Towering Waves Are a New Feature of the Increasingly Ice-Free Arctic
New shipping lanes may not have ice, but they will have a particularly deadly breed of wave.
Arctic shipping is among the most fully realized and realizable would-be silver linings of global warming. Already shippers are taking advantage of the mammoth shortcut represented by ice-free summers in the polar north, with ports opening all along this span of now-open water. There are, of course, no free lunches, and shippers may now be faced with a potentially dire downside to their good fortune: waves. Huge, potentially deadly swells are quick becoming a new feature of the Arctic, something people had never observed before in that body of water.
An open-access University of Washington study, published in the Geophysical Research Letters, claims the first such observation, made during a 2012 storm that unleashed house-sized, 16-foot waves across once ice-covered seas. The source of those waves, according to the paper, was not just regular wind, but the unceasing howls unique to the Arctic region. The observations come courtesy of a sensor anchored 50 meters below the surface of the central Beaufort Sea, some 350 miles north of Alaska's North Slope.
"The interaction of waves and ice is particularly complex, because ice can suppress waves by scattering and dissipating wave energy," the study explains, "while the waves simultaneously break up the ice." The result then is a feedback loop of sorts, in which decreasing ice results in increasing wave strength, which in turn results in further ice decreases. The Arctic may be ice-free sooner than first thought.
"Future scenarios for reduced seasonal sea ice cover in the Arctic suggest that larger waves are to be expected and that swells will be more common," the U of W paper continues. "Swells carry more energy and have longer attenuation scales within ice and thus will be more effective at breaking up the remaining ice. It is possible that the increased wave activity will be the feedback mechanism which drives the Arctic system toward an ice-free summer."
The current study dovetails in a rather spooky way with ongoing research probing changing storm/sea level conditions in the North Sea, which, while not properly Arctic, does reveal something about the post-ice future. A 2012 study in Ocean and Coastal Managementnoted, "for the future most projections point towards a moderate increase in storm activity in the area with corresponding changes in storm surge and wave climate. These changes will add to the expected future increase in mean sea level, leading to an increased hazard from extreme sea levels. The latter may have consequences for safety, especially in the low lying coastal areas in the Southern North Sea."
A new North Sea storm surge study was released this week with yet more ominous observations, made during a two-day 2013 storm event. That study describes the largest storm surge seen in 60 years in the North Sea, paired with the warning that "storm surge impacts on low-lying coasts threaten vulnerable human communities on a global scale." Indeed, while there's a cruel irony for shippers eyeing Arctic routes, the real cruelty is likely to be inflicted on regular people who happen to be residing just a bit too close to rising seas coupled with rising waves.