DR. BIANCA PERREN ’93 KNEW a little something about “remote work” long before the pandemic.
As a Quaternary paleoecologist for the famed British Antarctic Survey, Perren’s fieldwork routinely involves visiting some of the most inhospitable locations on earth. Her last trip to the Southern Ocean left her ears throbbing from the constant pounding of gale-force winds. It was supposedly summer in the hemisphere, but it didn’t feel like it.
The winds aren’t exactly pleasant, though they are integral to Perren’s research. In particular, she has been studying the westerlies, the prevailing winds from left to right on a map, which have been making an alarming march southward in recent decades. Perren is trying to understand whether their behavior is a cyclical phenomenon or something more recent, resulting from a kind of stratospheric depletion: the ozone hole.
“We haven’t really known what the natural behavior of the westerly winds is like outside of this ozone period,” Perren says. “What should they be doing normally? And what can we anticipate in the decades to come?”
Quaternary, by the way, refers to the most recent period in the geologic time scale up to our present day. It historically encompasses two epochs, the Pleistocene (from roughly 2.5 million years ago until about 11,000 years ago) and the Holocene. Recently, however, scientists have proposed that we’ve already transitioned into a new age, the Anthropocene, with humans being the central cause of this epochal inflection point.
Perren, whose work appeared in Al Gore’s documentary, An Inconvenient Sequel, has helped advance this thinking. In fact, she and her team recently published a record of the 700-year of history of the winds from sub-Antarctic Marion Island and confirmed that their strength and latitude are indeed linked closely to temperature—and over a much shorter timescale than climate modelers had previously thought.What’s the big deal? The winds drive warmer water to Antarctica, breaking up ice shelves and pulling carbon dioxide and heat out of the atmosphere. They also have an impact closer to home.
“In the last decade or so, we’ve seen incredible drought in South Africa, as well as wildfires in southern Australia and Patagonia,” Perren says. “As you move the winds further south, they stop these major storm systems from delivering precipitation to all these regions.”
Perren establishes ecological records through a process called lake coring, or drilling holes into the muddy bottom of lakes and retrieving samples from below the surface. What might look like a blackish filth stew is filled with sediment that, over time, can stratigraphically form a record of environmental changes. Some cores stretch back tens of thousands of years.
Under a microscope, Perren examines the sediment for diatoms, or unicellular algae. Certain diatoms have a strong affinity for salty environments, and if enough are present in a sample, researchers can make the connection that the westerlies blew salt onto the lakes during that time period.
Perren is currently examining samples from cores she gathered from the southernmost lake in the Americas, on a peninsula jutting out into the Drake Passage.
“These are pretty interesting places on the planet,” says Perren. “On the island near Cape Horn, the last person working here doing any real research there was part of the Beagle expedition [which included Charles Darwin]. They’re really out of the way, so you find really interesting things.”
Getting to these locations isn’t exactly easy. Getting out can be even trickier.
Perren recalled one particularly harrowing helicopter ride off Marion Island in the middle of a dangerous windstorm.
“The pilot said, ‘There’s a shear zone between the water and the air that has less wind so I’m going to cruise that,’” Perren says. “We were probably 2 meters above the sea surface. It was scary.” She adds, “I think most of my family thinks I’m pretty crazy.”
Nonetheless, Perren is planning her next trip to northern Greenland, where she can continue coring lakes in the Northern Hemisphere to gather an environmental record in relation to human migration. In addition to her research, Perren leads tours of the Arctic as an expedition educator for the Students on Ice Foundation.
Since she first visited the Arctic in 1998, she has witnessed dramatic changes. Understanding the driving forces behind them are what compels her to keep revisiting these harsh and forbidding landscapes.
“I worked on a lake during my Ph.D., a little island of rock surrounded by a sea of ice in the Greenland Ice Sheet,” Perren says. “Then I flew over two years ago, and it’s now just part of the land. There’s no ice around it anymore.”
—Zach Schonbrun ’05