Optimizing climate change reduction

Scientists at the Carnegie Institution's Department of Global Ecology have taken a new approach on examining a proposal to fix the warming planet.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. The Carnegie researchers started out differently by asking how, if people decided what kind of climate they want, they would go about determining the aerosol distribution pattern that would come closest to achieving their climate goals. This new approach is the first attempt to determine the optimal way of achieving defined climate goals.
The Carnegie scientists ran five simulations using a global climate model with different sulfate aerosol concentrations depending on latitude. They then used the results from these simulations in an optimization model to determine what distribution of sulfates would come closest to achieving specified climate goals. They then tested these distributions in the global climate model to assess how well the climate goals were met.
They found that with more sulfate over the poles than in tropical regions, the temperature distribution was more like that of a low carbon dioxide climate. However, changes in the water cycle were most effectively diminished when the sulfates were distributed nearly uniformly.
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.