Peak Shaving with Solar Radiation Management Would Shorten Global
Temperature Overshoot
Abstract
Projected rates of emissions reductions are unlikely to keep global
temperatures from crossing the Paris Agreement temperature targets.
Large-scale carbon dioxide removal (CDR) could help recover a target
temperature after it has been exceeded, producing an overshoot scenario.
Solar radiation management (SRM) is the proposal to cool the planet by
increasing the reflection of incoming solar radiation. It could be used
in an overshoot scenario for peak shaving, where SRM is deployed to
maintain a temperature target during the overshoot. Here, we quantify
the effect of peak shaving on the duration of the overshoot using an
adapted extension of the SSP2-4.5 scenario and an ensemble of variants
of the FaIR simple climate model. We find a substantial reduction in
overshoot duration, which ranges from ∼5% for decadal overshoots up to
∼20% for multi-century overshoots. The shortening is predominantly
driven by the ocean response to peak shaving. Peak shaving results in
lower ocean temperatures relative to the overshoot scenario, inducing a
stronger surface temperature response to decreasing and negative
emissions, driving overshoot shortening. Our results also indicate that
peak shaving with SRM would reduce the cumulative net negative emissions
needed to end temperature overshoot by ∼27%. Thus, SRM, when deployed
as a complement to emissions reductions and CDR, could end overshoot
decades earlier than otherwise and at a substantially lower cost.