Application of Hollow Glass Microspheres in the Arctic Ocean Would Likely Lead to a Deceleration of Arctic Sea Ice Loss” - A Critique of the Paper by Webster and Warren (2022)

Avoiding the worst effects of global warming requires a multipronged approach including decarbonizing as quickly as possible, adaptation, greenhouse gas removal, and climate intervention. Additional research is needed to ensure that climate intervention strategies will be safe, effective, and environmentally acceptable. The importance of the Arctic in influencing global climate has led investigators to propose various climate intervention strategies specific to the Arctic (Strawa et al., 2020, https://doi.org/10.1016/j.orbis.2020.08.010). One approach, proposed by Field et al. (2018, https://doi.org/10.1029/2018EF000820), is to distribute reflective hollow glass microspheres (HGM) on strategic areas of Arctic sea ice at strategic times to reduce ice melt, thereby slowing the Arctic ice-albedo feedback and interrupting further acceleration of ice melt. While research into this technique is still in its early stages, results show this approach can effectively slow melt of Arctic sea ice (Field et al., 2018, https://doi.org/10.1029/2018EF000820; Johnson et al., 2022, https://doi.org/10.1029/2022ef002883). On the other hand, a recent paper by Webster and Warren (2022, https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022EF002815) claims that this technique would warm the Arctic and speed up ice loss. Webster and Warren (2022), https://doi.org/10.1029/2022ef002815 largely ignore the promising results of field experiments conducted using hollow glass microspheres on pond ice (Field et al., 2018, https://doi.org/10.1029/2018EF000820; Johnson et al., 2022, https://doi.org/10.1029/2022ef002883) and instead present an analysis that hinges upon a very high absorptance value for HGM. In this commentary, we present new measurements of HGM and show that, when measurement uncertainty is accounted for, their model shows that deploying HGM as proposed by AIP can cool the Arctic and prolong Arctic sea ice.