Substantial climate response outside the target area in an idealized
experiment of regional radiation management
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, RRM) 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 of cirrus (terrestrial radiation
management, TRM). The region chosen is North America, and we simulate a
period of 30 years. The implemented sustained RM resulted in a net local
radiative forcing of -9.8 Wm and a local cooling of -0.8 K. Surface
temperature (SAT) extremes (90 and 10 percentile) show negative
anomalies in the target region. However, substantial climate impacts are
also simulated outside the target area, with warming in the Arctic 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 intermittent RRM
results in most cases in a successful reduction of temperatures locally,
with substantially smaller impacts outside the target area, compared to
the sustained RRM.