Climate Change
One Scientist's View
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Polar bears are seen by many to be the arctic version of the "canary in the mine shaft" — an early-warning system of the types of changes we may see in the future, if the climate-change trajectory we've seen over the past 25 years continues.
That "if" —in the opinion of Dr. Steven C. Amstrup of the USGS Alaska Science Center — is critical to include when discussing climate change and its effect on polar bears. "IF the trajectory we've seen over the last 25 years continues, and IF that trend accelerates as suggested by some climate modelers, then yes, in a hundred years the sea ice may have disappeared from much of the currently occupied polar bear habitat. But the final answers are not in, for any of the analyses of any of the polar bear populations."
Amstrup believes there are inherent dangers in looking at past events and trying to draw too many conclusions — especially because we don't know how the current climate cycle will end. Arctic regions experienced warming trends in the early part of the 1900s, for example, and subsequently cooled back down. But many scientists and climate modelers say this time could be different. "The concern now is that the current warming may reflect a natural cycle that is being exacerbated by the influence of greenhouse gases," Amstrup says.
He continues, "Many climate scientists believe the increased levels of CO2 and other greenhouse gases released into the atmosphere by humans may overwhelm the cooling tendencies of natural temperature cycles, and result in a continuing warming trajectory. If those scientists are correct, serious problems could result. Polar bears may show problems first. If the trend were to continue unabated, much of life on earth — as well as critical systems such as water, mineral, and nutrient cycles — also would be altered. The ‘IF', of course, is that we know how earlier cycles ended; we don't know for sure what our current cycle may bring."
That "if" —in the opinion of Dr. Steven C. Amstrup of the USGS Alaska Science Center — is critical to include when discussing climate change and its effect on polar bears. "IF the trajectory we've seen over the last 25 years continues, and IF that trend accelerates as suggested by some climate modelers, then yes, in a hundred years the sea ice may have disappeared from much of the currently occupied polar bear habitat. But the final answers are not in, for any of the analyses of any of the polar bear populations."
Amstrup believes there are inherent dangers in looking at past events and trying to draw too many conclusions — especially because we don't know how the current climate cycle will end. Arctic regions experienced warming trends in the early part of the 1900s, for example, and subsequently cooled back down. But many scientists and climate modelers say this time could be different. "The concern now is that the current warming may reflect a natural cycle that is being exacerbated by the influence of greenhouse gases," Amstrup says.
He continues, "Many climate scientists believe the increased levels of CO2 and other greenhouse gases released into the atmosphere by humans may overwhelm the cooling tendencies of natural temperature cycles, and result in a continuing warming trajectory. If those scientists are correct, serious problems could result. Polar bears may show problems first. If the trend were to continue unabated, much of life on earth — as well as critical systems such as water, mineral, and nutrient cycles — also would be altered. The ‘IF', of course, is that we know how earlier cycles ended; we don't know for sure what our current cycle may bring."