By M. Granger Morgan, Robert R. Nordhaus, and Paul Gottlieb
As this approach to geoengineering gains attention, a coordinated plan for research will make it possible to understand how it might work and what dangers it could present.
Emissions of carbon dioxide (CO2) and other greenhouse gases (GHGs) continue to rise. The effects of climate change are becoming ever more apparent. Yet prospects for reducing global emissions of CO2 by an order of magnitude, as would be needed to reduce threats of climate change, seem more remote than ever.
When emissions of air pollutants, such as sulfur dioxide and oxides fo nitrogen, are reduced, improvements occur in a matter of days or weeks, because the gases quickly disappear from the atmosphere. This is not true for GHGs. Once emitted, they remain in the atmosphere for many decades or centuries. As a result, to stabilize atmospheric concentrations, emissions must be dramatically reduced. Further there is inertia in the earth-ocean system, so the full effects of the emissions that have already occurred have yet to be felt. If the planet is to avoid serious climate change and its largely adverse consequences, global emissions of GHGs will have to fall by 80 to 90% over the next few decades.
Becausee the world has already lost so much time, and because it does not appear that serious efforts will be mae to reduce emissions in the major economies any time soon, interest has been growing the possibility that warming might offset by engineering the planet: a concept called geoengineering. The term solar radiation management (SRM) is used to refer to a number of strategies that might be used to increase the fraction of sunlight reflected back into space by just a couple of percentage points in order to offset the temperature increase caused by rising atmospheric concentrations of CO2 and other GHGs. Of these strategies, the one that appears to be most affordable and most capable of being quickly implemented involves injecting small reflective particles into the stratosphere.
There is nothing theoretical about whether SRM could cool the planet. Every time a large volcano explodes and injects tons of material into the stratosphere, Earth's average termperature drops. When Mount Pinatubo exploded in 1991, the result was a global-scale cooling that averaged about half a degree centigrade for more than a year.
So SRM could work. As undesirable impacts from climate changes mount up, the temptation to engage in SRM will grow. But what if someone tries to do it before we knew if it will work, or what dangers might come with it? The time has come for serious research that can get the world answers before it is too late. To that end, we offer a plan.
The above is an excerpt from an article that was originally published in the Spring 2013 issue of Issues in Science and Technology. Read the full article here.