While it may not be surprising to learn that sea ice is melting, scientists were shocked to learn that in 2012 waves appeared in the Arctic Ocean and accelerated the shrinkage of already fragile ice. The height of these waves, however were a surprise at 16 feet in height, as high as a second-story window.
The area in question is Beaufort Sea, north of Alaska. Waves have never been measured here before because year-round sea ice prevented them from forming. Because of global warming, the area is now completely free of ice by the time September roles around. Sensors that are used here to measure the waves are designed specifically for monitoring wave height. Monitoring began in 2012, with the 16-foot readings coming during a September storm. There was 620 miles of open water on the day the wave was measured, garnering enough wind to cause such a massive swell. Wave size increases in accordance with the amount of open water over which the has to wind blow, which referred to as “fetch.” Jim Thomson, lead researcher on the study from the University of Washington in Seattle, attributes ice breakup that year to two particularly powerful tropical cyclones on the Atlantic Coast, one in August and another in September.
In the study, published in Geophysical Research Letters, scientists acknowledge that waves of that size are bigger than anything seen in Beaufort Sea before, but also acknowledge that the arctic ice has receded further than ever before also. 2012 was a record low year for summer melt, when ice shrank to 1.32 million square miles, according to the National Snow and Ice Data Center.
The appearance of waves is cause for concern because they accelerate arctic sea ice shrinkage through motion. The motion causes ice to break apart, and the more ice breaks apart, the more sunlight can seep in and warm the ocean. This cycle repeats itself, causing more warming, less ice, and more waves. Thomson, along with research partner Erik Rogers of the Naval Research Laboratory in Mississippi, predicts a worst case scenario caused by this repetitive cycle. They say it is conceivable that increased waves could send the Arctic “toward an ice-free summer.”
Bigger waves mean bigger problems. Current measurements of 16 foot waves sound like a lot, but if winds blow over open water, they produce higher waves. Less ice produces bigger waves. According to Darek Bogucki, an oceanographer specializing in the Arctic, waves of this size and bigger could become the new normal. Shorelines would be affected, speeding erosion and melting permafrost. Thomson warns while the melting has been occurring for the past decades, what’s happening with wave activity is new.
Thomson is currently at work adding more wave sensors to the Beaufort Sea to track wave heights, open water, and weather patterns. This continuing research is funded by U.S. Office of Naval Research.
Global warming has affected sea ice since the 1970s, but loss measurably accelerated since 2002. If waves continue to exacerbate ice shrinkage in the Arctic, that rate may accelerate further.
By Stacey Wagner