Climate Impacts from Explosive Volcanic Eruptions, Solar Radiation Change, and CO2 Increase

Explosive volcanic eruptions can have substantial climate impacts. While the eruption magnitude is a key factor for the impact, limited studies have examined the influence from the unevenness of stratospheric aerosol loadings between the two hemispheres. In this study, we show that there are three major types of large volcanic eruptions in the 20th century according to the forcing structure: inter-hemispheric symmetric (Pinatubo-1991), asymmetrically Southern (Agung-1963) and Northern Hemispheric (Santa Maria-1902). Using the GFDL/FLOR coupled climate model, we conduct 30-member-ensemble 5-year simulations for each of the three eruptions. The two asymmetric eruptions, although with a weaker global forcing than the Pinatubo, can have a comparable surface temperature response in the eruption hemisphere, a stronger impact on precipitation that pushes the Inter Tropical Convergence Zone (ITCZ) away from the eruption hemisphere, and also a larger impact on tropical cyclones on the global scale. These impacts are also compared with that from solar radiation change and CO2 increase. Our findings demonstrate the importance of the volcanic spatial forcing structure in the climate impact.