Peak shaving with solar radiation modification 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 modification (SRM) is the idea to cool the planet by increasing the reflection of incoming solar radiation. SRM 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 SRM 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 approximately 5% for multi-decade overshoots up to approximately 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. Thus, SRM, when deployed as a complement to emissions reductions and CDR, could end overshoot decades earlier than otherwise.