As the emissions of carbon dioxide have continued largely unabated over the past decade, a number of people have given thought to geoengineering, or changing the environment in a way that tweaks the planet’s thermostat. Although people have suggested some exotic interventions—reflecting sunlight away from the Earth with orbiting mirrors—more serious consideration is being given to pumping sulfur dioxide into the stratosphere. But a new paper in Nature Climate Change suggests that focus might be keeping us from considering even better options.
Sulfur is a major focus in part because we know it will work, since major volcanic eruptions provide a natural test of it. The sulfur released in eruptions can reach the stratosphere, where it combines with water to produce aerosol particles that reflect sunlight back to space. It’s estimated that the aerosols created in the wake of the eruption of Mount Pinatubo were large enough to drop the global temperature by half a Kelvin for two years.
Sulfur is also abundant and cheap, making the raw materials for this form of geoengineering relatively inexpensive. In fact, the whole process is expected to be so cheap that some have estimated that it might be within reach of a handful of wealthy individuals. But, even if you were committed to reflecting sunlight back to space, there are some downsides to using sulfur. The sulfur would have to be constantly replenished, and its constant presence at high altitude would trigger chemical reactions that could damage the ozone layer.
from Ars Technica