[Image above] The hollow glass microspheres that are meant to protect sea ice but will likely hasten its melting instead. Credit: Ned Rozell, University of Alaska Fairbanks
For years we heard that climate tipping points would soon be reached, but those claims grew much more immediate in 2022. Following release of the Sixth Assessment Report by the Intergovernmental Panel on Climate Change, United Nations Secretary-General António Guterres unequivocally claimed we passed the point of no return during his remarks at the General Assembly’s fifth consultation in March.
As the realities associated with a changing climate become abundantly clear, some researchers and government officials argue cutting emissions is no longer enough to combat the drastic changes. Instead, they believe geoengineering is the only solution.
Geoengineering refers to a set of emerging technologies that enable deliberate, large-scale intervention in the Earth’s natural systems to counteract climate change. These technologies are generally categorized as either “solar radiation management” (reflect some of the sun’s energy back into space) and “greenhouse gas removal” (remove carbon dioxide or other greenhouse gases from the atmosphere).
Understandably, the idea of tinkering with Earth’s natural systems have another set of researchers and government officials concerned such techniques will ultimately worsen the climate situation. They emphasize the need to fully consider possible consequences before implementing geoengineering technologies.
A recent open-access paper demonstrates the divide between these two viewpoints on geoengineering.
The paper is written by Melinda Webster at the University of Alaska Fairbanks and Stephen Warren at the University of Washington. Their study warns that a proposal to protect Arctic sea ice through geoengineering could ultimately hasten its loss instead.
That proposal, which we reported on CTT in 2019, grew from the fact that Arctic sea ice experienced substantial decline in the past 40 years. This loss is due to a positive feedback loop, in which dark ocean water absorbs solar energy and warms, causing ice to melt. The more ice melts and the more water opens to the sun, the faster the warm/melt cycle takes place. See the video below for more information on feedback loops in the Arctic.
The loss of sea ice concerned Leslie Field, a chemical and electrical engineer, and she founded a nonprofit organization called Ice911 (now called Arctic Ice Project) to test materials that could be added to sea ice to increase its albedo, i.e., ability to reflect sunlight.
In 2018, Leslie and her team published an open-access paper on hollow silica glass microspheres that they said could be spread on sea ice to increase its albedo and thus help conserve the ice.
When they presented their work at the University of Alaska Fairbanks to other scientists working on sea ice, a few expressed doubts about the project’s feasibility. For example, oceanographer Seth Danielson noted in a University of Alaska Fairbanks article that using an icebreaker to distribute the beads would decrease the reflectiveness of the pack ice field as the ship broke through, counteracting the purpose of the beads.
Field has since left the Artic Ice Project to found a new nonprofit called Bright Ice Initiative. However, University of Alaska Fairbanks researchers have not forgotten the glass microspheres project. The new paper by Webster and Warren confirms some of the hesitations that university researchers expressed back in 2019.
They begin by critiquing the experimental design used in the 2018 paper. Specifically, they point out that that paper investigated the albedo of thin ice with no snow cover, “but that surface type occurs on the Arctic Ocean mostly during times of the year when sunlight is minimal and the albedo is therefore irrelevant.”
So, “To estimate the radiative forcing achievable by spreading HGMs [hollow glass microspheres] over the Arctic Ocean, we must consider the various surface types that are largely representative of Arctic sea ice, with their spectral albedos, and how their seasonal cycles relate to the seasonal cycle of sunlight,” they write.
When seasonal differences in the sea ice surface are considered, Webster and Warren found the glass microspheres actually hasten melting.
While the glass microspheres reflect 43% of the incoming sunlight and allow 47% to pass through, the remaining 10% is absorbed. This absorption means the glass microspheres darken any surfaces with an albedo of more than 0.61, such as snow-covered ice.
“The net result is the opposite of what was intended: spreading HGMs would warm the Arctic climate [by an annual average of 3.3–3.5 Wm−2] and speed sea-ice loss,” they write.
If nonabsorbing glass microspheres were developed—and could be transported and distributed over the Arctic without contamination—then this method could help cool the climate, Webster and Warren write. However, the challenge then becomes one of quantity. About 360 million tons would be needed for an annual one-time application to cool the climate.
Ultimately, “The use of microspheres as a way to restore Arctic sea ice isn’t feasible,” Webster says in a University of Alaska Fairbanks press release. “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.”
The open-access paper, published in Earth’s Future, is “Regional geoengineering using tiny glass bubbles would accelerate the loss of Arctic sea ice” (DOI: 10.1029/2022EF002815).