Bubbles On Ice

Illustration by Arina Kokoreva

A bit late considering the special issue was published one month ago, but here is another article in a recent series featuring unusual ideas about how to address climate change:

A Heat Shield for the Most Important Ice on Earth

Engineers might be able to protect Arctic ice by coating it with tiny glass bubbles. Should they?

An aerial view of the glass-bubble-covered ice, at left, and the bare ice. Photograph by Doug Johnson

On a clear morning in late March, in rural Lake Elmo, Minnesota, I followed two materials scientists, Tony Manzara and Doug Johnson, as they tromped down a wintry hill behind Manzara’s house. The temperature was in the high thirties; a foot of snow covered the ground and sparkled almost unbearably in the sunlight. Both men wore dark shades. “You don’t need a parka,” Johnson told me. “But you need sunglasses—snow blindness, you know?” At the bottom of the hill, after passing some turkey tracks, we reached a round, frozen pond, about a hundred feet across. Manzara, a gregarious man with bushy eyebrows, and Johnson, a wiry cross-country skier with a quiet voice, stepped confidently onto the ice.

Manzara and Johnson wanted me to see the place where, in a series of experiments, they had shown that it was possible to slow the pond’s yearly thaw. 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.)

At the edge of the pond, Manzara and Johnson started to reminisce. Originally, they had applied glass bubbles to a few square sections of the frozen pond, expecting that the brightest ice would last longest. But they found that, beneath the pond’s frozen surface, water was still circulating, erasing any temperature differences between the test and control sections. In subsequent years, they sank walls of plastic sheeting beneath the pond’s surface, and the coated ice started to last longer. At first, Johnson manually measured the ice thickness by donning a wetsuit and snowshoes, tying a rope around his waist, and walking onto the frozen surface with a drill and a measuring rod; he was relieved when they figured out how to take sonar measurements instead. Manzara directed my gaze to two trees on opposite shores. “This is where we set up the flying albedometer,” he said. An albedometer measures reflected radiation; theirs “flew” over the lake by way of a rope strung between two pulleys. By this point, I had been staring at the ice and snow for almost an hour, and my vision started to turn purple-pink. I blinked hard as we headed inside.

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.

That afternoon, Field arrived at Manzara’s house from California, where she runs a microtechnology-consulting company and teaches a Stanford course on climate change, engineering, and entrepreneurship. Like an old friend, she let herself in and called out hello. Field has let her shoulder-length hair go completely silver, “in solidarity with the Arctic,” she joked; when we sat down together, it was obvious that all three scientists relished engineering challenges, from applying the glass bubbles (shake them out of giant cannisters? spray them from a pressure pot?) to measuring their effects. They are an inventive bunch. Both Johnson and Manzara were senior scientists at 3M: Johnson, a physicist, worked on advanced materials such as a high-capacity transmission cable, to stabilize electrical grids; Manzara, an organic chemist, focussed on energetic materials, making ingredients for flares and rocket propellants. Field holds more than sixty patents; Johnson around twenty; Manzara around twelve…

Read the whole article here.

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