Last month I wrote about geoengineering, controversial schemes to deliberately manipulate the Earth’s climate to slow the planet’s warming. I focused mostly on a proposal often called “solar radiation management” (PDF), in which sunlight is blocked in the upper atmosphere in order to reduce warming at the planet’s surface. A new study, cowritten by one of the main sources in my piece, Stanford’s Ken Caldeira, makes a major conclusion about this type of geoengineering: It may cool the planet, but it won’t prevent dangerously high levels of carbon dioxide from wreaking havoc on our oceans.
As MoJo’s environmental correspondent Julia Whitty has written, our oceans are already at their breaking point: Man-made emissions have negatively impacted the ocean's chemistry, and toxic waste is being dumped into our oceans without regard for its harmful impact on fragile marine ecosystems. To make matters worse, scientists fear that large-scale geoengineering proposals could cause further acidification of our oceans (for instance, the sulfur injected into the atmosphere in a solar radiation management scheme would fall back to the Earth's surface through precipitation), damaging the lifeforms that live there. More recent geoengineering studies (PDF), however, allayed those fears, finding that solar radiation management wouldn’t acidify the oceans as much as first anticipated.
Nonetheless, the Caldeira report finds that our oceans and coral life are in grave danger—and even the best-case-scenario geoengineering scheme to block out the sun’s rays won’t help the oceans much. Paired with a report from earlier this year stating that global warming is essentially irreversible, that CO2 will hang around in the atmosphere for around a thousand years or so, the Caldeira paper suggests that solar radiation-related geoengineering efforts aren't worth pursuing.
Perhaps geoengineering researchers would be better off focusing on ways to remove CO2 from the atmosphere, like synthetic trees that “scrub” the CO2 out of the air. After all, why waste time, money, and manpower on a geoengineering scheme like solar radiation management if, as this latest research suggests, it won’t do much to save our planet?