to pump tiny bubbles into the ocean to lower temperatures and increase reflectivity would also probably cause abrupt climate change if the bubbles ceased to exist; the same could be said for the Copenhagen Consensus Center's vision of using ships to gather sea water and spray it out of tall funnels to create clouds.
Cutting CO2 emissions the old-fashioned way may not work, but least we will be more prepared for climate change if it happens relatively slowly than if we all of a sudden find ourselves on an uninhabitable planet. We would rather take our chances with prolonged misery.
[Photo by hekris]