 |
|
Warming climate may put chill on arctic polar bear population
September 14, 2006Some travel agencies touting Arctic tours have been revving up their recent promotions to tourists about the increased likelihood they will spot polar bears in this region where several populations of polar bears live. According to scientists from NASA and the Canadian Wildlife Service, these increased Arctic polar bear sightings are probably related to retreating sea ice triggered by climate warming and not due to population increases as some may believe.
The new research suggests that progressively earlier breakup of the Arctic sea ice, stimulated by climate warming, shortens the spring hunting season for female polar bears in Western Hudson Bay and is likely responsible for the continuing fall in the average weight of these bears. As females become lighter, their ability to reproduce and the survival of their young decline. Also, as the bears become thinner, they are more likely to push into human settlements for food, giving the impression that the population is increasing. The study will be published this week in the September issue of the Journal Arctic.
Claire Parkinson, a scientist at NASA's Goddard Space Flight Center, Greenbelt, Md., and Ian Stirling, a senior scientist with the Canadian Wildlife Service, Edmonton, Alberta, used NASA satellite observations captured from 1979 to 2004 to show the reduction in sea ice cover in several specific areas where there are known polar bear populations. In most of the areas studied, they found that ice break-up in these areas has been occurring progressively earlier.
"Our research strongly suggests that climate warming is having a significant and negative effect on a primary species reliant on the sea-ice cover for survival," said Parkinson.
The researchers studied the sea ice in regions that are home to five different polar bear populations: western Hudson Bay, eastern Hudson Bay, Foxe Basin, Baffin Bay and Davis Strait-Labrador Sea. "Polar bears live much of their lives on the sea ice, which is fundamental for their survival, at least in terms of their traditional lifestyles," said Parkinson. "It's the sea ice surface that provides them a platform from which to hunt seals and other marine mammals for food."
Sea ice is most scarce during the summer months, causing the bears to retreat to land and fast on their stored fat reserves until sea ice comes back in the fall. "Our concern is that if the length of the sea ice season continues to decrease, then the polar bears will have shorter periods on the ice, when they can feed, and longer periods on the land, during the open-water season in summer and early fall," she said. "Their stored fat from life on the ice will likely not provide enough nourishment for the fasting period on land, posing a clear danger to their health and, in the long term, possibly to their species."
Sea-ice cover in these regions has decreased since at least 1978, the beginning of consistent satellite monitoring. The researchers used 26 years of satellite data using data from NASA's Nimbus 7 satellite and the Defense Meteorological Satellite Program's Special Sensor Microwave Imager.
"By reviewing satellite data, we found that sea-ice cover break-up in western Hudson Bay took place about seven to eight days earlier per decade," said Stirling. "An extra month of fasting resulting from this phenomenon over four decades can significantly impact the polar bears' eating habits and survival."
"One of the most important things that enabled us to do this study was our ability to draw on long-term satellite databases on Arctic ice," said Stirling. "NASA has maintained an extensive and invaluable database of these observations that made it possible for us to combine our different expertise on this study."
In addition to monitoring sea-ice changes, the researchers incorporated data from previous polar bear studies in the same Arctic regions that also indicated the likelihood that progressively earlier break-up of sea ice was likely to cause problems for polar bears.
"In 1980 the average weight of adult females in western Hudson Bay was 650 pounds. Their average weight in 2004 was just 507 pounds - a 143-pound reduction," said Stirling. A 1992 study in the Canadian Journal of Zoology indicated that no females weighing less than 416 pounds gave birth the following spring.
According to Stirling, if the climate continues to warm as projected by the Intergovernmental Panel on Climate Change and the ice continues to break up progressively earlier, it is likely that in 20-30 years polar bear reproduction in western Hudson Bay will be significantly limited. Similar events may eventually happen in other areas included in the study.
NASA/Goddard Space Flight Center
"Our research strongly suggests that climate warming is having a significant and negative effect on a primary species reliant on the sea-ice cover for survival," said Parkinson.
The researchers studied the sea ice in regions that are home to five different polar bear populations: western Hudson Bay, eastern Hudson Bay, Foxe Basin, Baffin Bay and Davis Strait-Labrador Sea. "Polar bears live much of their lives on the sea ice, which is fundamental for their survival, at least in terms of their traditional lifestyles," said Parkinson. "It's the sea ice surface that provides them a platform from which to hunt seals and other marine mammals for food."
Sea ice is most scarce during the summer months, causing the bears to retreat to land and fast on their stored fat reserves until sea ice comes back in the fall. "Our concern is that if the length of the sea ice season continues to decrease, then the polar bears will have shorter periods on the ice, when they can feed, and longer periods on the land, during the open-water season in summer and early fall," she said. "Their stored fat from life on the ice will likely not provide enough nourishment for the fasting period on land, posing a clear danger to their health and, in the long term, possibly to their species."
Sea-ice cover in these regions has decreased since at least 1978, the beginning of consistent satellite monitoring. The researchers used 26 years of satellite data using data from NASA's Nimbus 7 satellite and the Defense Meteorological Satellite Program's Special Sensor Microwave Imager.
"By reviewing satellite data, we found that sea-ice cover break-up in western Hudson Bay took place about seven to eight days earlier per decade," said Stirling. "An extra month of fasting resulting from this phenomenon over four decades can significantly impact the polar bears' eating habits and survival."
"One of the most important things that enabled us to do this study was our ability to draw on long-term satellite databases on Arctic ice," said Stirling. "NASA has maintained an extensive and invaluable database of these observations that made it possible for us to combine our different expertise on this study."
In addition to monitoring sea-ice changes, the researchers incorporated data from previous polar bear studies in the same Arctic regions that also indicated the likelihood that progressively earlier break-up of sea ice was likely to cause problems for polar bears.
"In 1980 the average weight of adult females in western Hudson Bay was 650 pounds. Their average weight in 2004 was just 507 pounds - a 143-pound reduction," said Stirling. A 1992 study in the Canadian Journal of Zoology indicated that no females weighing less than 416 pounds gave birth the following spring.
According to Stirling, if the climate continues to warm as projected by the Intergovernmental Panel on Climate Change and the ice continues to break up progressively earlier, it is likely that in 20-30 years polar bear reproduction in western Hudson Bay will be significantly limited. Similar events may eventually happen in other areas included in the study.
NASA/Goddard Space Flight Center
Polar Bear News and Current Polar Bear Events RSSArctic marine mammals on thin ice
The loss of sea ice due to climate change could spell disaster for polar bears and other Arctic marine mammals. The April Special Issue of Ecological Applications examines such potential effects, puts them in historical context, and describes possible conservation measures to mitigate them.
Arctic climate models playing key role in polar bear decision
The pending federal decision about whether to protect the polar bear as a threatened species is as much about climate science as it is about climate change.
Why are lions not as big as elephants?
Carnivores are some of the widest ranging terrestrial mammals for their size, and this affects their energy intake and needs.
Arctic sea ice declines again in 2006, say University of Colorado researchers
While cool August temperatures prevented sea ice in the Arctic from reaching its lowest summer extent on record, 2006 continued a pattern of sharp annual decreases due to rising temperatures probably caused by greenhouse warming.
Climate scientists spotlight Arctic warming, plight of polar bears
A climate scientist at the University of Chicago and 30 of her colleagues from across North America and Europe are urging the U.S. Fish and Wildlife Service to list the polar bear as a threatened species because global warming is melting its sea-ice habitat.
The species that propagate slowly, become extinct sooner
The animals and plants of our planet are becoming extinct under the pressure of civilization. The scientists have counted that one species vanishes from Earth every hour. The mammoth, passenger pigeon, gare-fowl, Steller`s sea cow - these are the most well-known of extinct species, but hundreds of species are next in turn. Can the scientists forecast what species is the first in this succession and what species is not under the threat of complete extinction? If the answer is known, the effort and funds intended for the preservation of natural resources could be distributed correctly. Leonard Polishchuk, Ph. D. (Biology), research assistant of the Chair of General Ecology, Faculty of Biology,
More Polar Bear News Articles
 | Magic Tree House Boxed Set, Books 9-12: Dolphins at Daybreak, Ghost Town at Sundown, Lions at Lunchtime, and Polar Bears Past Bedtime by Mary Pope Osborne The Magic Tree House adventures continue in books 9—12. Morgan the magical librarian of Camelot challenges Jack and Annie to discover the answers to four riddles as they travel under the sea to the Wild West, the African plains, and the frozen Arctic. If they succeed, they will become Master Librarians! Books in this set include:Dolphins at Daybreak (#9)Ghost Town at Sundown (#10) Lions at... |
 | Polar Bear, Polar Bear, What Do You Hear? by Bill Martin Jr. This hardcover childrens book is beautifully written/boldly illustrated by Eric Carle, Bill Martin Jr, and Henry Green. Zoo animals, like polar bears and walruses make their accompanying sounds for each other and children imitate the sounds for the... |
 | God Gave Us You by Lisa Tawn Bergren When a charming polar bear cub climbs into bed one night, she asks her Mama a very important question--one that little "human cubs" often wonder about, too: "Where did I come from?"As Mama bear tucks her youngest cub under the quilts, she gently, tenderly, and reassuringly communicates the message loving parents everywhere (bears and non-bears alike) want their little ones to hear: "We wanted... |
 | The Three Snow Bears Aloo-ki glances up from fishing and sees her sled dogs floating off on an ice floe. She races after them and comes upon an igloo. Being a curious girl, she goes inside only to find no one home. That’s because the polar bear family who lives there is out walking while their breakfast cools off. Aloo-ki eats some soup, tries on their boots, and finally crawls into the smallest bed for a nap.... |
 | A Boy and a Bear: The Children's Relaxation Book by Lori Lite A Boy and a Bear teaches young children how to relax and calm themselves. Written for children 3 - 10 years old, this book tells the story of a young boy who encounters a polar bear while they are both climbing a snow covered mountain. The boy and bear become friends and learn an important lesson in relaxation together. As the bear watches the boy breathing, children mirror their movements... |
 | God Gave Us Heaven by Lisa T. Bergren As the sun rises on her snow-covered world, Little Cub wonders aloud…“What is heaven like?”With tender words, her Papa describes a wonderful place, free of sadness and tears, where God warmly welcomes his loved ones after their life on earth is over. Little Cub and Papa spend the day wandering their beautiful, invigorating arctic world while she asks all about God’s home:... |
 | Polar Bears Past Bedtime (Magic Tree House, No. 12) by Mary Pope Osborne The Magic Tree House transportss Jack and Annie to the freezing Arctic. There, they must solve the final riddle to become master librarians. But it's not going to be easy--especially when they have cracking ice, a seal hunter, and a prodigious polar bear to deal with. Will they be able to solve the riddle before they get iced... |
 | Raising The Past by Jeremy Robinson FROM THE ICE. . . A mammoth, flash frozen in solid ice 10,000 years ago is brought to the surface by a team of scientists. An act of sabotage frees the giant from its icy tomb and reveals the secret held inside. OUT OF THE MAMMOTH. . . The body of an ancient woman, cloaked in furs, slides out of the mammoth's belly. But it is not the woman that holds the team's attention...it is the... |
 | God Gave Us Two by Lisa Tawn Bergren, Laura J. Bryant Now that Mama polar bear has another baby in her tummy, Little Cub is bursting with curiosity. “Why do we need a new baby?” she asks. “If we don’t like the new baby, can we send it back?” “Will you forget me when the new baby comes?”Gently and lovingly, Mama and Papa assure their firstborn that the new baby is a gift from God they want very much, just as... |
 | How One Little Polar Bear Captivated The World (Knut) by Craig Hatkoff, Juliana Hatkoff, Isabella Hatkoff, Dr. Gerald R. Uhlich When Knut was born, the first polar bear cub at the Berlin Zoo in more than thirty years, he was no bigger than a snowball and unable to care for himself. His mother, a rescued East German circus bear, didn't know how to take care of Knut and rejected him. Knut would have died if it weren't for Thomas Dorflein, a zookeeper who nurtured Knut, feeding him, sleeping with him, and giving him the love... |
| © 2008 BrightSurf.com |