Scientists at Cornell University and Rutgers University said the severe loss of summertime arctic sea ice has increased the frequency of atmospheric blocking events like the one that steered Hurricane Sandy west into the densely populated New York City area.
The decrease in sea ice appears to enhance Northern Hemisphere jet stream meandering and intensify arctic air mass invasions toward middle latitudes, leading to the increase in blocking, they said.
Such a strong atmospheric, high-pressure blocking pattern over Greenland and the northwest Atlantic Ocean prevented Sandy from steering northeastward and out to sea like most October hurricanes and tropical storms from the Caribbean, the researchers said.
Instead, Sandy traveled up the Atlantic Coast and turned left "toward the most populated area along the Eastern Seaboard" and converged with an extratropical cyclone that transformed it into a monster tempest, the scientists said.
"If one accepts this evidence and ... takes into account the record loss of arctic sea ice this past September, then perhaps the likelihood of greenhouse warming playing a significant role in Sandy's evolution as an extratropical superstorm is at least as plausible as the idea that this storm was simply a freak of nature," the researchers wrote in the journal Oceanography.