Assessing Regional Climate Trends in West Africa Under Geoengineering: A Multi-model Comparison of UKESM1 and CESM2

Abstract

This study examines West Africa’s climate vulnerability under stratospheric aerosol injection (SAI) using two climate models: UKESM1 and CESM2. We analyzed temperature and precipitation patterns between 2050-2069 compared to 2015-2034 under two scenarios: SSP2-4.5 and ARISE-SAI-1.5. Our methodology involved evaluating temperature and precipitation anomalies, using Signal-to-Noise Ratio (SNR) analysis to assess climate signal reliability, and analyzing precipitation extremes through Cumulative Distribution Function (CDF) and Probability Density Function (PDF). Under SSP2-4.5, UKESM1 showed temperature increases of 1.8{degree sign}C while CESM2 showed increases of 1.0-1.2{degree sign}C. However, under ARISE-SAI-1.5, UKESM1 showed cooling (-0.3{degree sign}C below reference period) while CESM2 maintained slight warming (0-0.3{degree sign}C above reference). SNR analysis revealed that SAI significantly dampened the warming signal in UKESM1, making precipitation and temperature trends less detectable. CDF and PDF analyses showed that while SAI may reduce warming, it increases precipitation variability and uncertainty. These results emphasize the importance of multi-model comparisons when assessing geoengineering impacts, as models can produce varying results based on their sensitivity to radiative forcing and other factors.