Scientists at Harvard University have discovered yet another unexpected — not to mention unintended — consequence of climate change. Thunderstorms on steroids — supercharged by the increased heat energy trapped in the atmosphere — are, as it were, punching massive holes in the ozone layer. The implications for life on earth are profound, and profoundly negative.
The scientists, under the leadership of professor of atmospheric chemistry James G. Anderson, were not even looking at the ozone layer. “We were investigating the behavior of convective water vapor as part of our climate research,” Anderson told Harvard Magazine, “not ozone photochemistry. What proved surprising was the remarkable altitude to which water vapor was being lofted—altitudes exceeding 60,000 feet—and how frequently it was happening.” This was thought to be impossible. (“Anvil head” is the common name given a thunderstorm whose top is sheared flat and spread out, so that it resembles an anvil, by encountering the stratosphere about 30,000 feet up.)
The Harvard team immediately recognized that they had stumbled upon much more than a curiosity. The presence of water vapor at these altitudes initiates the complex chemistry of high-altitude ozone destruction, a process previously thought to occur only over the extremely cold polar regions.
It appears that each of these superstorms affects the ozone chemistry in a large area for a week; that the effects include an increase in the rate of destruction of ozone by a hundredfold, exceeding regeneration rates by two orders of magnitude. And the thunderstorms are not only getting bigger, they are coming more often.
To review: ozone in the stratosphere shields the earth below it from the more harmful, ultraviolet wavelengths of solar radiation. If the ozone layer is weakened, living things below suffer increased rates of skin cancer, eye damage and destruction of DNA. When we learned in the 1970s that chlorine in some of our most useful products — refrigerants and aerosols — was making it to the stratosphere and acting as a catalyst in breaking down ozone and tearing holes in the layer, we banned the products. It is one of the world’s few examples of an effective response to an environmental problem.
It is not likely that we would act so responsibly today. Republican candidates for president would swear on Bibles that they do not believe in the ozone layer, and that would be that. But in any case, no such neat and discrete response to this problem as banning a single set of products is possible.
In this case, the primary cause is not chlorine (although residual amounts left in the atmosphere by our overuse of it figure in the chemistry) but global warming itself. And those who study the effects of the greenhouse pollutants tell us that the harm we have already done will take a thousand years to play out.