John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
Snow depth on sea ice has fallen by as much as half in the past 50 years.
There was once a time when the Arctic rocked a full, glorious coat of snow. But the region has lately experienced a bout of icy balding, losing as much as half the depth of snow that usually accumulates on sea ice during the spring.
Arctic snow helps protect the underlying ice from melting under the sun and plays important roles in the survival of wildlife of all sizes. Scientists have long had an interest in its fluctuations, with the Soviets being among the first to measure it with meter sticks in the 1950s. More recently, researchers have conducted flyovers and detailed ground surveys to examine the disappearing snow. In the western Arctic, springtime accumulations have gone from 14 inches to 9 inches today, and in the Beaufort and Chukchi seas around Alaska from 13 inches down to a mere 6.
The stunning loss of snow is detailed in a new study from NASA, the University of Washington, and others (the full paper is behind a paywall at the Journal of Geophysical Research ). The scientists believe there's less snow because the seas are freezing later in the year, and "heavy snowfalls in September and October now fall into the open ocean," writes NASA. Says one of the space agency's scientists who participated in the study, Son Nghiem: "We knew Arctic sea ice was decreasing, but the snow cover has become so thin that its shield has become a veil."
This hot year will probably not help the Arctic pack on more snow, at least around Alaska. The state has breezed through its second warmest January-to-July period since the start of record-keeping in 1918, according to the National Climatic Data Center. Last month unusual heat bubbles formed over many places, such as the Alaska Peninsula and the west coast of the Gulf of Alaska. A new record for warmth was established in Cold Bay, as shown in this NCDC monthly summary, which also illuminates the cursed long-term heat plaguing the contiguous West:
How will thinning sea-ice snow affect future life? Here are some potential impacts from the University of Washington:
What thinner snow will mean for the ice is not certain. Deeper snow actually shields ice from cold air, so a thinner blanket may allow the ice to grow thicker during the winter. On the other hand, thinner snow cover may allow the ice to melt earlier in the springtime.
Thinner snow has other effects, [UW researcher Melinda] Webster said, for animals that use the snow to make dens, and for low-light microscopic plants that grow underneath the sea ice and form the base of the Arctic food web.