Glass beads cannot save Arctic sea ice | Polarjournal
The surface of Arctic sea ice is very heterogeneous and thus also exhibits variable reflectivity. Microglass beads are supposed to increase reflectivity and prevent melting, according to a 2018 study, but they do the opposite. Photo: Julia Hager

The worldwide, drastic reduction of greenhouse gas emissions would be THE measure to limit global warming. However, we as humanity are far from success in this regard. No wonder, then, that engineers and researchers are also trying to curb climate change with new technologies and active manipulation of the Earth system. One such geoengineering idea was to deploy glass microspheres on Arctic sea ice to increase the reflectivity of the ice and grow it into highly reflective perennial ice. However, a recent study led by the University of Alaska Fairbanks and published in the journal Earth’s Future has now shown that the glass beads have the opposite effect, melting the ice faster.

The tiny hollow glass spheres, the thickness of a human hair, were expected to lower temperatures in the Arctic, cause multi-year sea ice to form and thus reduce temperature increases in the Arctic and globally, according to a 2018 study.

Sea ice plays a critical role in Earth’s climate, reflecting most of the sun’s energy back into space, helping to regulate ocean and air temperatures and influencing ocean currents. According to the study, higher reflectivity of sea ice could slow down global warming.

But spreading multiple layers of glass beads on young sea ice is not the appropriate method to achieve this, according to the current study. Rather, it demonstrated that the hollow glass microspheres would darken the surface of the ice, accelerate the loss of sea ice, and further warm the climate.

Melt ponds absorb more solar energy and would theoretically be suitable sites to deploy the microspheres. However, an experiment showed that the beads are driven to the edge and clump together. Photo: Melinda Webster/University of Alaska Fairbanks

Although the glass beads absorb only 10 percent of sunlight, that energy is enough to accelerate ice melt and further warm the atmosphere over the Arctic, Webster found.

“Our results show that the proposed effort to halt Arctic sea-ice loss has the opposite effect of what is intended,” said Melinda Webster of the University of Alaska Fairbanks. “And that is detrimental to Earth’s climate and human society as a whole.”

Webster and her University of Washington colleague Stephen G. Warren calculated solar energy changes for eight common surface conditions on Arctic sea ice, each with different reflectance levels, which was not accounted for to the extent in the 2018 study. In addition, Webster and Warren also considered seasonal sunlight, the intensity of solar radiation at the surface and in the upper atmosphere, cloud cover, and the response of microspheres to sunlight.

They concluded that a layer of the glass beads can increase the reflectivity of thin, new ice that is naturally dark. However, the effect would be minimal because thin ice usually occurs in the fall and winter when there is little or no sunlight. Snow falling on the thin ice increases the reflectivity of the surface anyway.

Newly formed sea ice, also called pancake ice, appears dark and absorbs more sunlight than thick, perennial ice with a snow cover. Photo: Melinda Webster/University of Alaska Fairbanks

In spring, when more solar energy is available again, deep, reflective snow covers the sea ice. Additional microspheres applied would darken the snow and accelerate melting.

It is also not practical to use the microspheres on melt ponds in late spring and summer, even though they naturally have low reflectivity. An experiment conducted as part of the 2018 study showed that the beads are driven to the edge by the wind, where they clump together.

Thus, the seemingly most useful time to apply the microspheres – March, April, May, June, when solar radiation increases – is actually the worst.

And even if the microspheres absorbed no solar energy at all and truly prevented melting, the cost of deployment would be immense: 360 million tons of them would be needed for one application per year, which in turn is not feasible without causing climate-damaging emissions, not to mention the ecological impact of the foreign bodies in the Arctic ecosystem.

“The use of microspheres as a way to restore Arctic sea ice isn’t feasible,” Webster said. “While science should continue to explore ways to mitigate global warming, the best bet is for society to reduce the behaviors that continue to contribute to climate change.”

Julia Hager, PolarJournal

Link to the study: 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.

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