Regional radiation management: Climate response outside the target area, an idealized study

Abstract: Radiation management (RM) has been proposed as a conceivable climate engineering (CE) intervention to mitigate global warming. In this study, we use a coupled climate model (MPI-ESM) with a very idealized setup to investigate the efficacy and risks of CE at a local scale in space and time (regional radiation management, RRE) assuming that cloud modification is technically possible. RM is implemented in the climate model by the brightening of low-level clouds (solar radiation management, SRM) and thinning or dissipation of cirrus (terrestrial radiation management, TRM) over North America over a period of 30 years. The implemented sustained RM resulted in a net local radiative forcing of -9.8Wm -2 and a local cooling of -0.8 K. Surface temperature (SAT) extremes (90th and 10th percentile) show negative anomalies in the experimental region. However, substantial climate impacts are also simulated outside the target area, with an Arctic warming and pronounced precipitation change in the eastern Pacific. As a variant of RRM, a targeted intervention to suppress heat waves (HW) is investigated in further simulations by implementing intermittent cloud modification locally, prior to the simulated HW situations. The RRM results in a partial local HW suppression with substantially smaller impacts outside the target area compared to the sustained RRM.