Physical oceanographers have different ideas on the mechanics of how more southerly water--and the things living in it--may arrive in the arctic. However, most agree that it will happen if climate keeps warming, said Arnold Gordon, head of Lamont's division of ocean and climate physics, who was not involved in the research. For one, a countercurrent running near Greenland, the North Atlantic Polar Gyre, normally wards off the Gulf Stream; but that gyre is predicted to slow with warming. Atlantic currents might also respond to changing wind patterns, or to the increasing fresh water now pouring into the northern ocean from melting sea ice and glaciers. Either way, this could draw more southerly water into the north, said Gordon.
Louis Fortier, an arctic oceanographer at Laval University in Quebec, said of the recent injections of southerly waters, "Whether or not [such] intrusions are signs of this predicted increased advection in response to climate change, nobody can tell yet, I believe. But for me, the observations so far certainly support the models." Paul Snelgrove, a specialist in cold-ocean studies at Memorial University of Newfoundland, agreed. "The question is, are these kinds of incursions becoming more frequent and stronger? If it continues, the case would become more persuasive. Right now, this study is not a definitive test, but it seems like an intriguing teaser as to what might happen."
Whatever the answer, this is the first time a living population of southern radiolaria has been found so far north. Radiolaria live only about a month, so it must have taken 80-some generations for some species to make the five- to seven-year trip, say the authors. On the way, successive generations could have adapted to colder waters. In 2009, the surface water in the sample a
|Contact: Kevin Krajick|
The Earth Institute at Columbia University