An aerial view of the glass-bubble-covered ice, at left, and the bare ice. Photograph by Doug Johnson.
Excerpt from this story from the
New Yorker:
Starting in the winter of 2012, working with a colleague named Leslie Field, they had covered some of the ice with glass microspheres, or tiny, hollow bubbles. Through the course of several winters, they demonstrated that the coated ice melted much more slowly than bare ice. An array of scientific instruments explained why: the spheres increase the ice’s albedo, or the portion of the sun’s light that the ice bounces back toward the sky. (Bright surfaces tend to reflect light; we take advantage of albedo, which is Latin for “whiteness,” when we wear white clothes in summer.)
Manzara, Johnson, and Field want to prove that a thin coating of reflective materials, in the right places, could help to save some of the world’s most important ice. Climate scientists report that polar ice is shrinking, thinning, and weakening year by year. Models predict that the Arctic Ocean could be ice-free in summer by the year 2035. The melting ice wouldn’t just be a victim of climate change—it would drive further warming. The physics seem almost sinister: compared with bright ice, which serves as a cool topcoat that insulates the ocean from solar radiation, a dark, ice-free ocean would absorb far more heat. All of this happens underneath the Arctic summer’s twenty-four-hour sun. But the fragility of the Arctic cuts both ways: as much as the region needs help, its ecosystems are sensitive enough that large-scale interventions could have unintended consequences.
Last year, Johnson, Manzara, Field, and other collaborators published a paper about their work at the test pond in Earth’s Future, a journal of the American Geophysical Union. It described how they segmented the pond, applied a thin layer of glass bubbles on one side, and set up instruments to measure water temperature, ice thickness, weather, and long-wave and short-wave radiation. Albedo measurements range from zero, for perfect absorption, to one, for mirrorlike reflection; the bubbles raised the albedo of late-winter pond ice from 0.1-0.2 to 0.3-0.4. After a February snowfall, they wrote, it was impossible to see any difference between the sections. But in March the snow thinned to reveal two distinct regions of ice, which melted at different rates as the days warmed. When the bare ice was gone, nine inches remained under the glass bubbles.
No amount of glass spheres or roofing granules will reverse climate change. Only a rapid global shift away from fossil fuels is likely to achieve that. But in a place like the Arctic, which is warming four times faster than the rest of the planet, and where the end-of-ice tipping point hangs like the Sword of Damocles, such an intervention could offer a precious lifeline: time. What kind of progress could the world make if the emergency receded by a few years? “You only need to treat a small portion of the Arctic to get a big impact on the global climate. That’s the big picture,” Johnson said, describing his group’s modelling. “You can get twenty-five years longer to keep the ice.”
