Broken Arctic sea ice as seen from a window in from a U.S. Coast Guard flight over the Beaufort Sea in the Arctic Ocean in 2009. (Yereth Rosen/Reuters)
Big waves like those fit for surfing are not what we think of when contemplating the Arctic Ocean. The water is ice-covered most of the time — and it takes large expanses of open sea plus wind to produce mighty surf.
So the fact that researchers have now measured swells of more than 16 feet in the Arctic’s Beaufort Sea, just north of Alaska, is a bit of a stunner. Swells of that size, researchers say, have the potential to break up Arctic ice even faster than than the melt underway there for decades thanks to rapid global warming.
The wave measurements, using sensors beneath the surface communicating via satellite, were recorded by Jim Thomson of the University of Washington and W. Erick Rogers of the Naval Research Laboratory in 2012 and reported in an article in Geophysical Research Letters this year.
“The observations reported here are the only known wave measurements in the central Beaufort Sea,” they wrote, “because until recently the region remained ice covered throughout the summer and there were no waves to measure.”
Sixteen feet was the average during a peak period, Thomson said in an email. “The largest single wave was probably” 9 meters, or about 29 feet, he said. The average over the entire 2012 season was 3 to 6 feet.
Satellite images of polar ice sheets taken in 2001 and 2007 show retreating ice in the Beaufort Sea during summer in the Arctic Ocean. (Photo by USGS via Getty Images)
The distances of open water change “dramatically throughout the summer season, from essentially zero in April to well over 1000 km in September,” they reported. “In recent years, the seasonal ice retreat has expanded dramatically, leaving much of the Beaufort Sea ice free at the end of the summer.”
Because swells carry more energy, they reported, they will likely increase the pace of ice breakup in the region, eventually producing an “ice-free summer, a remarkable departure from from historical conditions in the Arctic, with potentially wide-ranging implications for the air-water-ice system and the humans attempting to operate there.”
“Waves could accelerate the ice retreat,” Thomson said in his email from a village on the Arctic, where he was getting read to deploy some wave buoys. “We don’t have much direct evidence of this, or knowledge of the relative importance compared with melting, but the process is real. We are conducting a large project this summer to answer just that question”