Big Changes in North Atlantic Currents

Facts matter: Sign up for the free Mother Jones Daily newsletter. Support our nonprofit reporting. Subscribe to our print magazine.


There’s an important paper in early view in PNAS describing profound changes in the dominant currents of the North Atlantic since the 1970s. What’s intriguing here—apart from the findings—is the method of determining these changes.

The authors used new technology to parse the story of ocean circulation from the story of ocean productivity using the skeletons of deepwater gorgonian corals. Specifically, they employed a process of amino acid analysis of nitrogen stable isotopes (δ15N-AA), as recorded in the growth rings of corals living between Newfoundland and Maine.

The technique promises to be a kind of Rosetta Stone for deciphering the ecological and physical history of the oceans.

A deep-water gorgonian coral. Image courtesy of Sanctuary Quest 2002, NOAA/OER.A deep-water gorgonian coral. Image courtesy of Sanctuary Quest 2002, NOAA/OER.

The results reveal a sharply declining influence of the Labrador Current (colder, less saline, and nutrient-poor) in favor of Gulf Stream waters (warmer, saltier, nutrient-rich) since the 1970s, compared to the previous 1,800 years. Image courtesy PNAS.Image courtesy PNAS.

The interplay between the Labrador Current and the Gulf Stream is a crucial component of the North Atlantic Oscillation, one of the major climate drivers for North America and Europe.

We therefore conclude that changes in nitrate source partitioning may be tied to recent, human-caused changes in global climate. These results highlight the importance of novel and creative proxies like δ15 N-AA for investigating the links between climate change and ecosystem functioning beyond the last few decades of scientific observations.

The paper:

  • Owen A. Sherwood, Moritz F. Lehmann, Carsten J. Schubert, David B. Scott, and Matthew D. McCarthy. Nutrient regime shift in the western North Atlantic indicated by compound-specific δ15N of deep-sea gorgonian coral. PNAS. January 3, 2011. DOI: 

THE END...

of our annual funding cycle is fast approaching, on June 30, and we have a considerable $230,000-plus gap in our online fundraising budget.

If you value the nonprofit journalism you get from Mother Jones, and you can, right now is an important time to help us keep charging hard with a much-needed and much-appreciated donation.

payment methods

THE END...

of our annual funding cycle is fast approaching, on June 30, and we have a considerable $230,000-plus gap in our online fundraising budget.

If you value the nonprofit journalism you get from Mother Jones, and you can, right now is an important time to help us keep charging hard with a much-needed and much-appreciated donation.

payment methods

We Recommend

Latest

Sign up for our free newsletter

Subscribe to the Mother Jones Daily to have our top stories delivered directly to your inbox.

Get our award-winning magazine

Save big on a full year of investigations, ideas, and insights.

Subscribe

Support our journalism

Help Mother Jones' reporters dig deep with a tax-deductible donation.

Donate