Regional Scale Analysis of Climate Extremes in an SRM Geoengineering Simulation, Part 2:Temperature Extremes

In this study, we examine the statistics of temperature extremes in a model simulation of solar radiation management (SRM) geoengineering. We consider both intensity and frequency-based extreme indices for temperature. The analysis is performed over both large-scale domains as well as regional scales (22 Giorgi land regions). We find that temperature extremes are substantially reduced in geoengineering simulation: the magnitude of change is much smaller than that occur in a simulation with elevated atmospheric CO₂ alone. Large increase (~10–20 K) in the lower tails (0.1 percentile) of T_min and T_max in the northern hemisphere extra-tropics that are simulated under doubling of CO₂ are reduced in geoengineering simulation, but significant increase (~4–7 K) persist over high-latitude land regions. Frequency of temperature extremes is largely offset over land regions in geoengineered climate. We infer that SRM schemes are likely to reduce temperature extremes and the associated impacts on a global scale. However, we note that a comprehensive assessment of moral, social, ethical, legal, technological, economic, political and governance issues is required for using SRM methods to counter the impacts of climate change.