A Nobel Laureate has proposed a possible but extremely unpalatable method to reduce global warming. The basic idea is to inject sulfate pollutants into the stratosphere, which will have a net effect of cooling the Earth. There is good experimental and observational support for the validity of this idea. When Mount Pinatubo erupted, it injected a large mass of sulfates into the stratosphere, causing the globally averaged surface temperature to drop by half a degree for a year. Other eruptions in history, plus a fair amount of climate modelling research, also support this idea. Given that the amount of global warming over the last 100 years has been estimated as 0.6 degrees, combined with the reputation of the scientist proposing it, this dramatic cooling mechanism is receiving some serious attention.
His method reminds me of 1940’s classic Science Fiction. I quote from CNN,
The Dutch climatologist, awarded a 1995 Nobel in chemistry for his work uncovering the threat to Earth’s atmospheric ozone layer, suggested that balloons bearing heavy guns be used to carry sulfates high aloft and fire them into the stratosphere.
The Nobel Prize-winning scientist who first made the proposal is himself “not enthusiastic about it.”
“It was meant to startle the policymakers,” said Paul J. Crutzen, of Germany’s Max Planck Institute for Chemistry. “If they don’t take action much more strongly than they have in the past, then in the end we have to do experiments like this.”
Known side effects would include increased acid rain globally (we are talking about sulfur dioxide, after all). There might also be a tendency for developing and/or irresponsible parties to delay reductions of greenhouse gases, given this method of ameliorating the problem.
This is an idea that could work without the monumental effort usually associated with global climate change scenarios. In the very short term, some might argue that here is a “viable” use for sulfur emissions. The most disturbing aspect of this idea is that it would be physically doable by the First World Countries, and it might be politically viable and also attractive for major industrial interests. Also, we don’t need to inject as much as Pinatubo; the rate of injection would only be enough to slow down or balance the posited global warming rate.
Engineering the global climate makes me think of the “good old days” of the 1950s and 60s, when we tried to interfere in local ecologies by adding species to new environments, and with the expectation that the ecologies would react in a linear and predictable manner (…hollow laugh…). This happened in Australia with rabbits, in Newfoundland with shrews and moose (we started with six, and a hundred years later we have about 120-140,000 healthy but somewhat inbred specimens). It’s hard enough trying to predict physical and chemical feedbacks in the climate; effects on ecologies, and possible feedbacks to local and global climates, make me want to go somewhere else.
As an aside, human effects on climate are not restricted to the Industrial Revolution. Consider the following three examples. First there is the obvious short-term interaction between farmers and the Sahel region of northern Africa. Second is the deleterious change over the centuries in the climate of the Fertile Crescent, most of which was man-made and was related to agricultural methods. Third is one that surprised me when I first read of it, but which does make sense. When agrarian societies started migrating into Western Europe, it was basically a series of vast forests. They started cutting down the trees and planting grains and grasses. Continue for 500-1000 years, and most of the sub-continent became grasslands and farms.
Think about it. Millions of square kilometres of forest became millions of square kilometres of fields and grasslands. The albedo of the ground changes, the rate of evapotranspiration (transfer of water vapour into and out of the ground and the plant life) changes, the rate at which the ground cools and is heated changes massively. Voila! The climate of all of Europe and areas downwind to the east are modified by primitive man, without resort to pollution nor greenhouse gases, and the ecologies had to adapt. No more Aurochs, Big Bad Wolves, getting lost in the forest for days, etc. The Black Death in the 1340’s slowed this change for a couple of generations, but didn’t stop it.
Finally, this sulfur injection proposal actually be the most viable solution, given the lack of progress and resistance on other fronts. We have a positive talent for changing the world around us in unpredictable ways without even noticing it; we used to blame it on Evil Chance, the much maligned Nature, or other gods. Now we’re getting into the hubris business big-time. Let’s hold our breaths and see what happens.
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