29 Apr 2022
29 Apr 2022
Status: this preprint is currently under review for the journal ESD.

Deploying Solar Radiation Modification to limit warming under a current climate policy scenario results in a multi-century commitment

Susanne Baur1,2, Alexander Nauels2,3, and Carl-Friedrich Schleussner2,4 Susanne Baur et al.
  • 1CECI, Université de Toulouse, CERFACS, CNRS, Toulouse, 31100, France
  • 2Climate Analytics, Berlin, 10969, Germany
  • 3Australian-German Climate & Energy College, The University of Melbourne, Parkville, VIC 3010, Australia
  • 4Potsdam Institute for Climate Impact Research, D-14412 Potsdam, Germany

Abstract. A growing body of literature investigates the effects of Solar Radiation Modification (SRM) on global and regional climates. Previous studies have mainly focused on potentials and side-effects of SRM with little attention given to potential deployment timescales. Here, we look at a scenario that fails to achieve 1.5 °C-compatible mitigation and instead relies on SRM and Carbon Dioxide Removal (CDR) to avoid temperature rises above the threshold. Assuming SRM removes the incentive to increase mitigation beyond the currently pledged level of ambition, we assess SRM deployment lengths under three illustrative emission scenarios that follow current climate policy and are continued with varying assumptions about net-negative CDR (-11.5, -10 and -5 GtCO2yr-1). Under these assumptions, SRM would need to be deployed for around 245–315 years. We find only minor effects of SRM on the global net carbon flux decades after cessation. In total, around 976–1344 GtCO2 would need to be removed by CDR, much more than in so-called high-overshoot 1.5 °C scenarios. Our study points towards an additional risk of SRM that so far has received limited attention: Initialization and commitment to SRM would happen under the assumption that CDR can be scaled up sufficiently to allow SRM to be phased out again. In our scenarios, SRM would come with very long legacies of deployment, implying centennial commitments of costs, risks and negative side effects of SRM and CDR combined.

Susanne Baur et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esd-2022-17', Anonymous Referee #1, 11 May 2022
  • RC2: 'Review on esd-2022-17', Anonymous Referee #2, 24 May 2022
  • RC3: 'Comment on esd-2022-17', Anonymous Referee #3, 28 May 2022

Susanne Baur et al.

Susanne Baur et al.


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Short summary
Solar Radiation Modification (SRM) entails technologies that artificially cool the climate but do not act on the cause of climate change. We assess the time of commitment to SRM if it was implemented on top of a current policy scenario to keep warming to 1.5 °C until emission cuts and Carbon Dioxide Removal (CDR) have reduced GHGs sufficiently. Here, SRM, even when combined with high CDR, would come with century-long legacies of deployment, implying centuries of costs, risks and side effects.