Solar Geoengineering in the Polar Regions: A Review

Abstract

Rapid and deep reductions in greenhouse gas emissions are necessary to limit the harm to people around the world expected due to climate change over the 21st Century (IPCC, 2022). However, increasing awareness of the failure of global climate policy to bring about the rate of change in the global economic system necessary to meet the 1.5°C global warming level (van de Ven et al., 2023; UN Environment Programme, 2022;Sognnaes et al., 2021) identified in the Paris Agreement (UNFCCC, 2015) has led some to consider the use of solar geoengineering-the deliberate cooling of the planet by reflecting away incoming sunlight-to reduce these harms (National Academies of Sciences, Engineering, and Medicine, 2021). Such consideration has been made more urgent by the large changes in the climate system already observed at 1.1°C of warming (Gulev et al., 2021), changes which are particularly stark in the polar regions (Pörtner et al., 2019). Recent work has demonstrated the significant risk that several cryospheric tipping elements in the Earth system, including abrupt boreal permafrost thaw, and collapse of the West Antarctic Ice Sheet, may become active at global temperatures below the Paris

An assessment of the infrastructural and temporal barriers constraining a near-term implementation of a global stratospheric aerosol injection program

“…• Injection altitude of 21.5 km These are not the only plausible parameters by which an SAI program might be defined. Several recent papers have described deployments at high latitudes to restrain tipping elements or ice loss at the poles (Lee et al 2021, Smith et al 2022b, Xie et al 2022, Duffey et al 2023, Goddard et al 2023, Sutter et al 2023. Others have considered regional interventions at lower altitudes intended to manage heat waves rather than average annual temperatures (Bernstein et al 2013, Mulena et al 2019, Zhao et al 2019.…”

The interaction of Solar Radiation Modification and Earth System Tipping Elements

“…Under the GeoMIP scenarios G3 and G4, SAI delays the loss of sea ice but this is not sufficient to prevent the loss of almost all September sea ice in most models (Berdahl et al , 2014) . However, it is likely that this is due to insufficient cooling, and that a world at the same global mean temperature without SRM would also lose all September sea ice in these models (Duffey et al , 2023) .…”

“…For example, one SRM scenario sees 50% more sea-ice extent at the September minimum than the control case (at the same global mean temperature without SRM), but 8% less extent at the March maximum (Jiang et al , 2019) . This is linked to a general under-cooling of the polar winter by SRM, and an associated suppression of the seasonal cycle at high latitudes (Jiang et al , 2019 ;Duffey et al , 2023 ). However, modelling of SRM shows at least partial effectiveness at increasing winter sea ice and reducing local winter near-surface air temperatures (Berdahl et al , 2014 ;Jiang et al , 2019 ;Lee et al , 2021;Lee et al , 2023 ).…”

“…Additionally, there has been little work, except the study of (Ridley and Blockley, 2018) , quantifying the change in Arctic climate and sea ice under SRM with comparison to the expected change at the level of global warming under that SRM scenario. As such, further research is required to quantify the effectiveness of different SRM strategies for Arctic restoration (Duffey et al , 2023) .…”

Different Strategies of Stratospheric Aerosol Injection Would Significantly Affect Climate Extreme Mitigation

“…Numerous modeling studies have made efforts to examine the effects of SRM on various aspects of the Earth system, including temperature, the hydrologic cycle, large-scale ocean circulation, the cryosphere, and the carbon cycle (refer to Irvine et al (2016), NASEM (2021), Lee, Marotzke, et al (2021), and Duffey et al (2023) for a review of relevant studies). Some previous studies examined the impact of SRM on climate extremes.…”