Uncertainties and confidence in stratospheric aerosol injection modelling: a systematic literature review

Abstract

Abstract Model projections performed to evaluate the efficacy and impacts of solar geoengineering interventions, such as Stratospheric Aerosol Injection (SAI), include multiple sources of uncertainty, namely scenario, model, and natural variability uncertainty. It is well accepted that a quantitative uncertainty assessment related to SAI modelling is required to provide robust and policy-relevant information on SAI. This study investigates how and to what extent articles using a climate modelling approach on SAI quantify and communicate uncertainty sources. We conducted a systematic literature review of a sample of 60 peer-reviewed articles in order to (i) analyse whether uncertainties were addressed, and if yes, which methods were used to characterize uncertainties, and (ii) study how the articles communicated assumptions and limits that contribute to the estimation of confidence in the used models and the resulting projections. We present statistics on the uncertainty quantification methods used in the articles and we discuss the vocabulary employed for conveying these uncertainties and model confidence. In the studied article sample, the attention paid to uncertainty estimations in the SAI literature increased with time, and overall, uncertainties were treated using a variety of methods. Model confidence was not always explicitly communicated as the models used are already tested in the literature and their strengths and weaknesses are known to the community although this is often implicit. Our results show that it is currently difficult to perform global, quantitative assessments of uncertainty related to SAI research, in line with recent review reports on solar geoengineering.