When you drive down the wrong road and get lost, is it wiser to backtrack and start fresh or just keep roaring blindly ahead, hoping you’ll find your way before it’s too late? Battling global warming with geoengineering schemes seems a lot like the latter option, since we are already 150 years down the fossil fuel-burning road and lost in the resulting gigantic and (until recently) unintentional climate experiment.
I mention this because geoengineering has been popping up a lot lately in the media. Today there’s another scientific study out which models and evaluates some schemes for battling global warming by trying to reduce the amount of sunlight reaching the Earth’s surface, what’s called Solar Radiation Management, or SRM.
“We compared the climate impact of three different SRM techniques: Injection of sulfate into the stratosphere, mirrors in space, and artificial emissions of sea salt over the oceans,” write authors Niermeier, Schmidt, Alterskjær and Kristjánsson in their paper in today’s issue of the Journal of Geophysical Research-Atmospheres. Using global climate simulations, the researchers compared the cooling techniques to each other and to a simulation where the greenhouse gases were fixed at estimated concentrations from the year 2020 until the rest of the century. “We mainly compared the differences between the engineered climates around 2065 and the reference climate of 2020.”
The results suggest that reducing the amount of sunlight by any of these techniques enough to balance the greenhouse heating could have the side effect of inordinately lowering precipitation. So we could potentially trade heating for drying. And, of course, there is still the dangerous acidification of the oceans, which SRM does nothing to address.
The researchers also give a warning about their work: “Both the actual greenhouse gas forcing and the forcing of a certain amount of SRM can be estimated much more accurately in the model than in reality. Natural climate variability would pose a challenge for the rapid detection of SRM effects. It should also be mentioned that a potential abrupt ending of SRM would cause rapid climate change.”
In fact, they cite previous research which calculated that for the decade after halting SRM, the global mean climate could suffer a warming jolt of 2.4 degrees Celsius per decade. Ouch! Sounds like a bad case of SRM detox.
Finally, they point out that SRM isn’t necessarily free of political, legal and technical issues, the same issues that bog down progress in reducing greenhouse gas emissions. All of which brings me back to my original thought, that perhaps we’d be better off concentrating on reversing the geoengineering project we have already started, rather than piling on another set of problems and uncertainties. Perhaps the only sensible geoengineering is the kind that focuses on reducing greenhouse gases. After all, sunshine is not the cause of global warming; greenhouse gases are.
Image: An exaggerated illustration of a space lens. (Mikael Häggström Wikimedia Commons)