9/12/2011 7:20:17 PM
Sea Ice Losses & Polar Bear Encounters (Press Release)
Arctic sea ice coverage reached historic lows in August, a harbinger of what is to come unless action is taken to reduce greenhouse gas emissions.
(Bozeman, MT, September 12, 2011) - Arctic sea ice coverage declined to a record low this August, with the sea ice extent fifty percent lower than it was just forty years ago, according to a new report by the University of Bremen. It was also a summer with an increased number of unusual and tragic polar bear-human encounters, including a fatal bear attack on a teenage camper in Svalbard and a polar bear shot to death in an Alaskan oil field.
Dr. Steven C. Amstrup, chief scientist for Polar Bears International, the world's leading polar bear conservation group, says the rapid and prolonged ice retreat in the summer months is bad news for polar bears, which depend on the sea ice to catch their prey. Scientists have long predicted that nutritionally stressed bears ranging more widely in search of prey will lead to an increase in conflicts between polar bears and humans.
"More prolonged ice absence means more polar bears will starve, with older bears and the very young the most vulnerable," he says. "Food-stressed bears are more likely to expand their ranges looking for food, and more likely to encounter humans. While we don't know all the factors involved in each tragedy this summer, the uptick in human-polar bear encounters is consistent with what we expect when hungry polar bears are driven ashore."
Amstrup cautions, however, that as bad as this summer was for sea ice coverage, one bad summer isn't the real problem. The real problem is that without reductions in greenhouse gas emissions the long-term trend in sea ice can only be downward.
The scientist notes that global warming doesn't mean an end to natural weather variations—like this winter's intense warmth in the Arctic or last winter's unusual cold in the Midwest. Such natural variability could lead to some good ice years for polar bears. But as long as concentrations of greenhouse gases rise, the average temperature around which those fluctuations occur will increase. With the average global temperature rising, the average sea ice extent will decline until all years are bad ones for polar bears.
"There's no uncertainty about the physics requiring the world to warm as greenhouse gas concentrations rise," he says. "It's been understood for over a hundred years. The only uncertainty about climate warming concerns the timing of future warming and possible effects. Natural fluctuations in the climate system prevent us from confidently predicting, for example, the first year the mean annual temperature in New York is two degrees warmer than now—or the first summer the Arctic will be ice-free. Crossing both thresholds is assured, however, unless we reduce greenhouse gas emissions."
Amstrup says that the natural chaos in the climate system may overshadow the global warming signal next year or the year after that.
"If we're lucky, we'll have a series of cold years with circulation patterns that conserve sea ice," he says. "Ultimately, however, the greenhouse gas signal will clearly emerge from the noise in the system."
"Without mitigation of the rise of greenhouse gases, the situation for polar bears and many other species can only worsen, and polar bears ultimately will disappear."
Polar Bears International is the world's leading nonprofit organization focused on the conservation of the polar bear and its habitat through research, education, and stewardship. Learn more at www.polarbearsinternational.org and www.facebook.com/polarbearsinternational.
Dr. Steven C. Amstrup
Chief Scientist, Polar Bears International
Photo ©Daniel J. Cox/Natural Exposures.