Weakening of the extratropical storm tracks in solar geoengineering scenarios

©2020. American Geophysical Union. All Rights Reserved. Solar geoengineering that aims to offset global warming could nonetheless alter atmospheric temperature gradients and humidity and thus affect the extratropical storm tracks. Here, we first analyze climate model simulations from experiment G1 of the Geoengineering Model Intercomparison Project, in which a reduction in incoming solar radiation balances a quadrupling of CO2. The Northern Hemisphere extratropical storm track weakens by a comparable amount in G1 as it does for increased CO2 only. The Southern Hemisphere storm track also weakens in G1, in contrast to a strengthening and poleward shift for increased CO2. Using mean available potential energy, we show that the changes in zonal-mean temperature and humidity are sufficient to explain the different responses of storm-track intensity. We also demonstrate similar weakening in a more complex geoengineering scenario. Our results offer insight into how geoengineering affects storm tracks, highlighting the potential for geoengineering to induce novel climate changes.NASA (Grant NNX16AC98G)NSF (Grants 1122374, AGS 1552195 and AGS 1749986