Anchorage AL (SPX) Dec 17, 2010
Sea-ice habitats essential to polar bears would likely respond positively should more curbs be placed on global greenhouse gas emissions, according to a new modeling study published in the journal, Nature.
The study, led by the U.S. Geological Survey, included university and other federal agency scientists. The research broke new ground in the "tipping point" debate in the scientific community by providing evidence that during this century there does not seem to be a tipping point at which sea-ice loss would become irreversible.
The report does not affect the decision made by the U.S. Fish and Wildlife Service in 2008 to list the polar bear as a threatened species.
This new study builds and expands upon studies published by the USGS in 2007. The new study evaluates additional scenarios in which greenhouse gas emissions are reduced in comparison to the business-as-usual scenario that was exclusively used in the previous research.
Modeling outcomes for the additional scenarios provided evidence that the projected continuation of Arctic sea-ice decline could be altered if greenhouse gas emissions were mitigated in a manner that stabilizes atmospheric CO2 levels at or less than around 450 parts per million. Current CO2 levels are around 390 ppm.
The 2007 studies by the USGS had projected that under the business-as-usual greenhouse gas emissions scenario, future reduction of Arctic sea ice could result in a loss of two-thirds of the world's polar bear population by mid-century.
They had also shown that under this scenario, loss of sea ice would have such a drastic negative effect on polar bears that other efforts to reduce stress on their populations would have negligible benefits.
Other stress factors considered in the modeling include disease and predation, overutilization, contaminants, tourism, bear-human interactions, oil and gas activity, and shipping. The earlier study did not examine other greenhouse gas emission scenarios.
The new analyses published in the journal, Nature, indicate that with lower greenhouse gas emissions, coupled with reductions in other population stressors, polar bears could persist in all four ecoregions where they presently occur, said Steve Amstrup, lead author of the study and a scientist emeritus with the USGS Alaska Science Center.
Amstrup noted that their new work emulated the rapid sea-ice loss that occurred in the Arctic between September 2006 and September 2007 when the loss of sea ice equaled the total amount of ice lost during the previous 27 years. This exponential loss of ice during such a short time was one of the reasons why so many scientists were concerned that there might be a tipping point beyond which sea ice would be irreversibly lost.
"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."
Polar bears depend on sea ice as a platform to hunt seals, their primary food. Current declines in habitat have been associated with declines in body stature, survival rates, and population size in broad areas of the current polar bear range.
Share This Article With Planet Earth
United States Geological Survey
Beyond the Ice Age
Santa Cruz CA (SPX) Dec 15, 2010
Deep sediment cores retrieved from the Bering Sea floor indicate that the region was ice-free all year and biological productivity was high during the last major warm period in Earth's climate history. Christina Ravelo, professor of ocean sciences at the University of California, Santa Cruz, will present the new findings in a talk on December 13 at the fall meeting of the American Geophysi ... read more
Caricom-Australia chide empty promises to Haiti|
Tearful homecoming for Pakistan flood survivors
Clinton attacks slow Haiti quake progress
Clinton Haiti meeting moved due to unrest
Physicist Developing And Improving Designer optical Materials
Japan's Sharp to build LCD lines for smartphones: report
Endeavor Power Launches Endeavor Metals
Apple to open Mac App Store on January 6
A Positive Step In The Face of Uncertainty
Warm water may be hurting cod food supply
EU reduces fishing quotas to save cod
US water has large amounts of likely carcinogen: study
Arctic Sea Ice Greenhouse Gases And Polar Bear Habitat
Bering Sea Was Ice-Free And Full Of Life During Last Warm Period
Arctic icecap safe from runaway melting: study
Russia plans annual arctic conferences
Australians buy cows and sheep with a mouse
Goji Berries Have A Significant Placebo Effect
German giants Bayer, BASF team up on GM rice
McDonald's to speed up China expansion
Volcano in Guatemala rumbling
Colombia faces rising death toll in floods
EU clears aid for flood-ravaged eastern Europe
New Way Found Of Monitoring Volcanic Ash Cloud
China not opposed to Sudan leader's arrest: WikiLeaks
Frontline Ivory Coast town fears new civil war
Interim leader urges army must back new Guinea president
Gambia denies it was intended recipient of Iran arms
Researchers Discover Compound With Potent Effects On Biological Clock
Our Flawed Understanding of Risk Helps Drive Financial Market Instability
Woman who knows no fear could offer brain clues
Early Settlers Rapidly Transformed New Zealand Forests With Fire
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2010 - SpaceDaily. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement|