I am not sure I understand this.
Are you saying solar absorptance of the air in the microscopic bubbles
are less than 0.0001?
Hashem
Quoting Russell Seitz <[email protected]>:
"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.
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