The Hot Zone

Arctic waters warmest in 2,000 years

Posted by Alison Hawkes on January 31, 2011
Category : Climate Science and Scientists, The Oceans

On the heels of a study showing that Arctic ice is highly susceptible to warm water fluxes from the Atlantic Ocean, comes a new one estimating that Arctic waters are the warmest they’ve been in 2,000 years.

The interesting thing about this study, published in the journal Science this week, is that it looked at the history of tiny amoeboid protists called planktic foraminifers to tell the story. The remains of these creatures in sediment cores on the western edge of Svalbard, in Norway, were counted and species type was determined at mid-summer month intervals going back in time.

Sediment samples came from below the waters of the Fram Straight, the major passageway where Arctic sea ice meets warm Atlantic waters. Photo: Fruchtzwerg's World on Flickr

Researchers led by Robert Spielhagen from the Academy of Sciences, Humanities, and Literature in Mainz, Germany found a dramatic increase in sub-polar species appearing in the last century. Whereby sub-polar species accounted for 10 to 40 percent of the species count prior to 1900, they now account for some 60 percent of species present. The researchers call it “an unprecedented inversion of the subpolar/polar species ratio.”

The measurements of these species allowed the researchers to tabulate water temperatures of between 5 and 8 degrees Fahrenheit prior to 1850. Temperatures jumped to 6-10 degrees Fahrenheit after 1890, an average difference of about 3.6 degrees. The researchers point out that the warming they predict for the past 120 years matches the observational record and the results as a whole show a unique warming trend.

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