Unicorns of the sea recruited to track warming

Global Warming Narwhals
A pod of narwhals swims off the coast of northern Canada. Kristin Laidre / University of Washington via AP
/ Source: The Associated Press

Most climate researchers use weather balloons, satellites, deep-sea submersibles or ice-drilling rigs to mine their data on global warming. A biologist at the University of Washington has turned to a more inventive method: attaching instruments to the backs of narwhals, marine mammals with unicorn-like tusks that live in arctic seas.

Kristin Laidre and her colleagues at the Polar Science Center at the UW's Applied Physics Laboratory have tagged three of the creatures with satellite transmitters that track the animals' movements and measure water temperatures in a region where researchers believe rapid warming is taking place.

The narwhals dive as deep as one mile to feed on bottom fish and already have provided the first winter temperature measurements in Baffin Bay between Canada and Greenland.

"We've converted these animals into oceanographers," Laidre told The Seattle Times by phone from Greenland.

Currents that flow through Baffin Bay moderate the weather in northern Europe by bringing warmer waters north. An international panel of climate scientists has predicted that global warming will slow those currents.

"Any weakening of the Gulf Stream because of climate change will immediately show up in this area," said Laidre's collaborator, Mads Peter Heide-Jrgensen of the Greenland Institute of Natural Resources.

Plugging the 'data hole'
Scientists say global climate models for the ocean west of Greenland have basically relied on guesswork. "There's just a huge data hole in this part of the world ocean in the winter," said Michael Steele, a senior oceanographer at the Polar Science Center.

After several years of expansion, the sea ice west of Greenland is now declining rapidly. When scientists flew over central Baffin Bay earlier this month, they found only open water.

"This is a very sensitive region in terms of climate change," said Andrew Weaver, a climate expert at the University of Victoria in British Columbia. He is not involved in the narwhal project, but called the technique "a totally fascinating approach."

Narwhals are difficult to study, not only because they inhabit the world's iciest oceans but also because they're skittish and, weighing in at a ton or more, tough to trap.

To catch them, scientists string long nets perpendicular to the shore then wait for the sea beasts to swim into the nets. "You can sit for many weeks with your net in the water and never see them," Laidre said.

When a narwhal gets entangled, it fights furiously until it's wrestled into a kind of hammock strung between two inflatable boats. Then scientists clip a transmitter smaller than a deck of cards to the animal's small dorsal fin.

400 data points daily
The three narwhals that scientists are tracking now were trapped last summer. Each one transmits more than 400 temperatures and depth measurements daily.

For the second phase of the project, which just wrapped up, a physicist lowered an oceanographic instrument into the water that provides more detail than the sensors on the narwhals, including salinity.

The narwhal project is funded by the National Oceanic and Atmospheric Administration's Office of Ocean Exploration and the Greenland Institute of Natural Resources.

In addition to oceanographic data, the studies are shedding light on the narwhal's life. Laidre, for example, has observed that the whales create what look like mole hills by pushing through thin ice to create breathing holes.

The project has not addressed the question that has long vexed narwhal-watchers: What is the purpose of the tusk?

Some researchers have found millions of nerve channels on the surface of the tusk — actually an elongated tooth — and have concluded it must be a sensory organ used by males to detect changes in temperature or air pressure.

However, Laidre and Heide-Jrgensen point out that females lack tusks, yet live longer on average than males, leading them to believe the tusk can't be critical for survival.