Elephant seals in funny-looking hats are helping NASA study climate science.
Outfitted with specialized sensors that resemble lumpy metal yarmulkes with antennae, these pinnipeds are collecting data that’s helping researchers track how heat moves through ocean currents. In a paper published this week in Nature Geosciences, a team of climate scientists led by Caltech oceanographer Lia Siegelman used this clever technique to track changes in temperature as the seal swam the icy waters of the Antarctic.
With the help of one particularly intrepid female seal, the researchers discovered that heat stored at the ocean’s depths can sometimes get swirled back up to the surface thanks to some deeply penetrating currents. While researchers have known that these currents can ferry heat downward into the ocean’s interior, the new findings suggest the reverse is true as well—driving a process that can warm the sea’s topmost layers as well.
That might sound inconsequential, but Siegelman thinks it’s important to incorporate this new information into existing climate models. Oceans serve as a sink for the atmosphere’s heat, which means the cooler their surfaces are, the more energy they can absorb. But with heat rising up from below, the world’s waters might be less equipped to offset rising temperatures than scientists once thought, explains Siegelman in a statement.
What this means in the long term is unclear. As Sarah Zielinski reported for Smithsonian.com in 2014, climate change is reshuffling how ocean waters in the Antarctic move and mix. And what happens in the Antarctic doesn’t stay in the Antarctic: Shifts in the water cycle at our planet’s south pole have reverberating effects on climate and weather throughout the rest of the globe.
Before seals entered the picture, scientists had a pretty limited view of what went on beneath the surface of the Southern Ocean. Here, temperatures can plunge below 30 degrees Fahrenheit, and thick sheets of sea ice block instruments from collecting data. All in all, it’s a pretty unappealing locale for underwater field work.
But none of that troubles southern elephant seals, which spend nine to ten months of each year at sea, swimming thousands of miles and diving up to half a mile beneath the ocean surface—usually about 80 times a day. “Even when they sleep, they dive,” Siegelman said in a separate statement earlier this year. “They float down like a leaf," Siegelman said.”
To capitalize on the seals’ wanderlust, Siegelman and her colleagues tagged a female elephant seal on the Kerguelen Islands, gluing a sensor to her head. (Don’t be alarmed: The researchers remove the tags on the seals’ next visit ashore. Barring that, they’re sloughed off with dead skin during molting season.) With the high-tech hat atop her head, the seal embarked on her post-breeding swim in October of 2014. For the next three months, the researchers followed her 3,000-mile journey, during which she dived 6,333 times, reports Meghan Bartels for Space.com.
Combined with satellite images, the wealth of data the seal recovered gave Siegelman and her team a clearer picture than they’d ever been afforded before. It’s probably safe to say that the significance of this was lost on the seal.
But from the human perspective, it’s clear seals are filling in some massive gaps in knowledge, Guy Williams, a polar oceanographer at the University of Tasmania who’s conducting his own temperature studies with pinnipeds, told Genelle Weule at the Australian Broadcasting Corporation in 2016. “The [seals] have gone to areas where we've never had an observation before.”