Think Antarctica and you think snow. A vast and unending, featureless panorama of it.
Andrew McDonnell, a PhD student at the Woods Hole Oceanographic Institution and MIT, traveled to the Palmer U.S. Research Station in Antarctica to see snow, but not on land. Instead Mr. McDonnell was interested in the timeless undersea blizzard of particulate matter known as marine snow, the ghostly detritus of animals that descends the water column, sometimes taking months to reach the bottom.
Palmer Station sits on a drab pile of rocks on the western shore of the Antarctic Peninsula. Here Adelie penguins are disappearing by the tens of thousands (from 35,000 breeding pairs in 1973 to just 5,000 today), 85 per cent of the glaciers are receding and average winter temperatures have jumped 11 degrees Fahrenheit in the past 50 years. In fact, on the miserable, sleeting 35-degree day that Mr. McDonnell gave a talk at the Vineyard Haven Library this week, his sunbathing colleagues at the Palmer Station were enjoying a cloudless 36-degree beauty.
Could there be a connection between these unusual changes on land and the submarine snowflakes Mr. McDonnell was investigating?
Antarctica is an otherworldly place where the summer sun flirts with the horizon without ever quite dipping below, casting strange, oblique rays of twilight gold on the jagged mountains that jut 4,000 feet straight out of the sea. Untouched by human influence for millions of years and protected by the Antarctic Treaty for peaceful scientific research, it is also a pristine laboratory for researchers in the natural sciences.
“Geologists on my research vessel would go to the beach and come back with chests full of fossils,” said Mr. McDonnell. “They would pick up fossils of giant sea snails a meter across which were just lying on the ground because no one had ever been there.”
But Mr. McDonnell came to the Antarctic to study the carbon cycle. The earth’s atmosphere holds roughly 597 gigatons of carbon, but the deep ocean holds 37,200. If the world’s rain forests are a carbon sink, then the world’s deep oceans are a swimming pool.
Phytoplankton in the ocean locks up carbon and other elements by converting them to organic matter through photosynthesis. When these animals die, they sink to the bottom, taking their carbon with them, and in doing so, changing the chemistry of the ocean around them. This is what is known as a biological pump. It is why some people have advocated fertilizing the surface of the earth’s oceans to combat climate change, effectively accelerating the pump by kicking up a northeaster of marine snow.
On Mr. McDonnell’s latest research voyage it was his job to measure how effectively this pump was operating in Antarctica, where seasonal changes in sea ice have disrupted the local ecology. He did this by catching snow as it fell through the frigid depths and measuring it. It turned out that Antarctic waters are not as productive as in years past. The reasons are complicated but depend in part on the disappearance of sea ice, which the local ecosystem depends on, but are also due to ongoing global ocean acidification, which is caused by the sea’s absorption of excess carbon dioxide in the atmosphere. This hinders the development of some ph-sensitive organisms (oceans saturated with carbon dioxide are also able to absorb less carbon, leaving more of it in the atmosphere).
When primary production in the form of plankton slows, animals up the food chain suffer, such as salps, krill and fish; and later; penguins, seals and whales.
Antarctica wasn’t all work for Mr. McDonnell though. He described playing Frisbee golf on a moraine once covered by glaciers, visiting abandoned Chilean research stations and placing bets on which parts of the landscape would disappear by which date. Scientists are not as a whole a particularly optimistic bunch.
Mr. McDonnell gives talks about his research not only to raise awareness of the ecological issues facing Antarctica and the world at large, but to raise awareness of Antarctica itself.
“It’s amazing to me how many people in the general public don’t even know that it really exists,” he said, adding: “I saw this girl from high school who when I told her I was doing research in Antarctica said, ‘Oh, that’s up by like the North Pole, right?’” He laughed: “Well, not exactly.”
Mr. McDonnell, who fell asleep most nights to the violent grinding sound of calving glaciers near Palmer, finally pulled up a slide of the Wilkins Ice Shelf, an area he visited last March.
“We were offshore from Charcot Island here, which was connected to the continent by an ice bridge,” he said. “When we got back to shore, by April Charcot Island was no longer connected to the mainland by this giant ice sheet because the ice shelf had disintegrated.” Wilkins is the tenth major ice shelf to collapse in recent decades.
“For me that was quite a lesson,” Mr. McDonnell said. “In my lifetime and in fact in my one trip to Antarctica the landscape was dramatically changing.”