Tagged Narwhals Track Warming Near Greenland

Tagged nawhals migrated south into Baffin Bay
where they collected and transmitted temperatures
from the pack ice through the following spring.
Photo Credit: NOAA/University of Washington


Science Daily, October 27, 2010

In a research paper published online October 27 in the Journal of Geophysical Research Oceans, a publication of the American Geological Union (AGU), scientists reported the southern Baffin Bay off West Greenland has continued warming since wintertime ocean temperatures were last effectively measured there in the early 2000s.

Temperatures in the study were collected by narwhals, medium-sized toothed Arctic whales, during NOAA-sponsored missions in 2006 and 2007. The animals were tagged with sensors that recorded ocean depths and temperatures during feeding dives from the surface pack ice to the seafloor, going as deep as 1,773 meters, or more than a mile.

Scientists have had limited opportunities to measure ocean temperatures in Baffin Bay during winter months because of dense ice and harsh conditions. Cost is also a factor — it requires millions of dollars to mount a conventional expedition using an ice-breaking vessel and other specialized equipment and people. As a result, for the past decade, researchers used climatology data consisting of long-term historical average observations rather than direct ocean temperature measurements for winter temperatures in the area.

The published study reported that highest winter ocean temperature measurements in 2006 and 2007 from both narwhals and additional sensors deployed using helicopters ranged between 4 and 4.6 degrees Celsius (39.2 and 40.3 degrees Fahrenheit). The study also found that temperatures were on average nearly a degree Celsius warmer than climatology data. Whale-collected temperatures also demonstrated the thickness of the winter surface isothermal layer, a layer of constant temperature, to be 50 to 80 meters less than that reported in the climatology data.

“Narwhals proved to be highly efficient and cost-effective ‘biological oceanographers,’ providing wintertime data to fill gaps in our understanding of this important ocean area,” said Kristin Laidre from the Polar Science Center in the University of Washington’s Applied Physics Laboratory. “Their natural behavior makes them ideal for obtaining ocean temperatures during repetitive deep vertical dives. This mission was a ‘proof-of-concept’ that narwhal-obtained data can be used to make large-scale hydrographic surveys in Baffin Bay and to extend the coverage of a historical database into the poorly sampled winter season.”

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