Complementing CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; emission reduction by solar radiation management might strongly enhance future welfare

Koen G Helwegen,Claudia E Wieners,Henk A Dijkstra,Jason E Frank

doi:10.5194/esd-10-453-2019

Complementing CO&lt;sub&gt;2&lt;/sub&gt; emission reduction by solar radiation management might strongly enhance future welfare

Koen G Helwegen, Claudia E Wieners + Show 2 more

Open Access

https://doi.org/10.5194/esd-10-453-2019

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Abstract

Abstract. Solar radiation management (SRM) has been proposed as a means to reduce global warming in spite of high greenhouse-gas concentrations and to lower the chance of warming-induced tipping points. However, SRM may cause economic damages and its feasibility is still uncertain. To investigate the trade-off between these (economic) gains and damages, we incorporate SRM into a stochastic dynamic integrated assessment model and perform the first rigorous cost–benefit analysis of sulfate-based SRM under uncertainty, treating warming-induced climate tipping and SRM failure as stochastic elements. We find that within our model, SRM has the potential to greatly enhance future welfare and merits being taken seriously as a policy option. However, if only SRM and no CO2 abatement is used, global warming is not stabilised and will exceed 2 K. Therefore, even if successful, SRM can not replace but only complement CO2 abatement. The optimal policy combines CO2 abatement and modest SRM and succeeds in keeping global warming below 2 K.

Highlights

Despite the Paris Agreement target to keep global mean temperature change “well below 2 K” in order to prevent “dangerous climate change” (UNFCCC, 2015), no decisive reduction of CO2 emissions has yet taken place (Le Quéré et al, 2018)
This illustrates the potential use of Solar radiation management (SRM) as a transition technology, especially under ambitious abatement: SRM can be used for a limited time in modest strength to cut off a warming overshoot
We present the first cost–benefit analysis of SRM under uncertainty performed with a rigorous optimisation approach

Summary

Introduction

Despite the Paris Agreement target to keep global mean temperature change “well below 2 K” in order to prevent “dangerous climate change” (UNFCCC, 2015), no decisive reduction of CO2 emissions has yet taken place (Le Quéré et al, 2018). The scheme involves injecting precursor gases such as SO2 into the stratosphere This leads to the formation of reflective sulfate aerosols in the lower stratosphere which increases the Earth’s albedo and causes surface cooling. Such cooling – of about 0.4 K over several years (Stowe et al, 1990; Thompson et al, 2009) – was observed following the Pinatubo eruption (Stowe et al, 1990; Thompson et al, 2009; Stenchikov et al, 1998; Robock, 2000), which injected 8–10 Mt(S) (megatonnes of sulfur), mainly as SO2, into the stratosphere (Ward, 2009).

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