Quantifying the effects of solar geoengineering on vegetation

Climate change will have significant impacts on vegetation and biodiversity. Solar geoengineering has potential to reduce the climate effects of greenhouse gas emissions through albedo modification, yet more research is needed to better understand how these techniques might impact terrestrial ecosystems. Here, we utilize the fully coupled version of the Community Earth System Model to run transient solar geoengineering simulations designed to stabilize radiative forcing starting mid-century, relative to the Representative Concentration Pathway 6 (RCP6) scenario. Using results from 100-year simulations, we analyze model output through the lens of ecosystem-relevant metrics. We find that solar geoengineering improves the conservation outlook under climate change, but there are still potential impacts on terrestrial vegetation. We show that rates of warming and the climate velocity of temperature are minimized globally under solar geoengineering by the end of the century, while trends persist over land in the Northern Hemisphere. Moisture is an additional constraint on vegetation, and in the tropics the climate velocity of precipitation dominates over that of temperature. Shifts in the amplitude of temperature and precipitation seasonal cycles have implications for vegetation phenology. Different metrics for vegetation productivity also show decreases under solar geoengineering relative to RCP6, but could be related to the model parameterization of nutrient cycling. The coupling of water and carbon cycles is found to be an important mechanism for understanding changes in ecosystems under solar geoengineering.