"If non-absorbing HGMs could be manufactured, and if they could be transported and distributed without contamination by dark substances, they could cool the climate. "
I agree, especially since in contrast to the floating glass microspheres Webster and Warren reject, the solar radiation absorbance of the air in microscopic bubbles is roughly four orders of magnitude smaller than that of glass. On Saturday, October 8, 2022 at 9:51:11 AM UTC-4 Alan Robock wrote: > Webster, M. A., & Warren, S. G. (2022). Regional geoengineering using tiny > glass bubbles would accelerate the loss of Arctic sea ice. *Earth's > Future*, 10, e2022EF002815. https://doi.org/10.1029/2022EF002815 > > https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF002815 > > *Abstract* > Arctic sea ice might be preserved if its albedo could be increased. > To this end, it has been proposed to spread hollow glass microspheres > (HGMs) over the ice. We assess the radiative forcing (RF) that would > result, by considering the areal coverages and spectral albedos of eight > representative surface types, as well as the incident solar radiation, > cloud properties, and spectral radiative properties of HGMs. > HGMs can raise the albedo of new ice, but new ice occurs in autumn > and winter when there is little sunlight. In spring the ice is covered by > high-albedo, thick snow. In summer the sunlight is intense, and the snow > melts, so a substantial area is covered by dark ponds of meltwater, which > could be an attractive target for attempted brightening. However, prior > studies show that wind blows HGMs to the pond edges. > A thin layer of HGMs has about 10% absorptance for solar radiation, > so HGMs would darken any surfaces with albedo >0.61, such as snow-covered > ice. The net result is the opposite of what was intended: spreading HGMs > would warm the Arctic climate and speed sea-ice loss. > If non-absorbing HGMs could be manufactured, and if they could be > transported and distributed without contamination by dark substances, they > could cool the climate. The maximum benefit would be achieved by > distribution during the month of May, resulting in an annual average RF for > the Arctic Ocean of -3 Wm-2 if 360 megatons of HGMs were spread onto the > ice annually. > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/1859bec4-ef57-431e-850d-0d71ad51aec6n%40googlegroups.com.
