资源环境科技发展态势分析平台

Solar geoengineering has been shown in modeling studies to successfully mitigate global mean surface temperature changes from greenhouse warming. Changes in land surface hydrology are complicated by the direct effect of carbon dioxide (CO2) on vegetation, which alters the flux of water from the land surface to the atmosphere. Here we investigate changes in boreal summer climate variability under solar geoengineering using multiple ensembles of model simulations. We find that spatially uniform solar geoengineering creates a strong meridional gradient in the Northern Hemisphere temperature response, with less consistent patterns in precipitation, evapotranspiration, and soil moisture. Using regional summertime temperature and precipitation results across 31-member ensembles, we show a decrease in the frequency of heat waves and consecutive dry days under solar geoengineering relative to a high-CO2 world. However in some regions solar geoengineering of this amount does not completely reduce summer heat extremes relative to present day climate. In western Russia and Siberia, an increase in heat waves is connected to a decrease in surface soil moisture that favors persistent high temperatures. Heat waves decrease in the central United States and the Sahel, while the hydrologic response increases terrestrial water storage. Regional changes in soil moisture exhibit trends over time as the model adjusts to solar geoengineering, particularly in Siberia and the Sahel, leading to robust shifts in climate variance. These results suggest potential benefits and complications of large-scale uniform climate intervention schemes.

Plain Language Summary Climate change is a difficult problem and will likely require a wide range of solutions. The use of intentional climate interventions, also called solar geoengineering, could help combat the worst effects of climate change. Solar geoengineering refers to techniques that decrease the amount of sunlight reaching the Earth's surface in order to cool the planet. While this method may be helpful in some ways, we also need to understand the risks or any unintended consequences. In this work we focus on the potential impacts of solar geoengineering on extreme heat events, such as heat waves. We use a climate model to study how the frequency of these events is affected by solar geoengineering and compare with how future climate change impacts extremes. Our results show that solar geoengineering produces fewer extreme heat events than the future with global warming. However, some places show an increase in extremes relative to the climate of today. Finally, we find that water stored in the soils is an important factor in determining the local response of extreme heat events to solar geoengineering.