NOAA-Funded Tagging of Narwhals Finds Continued Warming of Southern Baffin Bay

SHip and iceberg

Credit: NOAA / University of Washington
An image from the expedition to the narwhal summering grounds in Melville Bay, West Greenland.

10/27/2010

In a research paper published in the Journal of Geophysical Research Oceans, scientists report 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 National Oceanic and Atmospheric Administration-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, as it costs 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 reports 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.”

 Read the rest of the story here.