Polar bear. Photo credit: wikimedia commons
Two-thirds of the world's polar bears could disappear within 50 years due to greenhouse-gas emissions, said a 2007 report by the U.S. Geological Survey. The bears need Arctic sea ice in order to hunt the seals and other offshore prey that sustain them. But our warming climate is rapidly melting the vital sea ice. Between 1979 and 2010, Arctic sea ice cover decreased by an average of 11.5% per decade. Due to loss of ice, many bears are starving to death already. The polar bear, Ursus maritimus, is now officially listed as "threatened."
A team of scientists stationed in Alaska may have some tentative good news, though. They just published a new assessment of polar bears' future in the Dec 16 (2010) edition of the journal Nature. Steven Amstrup, senior scientist with "Polar Bears International," and his team reported five possible scenarios for greenhouse-gas emissions and ice melting this century. The researchers concluded that Arctic sea ice may not necessarily reach a catastrophic "tipping point" that would lead to an inevitable disintegration of all the ice. The future of the bears' ice depends on how much we can limit greenhouse-gas emissions in the years to come and how much we can stabilize the climate. One factor in the bears' favor is that thinner ice (as it diminishes) becomes more responsive to the cold water below it and can more easily regrow in winter.
Amstrup's team used climate modeling to predict "sea ice habitability" for the bears over the coming decades, an index that includes the amount of ice over the shallow waters (continental shelves) where seals and other prey hang out, the number of months per year those waters are covered with ice, and the distance between that ice and the more northerly pack ice where polar bears also hunt (there's a limit to how far polar bears can swim from one ice mass to another).
Polar bear swimming from one pack of ice to another. Photo credit: wikimedia commons
Says Amstrup, “There’s a widely held perception that nothing can be done to help polar bears and the arctic ecosystem. Our findings show this isn’t true. Our findings offer a message of hope but they also underscore the urgent need for reductions in greenhouse gas emissions. ”
For more information about Amstrup's study and a 2-minute video message from the bear researcher, go to this page on "Polar Bears International." Or check it out on youtube, called "Hope for Polar Bears" by Steven Amstrup.
Keywords: polar bears Steven Amstrup Polar Bears International bear conservation climate change greenhouse gas emissions global warming Arctic sea ice
Our books on this topic:Veggie Revolution: Smart Choices for a Healthy Body and a Healthy Planet. 2005. Sally and Sadie Kneidel. Fulcrum Books.
Going Green: A Wise Consumer's Guide to a Shrinking Planet. 2008. Sally and Sadie Kneidel. Fulcrum Books.
Some of my previous posts about how you can reduce greenhouse gas emissions:
Livestock produce 51% of annual worldwide gas emissions
New study: meat impacts climate more than buying local
Less meat....smaller footprint
Is local food the greenest choice? New study says no
Earth Day: 3 things you can do