Climate Model-Based Assessments of Regional Responses to Solar Geoengineering

The most straightforward way to avoid the potentially dangerous climate change is to reduce, and eventually eliminate, carbon dioxide emissions from the combustion of fossil fuels. However, given the slow progress on this front, a growing number of proposals have been made for deliberate intervention in the climate through “geoengineering”. Several methods have been proposed for deliberately tinkering with the Earth’s energy balance to counteract the warming effects of carbon dioxide and other greenhouse gases (GHGs): reflecting an increased fraction of sunlight back into space before it is absorbed by the Earth’s surface, increasing the transparency of the Earth’s atmosphere to outgoing longwave radiation, or even pumping water from the deep ocean to the surface ocean to cool surface air temperatures. All these proposals imperfectly compensate for the effects of GHGs, altering the intensity of the global hydrological cycle and resulting in shifting regional climate states even when global temperatures are held steady. Here I explore these tradeoffs, as simulated in earth system models.