Washington, Oct 6 : A new NASA study has shown that the rising frequency and intensity of arctic storms over the last half century, attributed to progressively warmer waters, directly provoked acceleration of the rate of arctic sea ice drift, long considered by scientists as a bellwether of climate change.
NASA researcher Sirpa Hakkinen of Goddard Space Flight Center in Greenbelt, Maryland, and colleagues from Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, and the Arctic and Antarctic Research Institute, St. Petersburg, Russia, set out to confirm a long-standing theory derived from model results that a warming climate would cause an increase in storminess.
Their observational approach enabled them to not only link climate to storminess, but to also connect increasing trends in arctic storminess and the movement of arctic ice - the frozen ocean water that floats on the Arctic's surface.
"Gradually warming waters have driven storm tracks - the ocean paths in the Atlantic and Pacific along which most cyclones travel - northward. We speculate that sea ice serves as the 'middleman' in a scenario where increased storm activity yields increased stirring winds that will speed up the Arctic's transition into a body of turbulently mixing warm and cool layers with greater potential for deep convection that will alter climate further," said Hakkinen.
"What I find truly intriguing about confirming the link between the rise in storminess and increased sea ice drift is the possibility that new sinks for carbon dioxide may emerge from this relationship that could function as negative feedback for global warming," he added.
Hakkinen and colleagues analyzed 56 years of storm track data from earlier studies and annual data on atmospheric wind stress, an established indicator of storm activity, which is generated by the National Center for Atmospheric Research in Boulder, Colorado.
The data confirmed an accelerating trend in storm activity in the Arctic from 1950 to 2006.
Acknowledging ice as a harbinger of climate change, they next analyzed ice drift data collected during the same 56-year period from drifting stations and after 1979 from drifting buoys positioned around the Arctic that measured surface air temperature and sea level pressure.
The team found that the pace of sea ice movement along the Arctic Ocean's Transpolar Drift Stream from Siberia to the Atlantic Ocean accelerated in both summer and winter during the 55-year period.
The accelerating pace of sea ice drift coincided with an increase in wind stress.
Because the surface wind is known to be the "driving force" behind the movement of sea ice, they concluded that the increase in arctic storminess and the sea ice drift speeds are linked.