Consistent weakening of the extratropical storm tracks in an idealized solar geoengineering scenario

Solar geoengineering through reduction of planetary albedo could maintain global mean surface temperature at preindustrial levels and avoid many known risks of climate change, but such an intervention would nonetheless alter the structure of atmospheric temperature and humidity. Changes in moisture content, static stability, and meridional temperature gradients could all affect the mean available potential energy (MAPE) of the atmosphere and thus influence the extratropical storm tracks. Here, we analyze climate model results from experiment G1 of the Geoengineering Model Intercomparison Project (GeoMIP), in which an instantaneous quadrupling of CO­₂ relative to pre-industrial levels is balanced by a reduction in incoming solar radiation. We demonstrate a consistent weakening of the northern and southern extratropical storm tracks in this idealized solar geoengineering scenario. By contrast, in the absence of geoengineering the southern storm track strengthens in response to the increase in CO₂. We connect these changes in storm track intensity to the changes in mean temperature and humidity using MAPE, and its convective and non-convective components. Our results highlight the potential for geoengineering interventions to induce novel climate changes, with possible impacts on weather extremes, ocean circulation, the carbon cycle, and atmospheric transport of energy, water and momentum.