In Part II of “What You Always Wanted to Know About Geoengineering but Were Afraid to Ask,” we discussed a type of solar radiation management that involves pumping a lot of sulfur dioxide into the stratosphere. As you might recall, the plan was inspired by a volcanic eruption, in 1991, that spewed sulfur into the stratosphere and lowered average temperatures in the Northern Hemisphere by a few degrees for a couple of years. The blog ended by asking: Might the Earth’s temperature drop too much if some volcanoes suddenly belched a lot of sulfur into the stratosphere on top of the sulfur that we pumped out there, and, if so, what could we do about it?
(Well, now that we’re back up to speed, let’s get on with Part III.)
While the probability of several, sulfur-spewing volcanoes erupting all at once isn’t very high, Professor of Geophysical and Climate Hazards Bill McGuire argues that global warming is causing the probability to go up. (How? Why? What? . . . Huh???) Here’s how he explains it: “The world we inhabit has an outer rind that is extraordinarily sensitive to change. While the Earth’s crust may seem safe and secure, the geological calamities that happen with alarming regularity confirm that this is not the case.” We should think of “the Earth beneath our feet,” he writes, “as a slumbering giant that tosses and turns periodically in response to various pokes and prods” and be aware that environmental changes atop the Earth’s crust could arouse the sleeping giant. McGuire notes that following the last ice age, “as the immense ice sheets melted and colossal volumes of water were decanted back into the oceans, the pressures acting on the solid Earth also underwent massive change. In response, the crust bounced and bent, rocking our planet with a resurgence in volcanic activity, a proliferation of seismic shocks and burgeoning giant landslides.”
Now, with glaciers around the world “melting at a staggering rate,” Alaska’s permafrost thawing, sea levels rising, and the Earth’s surface beneath massive ice sheets “rebounding in response to rapid melting,” McGuire wonders if “our planet’s crust will begin to toss and turn once again.” If it does, it could “squeeze magma out of susceptible volcanoes.”
Will global warming cause more volcanic activity, more landslides, avalanches, earthquakes, and tsunamis? No one can say for certain; nevertheless, for McGuire, the bottom line is clear: “[T]hrough our climate-changing activities we are loading the dice in favour of escalating geological havoc.” So, before we start injecting sulfur into the stratosphere, we had better come up with a plan for what to do in case a combination of natural eruptions and artificial injections causes too much sulfur to block too much sunlight. Should we task the Pentagon to come up with plans to deploy an army of robo-maids with vacuum cleaners to suck up all the stratospheric sulfur? (Good idea? Maybe not.)
As we’ve seen, there are a number of reasons to think that spraying sulfur into the stratosphere is a bad idea. The fundamental fly in the sulfur-aerosol ointment, however, is that it merely treats a symptom, warming, instead of the cause, greenhouse-gas emissions. As a matter of fact, all of the solar-radiation-management methods—including white roofs, outer space mirrors, a Saturn-like ring around the Earth, Styrofoam icebergs and some other ideas that I haven’t bothered to mention—only address global warming. Meanwhile, greenhouse-gas emissions are brewing a sea of troubles in the ocean. (Pun and cliché intended. Sorry.) We’ll discuss those troubles in the next installment of “What You Always Wanted to Know About Geoengineering but Were Afraid to Ask.”
Thank you for reading this post. If you have time, please come back to this blog for the next one.
 McGuire, Bill. “Climate Change Will Shake the Earth.” Guardian. February 26, 2012. http://www.guardian.co.uk/environment/2012/feb/26/why-climate-change-shake-earth