There is growing awareness that the consequences of global warming are happening now and are no longer only warnings about future changes, and that action to limit inputs of GHGs to the atmosphere are inadequate to prevent large and dangerous changes in the climate system. Climate intervention is a set of proposed activities designed to intentionally change global climate to reduce anthropogenic global warming. Solar radiation management (SRM) is one approach to climate intervention. It aims to reduce the temperature of the Earth-atmosphere system by reducing solar radiation reaching Earth’s surface. It includes known risks and poorly understood and novel risks. While a great deal of work has been done on climate projections for SRM, almost nothing is known about its predicted ecological impacts. Climate scientists have not focused on the impacts of SRM to natural living systems, and most ecologists have not been fully aware of the extensive work on SRM. We address the key ecological uncertainties associated with SRM and ask, How do proposed SRM scenarios affect regional to global ecological systems? We consider changes resulting from SRM on fire frequency and intensity, and climate-vegetation feedbacks to these effects. Which systems would be most at risk from SRM and where would it effectively ameliorate anthropogenic climate change? We also ask if SRM should be designed for a different target than temperature reduction, e.g., minimizing impacts on biodiversity hotspots. Using SRM projections from GeoMIP and the overshoot scenario and RCP 4.5 and 8.5, we investigate effects of SDM for plants and biome distributions to begin to address these questions.
Results/Conclusions
We discuss a suite of direct impacts and unintended side-effects, both known risks and potential risks; outlining how the mean, spatial variability and temporal variability of key climate factors can be altered by SRM. We propose examples of spatially explicit impacts of SRM on ecological systems including shifting distributions of terrestrial organisms, biodiversity and biomes in direct response to the changes predicted for climatic factors. We emphasize the importance of ecological impacts of indirect effects of SRM on water balance, disturbance frequency and intensity, changes to UV and direct/indirect visible light ratios. Marine physical factors affected may include changes in radiation profiles, ocean acidification, water temperature, salinity, and biogeochemical perturbations, with impacts on circulation, dispersal, biotic realms, and increase in the duration and extent of sea ice.