Big Changes in North Atlantic Currents


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: 

DOES IT FEEL LIKE POLITICS IS AT A BREAKING POINT?

Headshot of Editor in Chief of Mother Jones, Clara Jeffery

It sure feels that way to me, and here at Mother Jones, we’ve been thinking a lot about what journalism needs to do differently, and how we can have the biggest impact.

We kept coming back to one word: corruption. Democracy and the rule of law being undermined by those with wealth and power for their own gain. So we're launching an ambitious Mother Jones Corruption Project to do deep, time-intensive reporting on systemic corruption, and asking the MoJo community to help crowdfund it.

We aim to hire, build a team, and give them the time and space needed to understand how we got here and how we might get out. We want to dig into the forces and decisions that have allowed massive conflicts of interest, influence peddling, and win-at-all-costs politics to flourish.

It's unlike anything we've done, and we have seed funding to get started, but we're looking to raise $500,000 from readers by July when we'll be making key budgeting decisions—and the more resources we have by then, the deeper we can dig. If our plan sounds good to you, please help kickstart it with a tax-deductible donation today.

Thanks for reading—whether or not you can pitch in today, or ever, I'm glad you're with us.

Signed by Clara Jeffery

Clara Jeffery, Editor-in-Chief

We Recommend

Latest

Sign up for our newsletters

Subscribe and we'll send Mother Jones straight 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

Share your feedback: We’re planning to launch a new version of the comments section. Help us test it.