For the first time, waves as tall as 16 feet have been recorded in Arctic waters. If these waves are speeding the breakup of the region's remaining ice, as oceanographers suspect, they could signal the birth of a feedback mechanism that will hasten the Arctic's march toward an ice-free summer.
Above: Ocean waters transition from solid to liquid in the Arctic summer | Photo Credit: Patrick Kelley, U.S. Coast Guard via USGS
One way to produce waves is to combine wind, time, and water. Wind that blows strong and long enough over a large enough surface of water can generate whitecaps, which give rise to small swells, which in turn consolidate into big, heavy waves.
Back when Arctic sea ice receded as little as 100 miles every summer, there was little water to work with, when it came to generating waves. But in the warming North, sea ice is retreating. Meanwhile, regions of open water are expanding. In the summer of 2012, the Arctic surrendered more than 1,000 miles of coastal ice to liquid ocean. When it did, the region's persistent summertime winds gained a new and powerful purchase on the vast stretches of open water.
During a September 2012 storm, University of Washington Researcher Jim Thomson detected wind-generated waves as high as 5-meters tall. While researchers have known about Arctic melting for decades, Thomson says in a statement what we're seeing with waves of this size "is potentially a new process, a mechanical process, in which the waves can push and pull and crash to break up the ice." As he notes, in the latest issue of Geophysical Research Letters (emphasis added):
It is possible that the increased wave activity will be the feedback mechanism which drives the Arctic system toward an ice-free summer. This would be a remarkable departure from historical conditions in the Arctic, which potentially wide-ranging implications for the air-water-ice system and the humans attempting to operate there. The increasing wave climate will also have implications for the coasts, which are already eroding rapidly during summer months as a result of climate change and subsequent loss of permafrost.
Thomson says that "at this point, we don't really know relative importance of these processes in future scenarios," so it's difficult to say what those implications are. Thomson and his colleagues hope to learn more this summer by deploying wave-sensing instruments like the one pictured here, all along Alaska's northern coast.
For those who measure Arctic Ocean waves, Thomson says "it's going to be a quantum leap in terms of the number of observations, the level of detail and the level of precision."
Read Thomson's full study at Geophysical Research Letters.