No Tipping Points in Polar Bears' Future
Much has been made about the possibility of tipping points in Earth’s environment; points of change which will not allow for any turning back no matter the effort put in. One of the most hyped of these was the Arctic and the possibility of a total loss of ice during summer.
A new study led by the US Geological Survey and the University of Washington has found that not only are tipping points in the Arctic nowhere to be found in their computer models, but that if humans reduce greenhouse gas emissions enough in the next decade or two the Arctic will hold on to enough ice during late summer and early autumn for the native polar bears to survive.
“What we projected in 2007 was based solely on the business-as-usual greenhouse gas scenario,” said Steven Amstrup, an emeritus researcher with the U.S. Geological Survey and the senior scientist with the Montana-based conservation organization Polar Bears International. “That was a pretty dire outlook, but it didn’t consider the possibility of greenhouse gas mitigation.”
The study in question posed that about one-third of the world’s 22,000 polar bears might be left by mid-century and that eventually they could all disappear. This was based on a loss of habitat, mainly the ice, and the inability for the mammals to reach fishing grounds and return safely home before they drowned.
However the new research just published in the December 16 issue of the journal Nature shows that there is no tipping point that would result in an unstoppable loss of summer sea ice.
“Our research offers a very promising, hopeful message, but it’s also an incentive for mitigating greenhouse emissions,” said Cecilia Bitz, a University of Washington associate professor of atmospheric sciences
“Our current research provides strong evidence that it’s not too late to save polar bears from extinction,” said DeWeaver, an atmospheric scientist with the National Science Foundation and co-author of the paper. “We looked for Arctic sea ice tipping points in a climate model in which sea ice is known to be very sensitive to global warming, and we didn’t find any.”
“Instead, we found that the relationship between the loss of sea ice and the average global temperature is linear,” said Amstrup. “In fact, the models indicate that major losses of summer sea ice can occur without pushing ice into a tipping point with permanent ice-free summers. If such a tipping point had existed, it would have meant that efforts to reduce greenhouse gases would have had little value in stemming the loss of polar ice critical for polar bears.”
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