Narwhals: Nature's Climatologists

Narwhals look like mythical creatures. Captivating and curious. Seemingly part whale and part unicorn, complete with a ten-foot horn. Did you know the horn is actually their left front tooth growing through the narwhal’s upper lip?

Although very real animals, narwhals are elusive like mythical beings—such as fairies, leprechauns, and mermaids. They live in the remote Arctic oceans surrounding Greenland, Canada, Norway, and Russia. Narwhals can swim easily under Arctic ice because they lack dorsal fins (the fins that sit on top of fish, dolphins, and whales). And they can dive one mile below the ocean’s surface — deeper than other marine mammals. So even researchers who dedicate their lives to studying narwhals say glimpsing these shy creatures is a rare treat.

Surviving Melting Ice

Narwhals depend on Arctic ice for food and shelter. In October, they migrate to Baffin Bay, off the coast of Greenland, where they spend their winters. They dive and hunt fatty fish that live in the ice-covered waters and shield themselves from predators in the Bay that is 95% covered in ice.

But climatologists report that the far north is warming twice as fast as other parts of Earth. Over the last 25 years, Baffin Bay’s perennial ice (ice that remains all year and never melts) shrunk by 9% each decade, according to Science Buzz. This means the ice shrank 9% between 1993 and 2003, then another 9% from 2003 to 2013, and another 9% in the next ten years.

Scientists warn that shrinking sea ice threatens narwhals. For instance, orcas hunt narwhals, but these large killer whales cannot travel through ice-covered waters. Without the protection of ice, narwhals might more often be orca lunch. In addition, melting ice opens paths for large ships to travel through Arctic waters. Noise and pollution from these ships could disturb the narwhal’s habitat by scaring away their fishy food, interrupting narwhal echolocation, and bothering the shy unicorns of the sea. As reported in The New Yorker, a group of researchers tested this theory by strapping a heart-rate monitor and listening device to a narwhal named Nemo. They tracked Nemo as he swam, hunted, and talked to narwhals in his pod. The researchers observed that when noisy ships passed through the Arctic, Nemo fell silent—no vocalizing to communicate or hunt—for 24 hours.

But, narwhals are fighting back against climate change…even if they don’t realize it. Scientists are using these marine mammals to study how fast the Arctic is warming and the impacts of a shifting climate.

Data-Collecting Divers

Studying the impacts of climate change in the Arctic is tricky, mainly because the Arctic is vast and remote. Measuring water temperatures and glacial melting costs scientists lots of time and money.

So in 2005, Kristin Laidre, a marine ecologist, had an idea — let’s use narwhals deep-sea diving to help collect data. Laidre and her team attached tags with thermometers to fourteen narwhals. The tags read water temperatures as narwhals swam under the ice. Laidre used narwhals to measure temperatures in the Baffin Bay, where narwhals spend their winters.

Later in 2018, she partnered with NASA’s Oceans Melting (hilariously nicknamed Project OMG) to track the impacts of global warming. Narwhal data helps NASA predict glacier melt and rising sea levels more accurately.

Tusks that Talk

Narwhal tusks are also teaching scientists about the impacts of climate change. Narwhals live up to 50 years, and their tusks grow as they age. Think of their tusks like a tree trunk. Scientists can read the rings of a tree over time to learn about the tree’s environment. Similarly, scientists can read the layers of a narwhal’s tusk to learn about their oceanic world.

According to Wired, an international team of researchers studied the tusks of ten narwhals and uncovered data about the Arctic climate going back to 1962. The tusks showed that narwhals’ diets have changed. Before 1990, narwhals ate prey like Arctic cod and halibut in oceans covered in thick sea ice. But in the last 20 years, tusks showed that narwhals shifted to eating fish from open waters (water with only small amounts of sea ice). Scientists hypothesize that this dietary shift is a result of climate change. As the ice melts, cod and halibut populations decline, or these fish move farther north to colder waters.

Either way, this change in the kinds of fish narwhals eat means fewer calories for the narwhal. Arctic cod and halibut are fatty fish. Less cod and halibut, fewer blubbery pounds for the narwhal. As a result, climate change could impact their energy and ability to survive in the frigid Arctic.

Scientists are still exploring theories about why narwhals’ diets are changing. But, one thing is for sure, using narwhal tusks to study climate holds promise. By examining one tusk, scientists can unlock decades of data. And there is potential to look even further back than 1962. Natural history museums around the world have narwhal tusks, some that are more than 100 years old. Think of all the stories these tusks can tell about the Arctic waters.