SPCMSC Research Geologist publishes journal article describing a new multi-century record using clam shells as proxy for northern North Atlantic marine climate

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USGS Research Geologist Madelyn Mette led a recent manuscript with coauthors in academia, titled “Persistent multidecadal variability since the 15th century in the southern Barents Sea derived from annually resolved shell-based records.”

Epoxy-mounted shell cross sections

Arctica islandica shells have been sectioned with a saw and embedded in epoxy for further analysis. (Credit: Madelyn Mette, USGS. Public domain.)

The paper is now published in The Journal of Geophysical Research: Oceans.

In the North Atlantic Ocean, multidecadal variability in sea surface temperatures over the past few centuries has largely been inferred through terrestrial proxies and decadally-resolved marine proxies. Annually-resolved records from marine proxy archives are especially rare from high latitude environments. We constructed an approximately 500 year continuous, absolutely-dated record of shell growth and oxygen isotope ratio for the ocean quahog species, Arctica islandica, collected from the coastal region of northern Norway. A sea surface temperature reconstruction using the shell-based data suggests an increase of at least 2 °C from the mid-18th century to 2014. Spectral analysis of the shell growth and isotope records supports evidence for Atlantic Multidecadal Variability (65–80 year periodicity) extending into polar and subpolar latitudes for the past five centuries. These results provide additional evidence that variability in sea surface temperatures is a persistent feature of the North Atlantic marine system. The shell-based records provide valuable new data that establish baseline marine climate variability in the southern Barents Sea region and valuable information that is important for predicting future climate.