Palo Alto, CA — Scientists at the Carnegie Institution’s Department of Global Ecology have taken a new approach on examining a proposal to fix the warming planet. So-called geoengineering ideas—large-scale projects to change the Earth’s climate—have included erecting giant mirrors in space to reflect solar radiation, injecting aerosols of sulfate into the stratosphere making a global sunshade, and much more. Past modeling of the sulfate idea looked at how the stratospheric aerosols might affect Earth’s climate and chemistry.
About the image: Climate model results relative to the low-CO2 climate. The left side shows results when temperature differences are minimized. The right side shows results when precipitation minus evaporation (PminusE) is minimized. The upper panel shows results for temperature and the bottom panel shows results for precipitation minus evaporation. In the model, geoengineering reduces the amount of change in both temperature and precipitation minus evaporation caused by high CO2 concentrations. Using a parabolic distribution of aerosols (more aerosols in the polar regions) slightly improves the cancellation of temperature changes but slightly degrades the ability to reverse changes in precipitation minus evaporation. Image credit: Carnegie Institution for Science
They found that if the right amount of uniformly distributed aerosols were put into the stratosphere, the magnitude of the temperature change could be diminished by 90% and the change in runoff by two-thirds. Under another scenario with aerosol distributions varying latitudinally as a parabola, the magnitude of temperature change was reduced by 94%, but then runoff changes were only reduced in half.
“Changes in temperature and the hydrological cycle cannot be simultaneously minimized because the hydrological cycle is more sensitive to changes in solar radiation than are surface air temperatures,” explained Ban-Weiss.
“It’s important to stress that geoengineering options can never reverse all of the consequences of greenhouse gas emissions. For example, it doesn’t reverse ocean acidification. And it obviously has associated risk. So geoengineering is not an alternative to greenhouse gas emissions reductions.” said Ban-Weiss.
*Source: Carnegie Institution for Science