Ernest Agyemang-Oko , Hu Yang , Xiaoxu Shi, Gerrit Lohmann

The potential climate impact of solar geoengineering is examined using climate model simulations by artificially reducing the incoming solar radiation at the top of the atmosphere. Climate scenario simulations indicate that a doubling of atmospheric carbon dioxide (2xCO2) induces a surface temperature rise which is amplified over the poles primarily during the respective winter. The warming also causes intensification and poleward shift of the global precipitation pattern. In our model, a 2.1% globally uniform solar reduction can largely compensate the global mean warming caused by a doubling of CO2. We find that solar shading is efficient to restore the temperature at the region where the background sunshine is strong, regionally at low-latitudes, seasonally during summer. Solar shading would lead to an overall weakening of the global hydrological cycle, resulting in a large-scale drought. A 3.6% solar reduction in the tropics can largely reduce the tropical and global warming as well. However, it reduces the precipitation at the central tropics, while increase the precipitation over the monsoon region. Comparatively, a 14% solar reduction over the poles can effectively prevent the polar summer temperature increase and sea-ice retreat. However, caused by the increased temperature gradient, polar solar shading increases the storm activity at high-latitudes, especially during summer when the solar reduction reaches its maximum amplitude. Our simulations show that solar shading could be an effective way to stabilize the polar cryosphere. Nevertheless, it has a strong impact on the hydrological cycle and provides a heterogenous regional climate signal.