Sulfate aerosols, commonly released by volcanoes, serve to scatter incoming solar energy in the stratosphere, preventing it from reaching the surface. To investigate the feasibility of deliberately mimicking the effect of volcanic aerosols, Rasch et al. explore scenarios in which aerosol properties are varied to assess interactions with the climate system. Through model simulations, they discover that, because stratosphere-troposphere exchange processes change with increasing levels of aerosols, about 50 percent more aerosols would have to be injected into the atmosphere than in the scenario where such processes stayed constant. Further, almost double the level of aerosol loading is required to counteract greenhouse warming if aerosol particles are as large as those seen during volcanic eruptions. The authors caution that geoengineering methods to mask global warming may have serious environmental consequences that must be explored before any action is taken.-American Geophysical Union
