Editing IPCC:AR6/SR15/Chapter-4 (section)

==== 4.3.8.2 Economic and technological feasibility ====

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The literature on the engineering costs of SRM is limited and may be unreliable in the absence of testing or deployment. There is ''high agreement'' that costs of SAI (not taking into account indirect and social costs, research and development costs and monitoring expenses) may be in the range of 1–10 billion USD yr <sup>−1</sup> for injection of 1–5 MtS to achieve cooling of 1–2 W m <sup>−</sup> <sup>2</sup> (Robock et al., 2009; McClellan et al., 2012; Ryaboshapko and Revokatova, 2015; Moriyama et al., 2016) <sup>[[#fn:r761|761]]</sup> , suggesting that cost-effectiveness may be high if side-effects are low or neglected (McClellan et al., 2012) <sup>[[#fn:r762|762]]</sup> . The overall economic feasibility of SRM also depends on externalities and social costs (Moreno-Cruz and Keith, 2013; Mackerron, 2014) <sup>[[#fn:r763|763]]</sup> , climate sensitivity (Kosugi, 2013) <sup>[[#fn:r764|764]]</sup> , option value (Arino et al., 2016) <sup>[[#fn:r765|765]]</sup> , presence of climate tipping points (Eric Bickel, 2013) <sup>[[#fn:r766|766]]</sup>   and damage costs as a function of the level of SRM (Bahn et al., 2015; Heutel et al., 2018) <sup>[[#fn:r767|767]]</sup> . Modelling of game-theoretic, strategic interactions of states under heterogeneous climatic impacts shows ''low agreement'' on the outcome and viability of a cost-benefit analysis for SRM (Ricke et al., 2015; Weitzman, 2015) <sup>[[#fn:r768|768]]</sup> .

For SAI, there is ''high agreement'' that aircrafts could, after some modifications, inject millions of tons of SO <sub>2</sub> in the lower stratosphere (at approximately 20 km; (Davidson et al., 2012; McClellan et al., 2012; Irvine et al., 2016) <sup>[[#fn:r769|769]]</sup> .

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