Changing Planet

Bears and Ice

By Paul Greenberg, Safina Center Fellow

The money shot of climate change is without doubt that of a polar bear stranded on a tiny island of ice, seemingly hopelessly adrift while the world around melts into oblivion. But as we pulled into an anchorage off Spitsbergen Island in the territory known as Svalbard this weekend, I came to understand that this iconic image tells a very different story about the way bears live. In fact, if everything is going right with climate and bear habitat, polar bears want to be floating on ice. Fast ice, that is ice that fringes the edge of dry land on one side and more permanent sea ice on the other is prime hunting ground of the polar bear. It’s very movement and permeability is a way for this energy-intensive animal to conserve its fuel while searching for its next meal.

That next meal is, more often than not, a seal, a ringed seal perhaps or a harp or a bearded. Seals spend about 80% of their lives in the water. That 20% of the time on land is when they are most vulnerable to bears. Bears know this very well. They also know that seals will need to exit their preferred element to breath from time to time. So a bear will sit, sometimes for hours near the exit hole on fast ice, waiting for a blubbery seal to emerge and take what the polar bear hopes will be its last breath. For a polar bear, a seal is about food and water–bears rarely have access to freshwater and so the liquid contained in seal blubber hydrates them at the same time that it nourishes. For this reason bears usually leave the meat on a seal to the birds.

The seal-on-ice hunting strategy can be pretty successful but once a seal has been eaten or spooked from its hole, the bear has to move on to a new one. That’s where the ice becomes essential. Every new sheet of ice is new territory when it comes to hunting for a new seal breathing hole spot. Polar bears’ extra wide feet allows these massive animals to spread their weight out, allowing them to pad around on thin, as well as thick, ice. In this way, the floating ice archipelago of the Arctic Sea brings bears and prey inexorably together, a flow of energy from animal to animal every bit as cyclical as the tides and the winds.

Svalbard is one of the polar beariest places in the world, home to about 3,000 animals altogether (there are an estimated 25,000 polar bears total, worldwide). And so it was no surprise that we sighted one right away. “Bear,” one of the passengers said nonchalantly, peering through the lens of his long-range Nikon. Soon radios were abuzz and a ring of Zodiacs formed around the roaming animal. Leisurely, the roughly 400-pound female (or perhaps juvenile male) loped around the edge of the ice that extended like a shelf into the bay. I managed to snap a quick picture with my iPhone camera:

Photo: Paul Greenberg

Fortunately Cian Ryan, an amateur wildlife photographer was aboard my Zodiac with a serious lens, affording a closer look.

Photo: Cian Ryan

Later we could see another bear’s tracks, as large as two human hands hugging the shore, looking for a passageway across the bay.

Photo: Paul Greenberg

May is a precious make-or-break month for polar bears. It is when mothers must either hunt for their cubs or double their body weight so that they can bring a fetus to term. Fast ice lets this happen but that fast ice diminishes as each week passes, as the summer sun grows more intense. By August the ice has melted away, and the chance of snaring a seal are minimal. By the time the tundra is blooming with Arctic flowers and all other creatures celebrate life’s summertime bonanza, polar bears on Svalbard will hunker down in the muck and wait. Aside from the occasional egg stolen from a bird’s nest here and there, they are slowly starving, stuck by summertime weather when the mass transit system of ice goes on strike. It’s a tricky time for bears. If they time it wrong they will burn through their fat reserves, and by October they will be too tired to hunt when the ice finally forms again….

Which is why the vanishing ice of the Arctic is so concerning.

Assembled from NASA Earth Observatory images by Jesse Allen, using data from the Advanced Microwave Scanning Radiometer 2 AMSR-2 sensor on the Global Change Observation Mission 1st-Water (GCOM-W1) satellite. (Wikimedia Commons)

In the graphic above, note that the biggest loss of ice isn’t the more central thick ice at the poles but the fast-moving sea ice on its fringes. Thicker, older ice is of little use to seals and bears. That kind of ice doesn’t afford breathing holes for seals nor hunting grounds for their principle predators. That this collapse of habitat should come now is particularly heartbreaking. Polar bears are in fact in the middle of a major resurgence. For most of the 20th century they were hunted hard by trappers using “kill boxes” in which a piece of seal meat was affixed to a string which in turn was tethered to a hidden gun’s trigger; a trap that in effect tricked bears into shooting themselves. Today the kill boxes are gone. Bears are now much better protected in Svalbard and much of the Arctic. In fact, because both trapping and traditional Inuit hunting have declined markedly there are probably more polar bears alive today than in any time since Homo sapiens took up residence in the Arctic. But should we lose that sea ice, that “edge” that gives polar bears their edge, the high numbers of bears could collapse quite quickly, possibly by the middle of this century.

That’s life in the Arctic. Gaming a system with very thin profit margins of energy. Margins negotiated by that all-important broker of climate: ice.

Ecologist Carl Safina is author of seven books, including the best-selling “Beyond Words; What Animals Think and Feel,” and “Song for the Blue Ocean,” which was a New York Times Notable Book of the Year. His writing has won a MacArthur “genius” prize; Pew and Guggenheim Fellowships; book awards from Lannan, Orion, and the National Academies; and the John Burroughs, James Beard, and George Rabb medals. His work has been featured in The New York Times, The Los Angeles Times, The Washington Post, National Geographic, CNN.com and elsewhere, and he hosted the 10-part “Saving the Ocean” on PBS. Safina is founding president of The Safina Center at Stony Brook University.

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