Polar Bear and Seal Decline in the Arctic, Ice-Free Arctic, and Global Warming:
"The results in climate models that include obseved changes in the atmosphere's greenhouse gases and aerosals (atmospheric particles) have been compared with identical calculation where anthropogenic [human developments of] greenhouse gases and aerosals were left out. Recent published results show that human-induced changes correspond with those that have been observed in the ice cover. Statistical analysis in the change of sea ice over the last 40 years compared with changes in a reference analysis over the last 5,000 years gave a 99.9% probability that the changes were human induced. Total area of sea ice in the Arctic in the winters from 1978-1998 shows a shrinking of 610,000 kilometers squared (14% in the 20 years).
Compared to the global mean temperatures over the last hundred years, the temperature of the atmosphere has increased by 0.2 degress Celcius every ten years over the last few decades....The melting of sea ice in the Arctic will probably reduce the submersion of water in the northern regions since the surface layer will be able to be fresher and lighter, and thereby be more difficult to submerse. But at the same time, less ice in the Arctic Ocean will possibly lead to a difference in vertical mixing here than what has been observed until now, resulting in an increase in strength of current flowing out of the Arctic Ocean."
Source: "Towards an Ice-Free Arctic," by L.H.Smedsrud and T.Furvik, Cicerone,2/2000
http://www.cicero.uio.no/cicerone/00/2/en/smedsrud.pdf
"Arctic ice thickness has diminished by 40% over the last 40 years....If the recent rate of thinning is substained, the Arctic Ocean could be ice-free in summer by 2050....The average annual temperature at Resolute has increase by about 1.3 degrees Celcius over the last three decades, an increase of about 2.5% per decade."
Source: "Sea Ice in the Canadian Arctic in the 21st Century," by John C. Falkingham, et. al., Canadian Ice Service, Environment Canada.
http://www.socc.uwaterloo.ca/summer/volume_1/II12_Falkinghametal/II12_Falkinghametal.PDF
"A cascade of impacts, beginning with reduced sea level ice will be manifested in reduced adipost stores [animal fat] leading to lowered reproduction rates because females will have less fat to invest in cubs during the winter fast. Non-pregnant bears may have to fast on land or offshore on the remaining multiyear ice through progressivelly longer periods of open water while they await freeze-up and return to hunting seals. As sea ice thins, and becomes more fractured and libile, it is likely to move more in response to winds and currents so that polar bears will have to walk or swim more and thus use greater amounts of energy to remain contact with the remaining preferred habitats....Given the rapid change of ecological pace in the Arctic, the long generation time, and the highly specialized adaption of polar bears, it is unlikely that polar bears will survive as a species if the sea ice disappears completely as has been predicted." Source: "Polar Bears in Warming Climates," by Andrew E. Derocher et. al, Integr. Comp. Biology, vol. 44, 2004, pp. 163-176.
"Through the 50's, and particularly during the 60's, the was a rapid rise in the polar bears killed....The last estimate of population size indicates that the present population might not be sustainable....Density of ringed seals, where multi-year pack ice prevails are also lower. It seems likely that the lower density of seals reflects the lower overall productivity in the marine ecosystem....
[Reference to Global Warming effecting suitable locations for female maternity dens]
Extensive searching along the Alaskan coast resulted in very few additional maternity dens....In years when pack ice does not reach the coast till later in the winter, female polar bears may not be able to reach the coast or offshore islands and could be forced to den on drifting packs of ice instead.
Beginning in 1989, there was a major shift in the Arctic Oscillation Index...and a record minimum ice extent. More open pack and less multi-year ice in the southern Beaufort Sea both lead to greater melting and thinning of the annual ice, resulting in more open water since 1989. In addition, man annual temperature in April, May, and June have increased steadily and, as a result...the annual ice along the mainland coast during the winter, fresh water melts from rivers and sea ice melts extends farther North into the Beaufort sea than was the case in earlier decades. Melling (1998) has shown that between 1989 and 1996 the upper halocine in the Canada Basin has warmed 0.15 degrees Celcius, an amount sufficient to account for 0.7 meters of sea ice."
Source: "Polar Bears and Seals in the Eastern Beaufort Sea and Amundseb Gulf: A Synthesis of Population Trends and Ecological Relationships over Three Decades," by Ian Stirling, Arctic, vol. 55, 2002, pp. 59-76.
"The presence of sea ice in Hudson Bay and other coastal areas is a major factor affecting interactions between the marine and terrestrial ecosystems. Loss of ice and therefore hunting of seals by polar bears will reduce bear and arctic fox populations within the region. In turn, this is likely to have significant effects on their herbivorous prey populations and forage plants. Further, the undersurface of sea ice is a major site for the growth of algae and marine invertebrates which in turn act as food for the marine food web. A rise in sea-level may flood coastal saltmarsh communities leading to changes in plant assemblages and a decline in foraging by geese and other consumers. The anomalous cooling in the eastern Arctic, primarily in late winter and early spring, has interrupted northern migration of breeding populations of geese and ducks and led to increased damage to vegetation in southern arctic saltmarshes as a result of foraging. It is likely that there has been a significant loss of invertebrates in those areas where the vegetation has been destroyed. Warming will have major effects on permafrost distribution and on ground-ice resulting in a major destabilization of slopes and slumping of soil, and disruption of tundra plant communities. Disruption of peat and moss surfaces lead to loss of insulation, an increase in active-layer depth and changes in drainage and plant assemblages. Increases of UV-B radiation will strongly affect vulnerable populations of both plants and animals. The indigenous peoples will face major changes in life style, edibility of food and health standards, if there is a significant warming trend." Source: "Atmospheric Change and Biodiversity in the Arctic," by Roger I. C. Hansell, et. al., Environmental Monitoring, Vol. 49:2-3, 1998, pp.303-325
"Climatic warming, the first impacts on polar bears (Ursus maritimus ) will be felt at the southern limits of their distribution, such as in James and Hudson bays, where the whole population is already forced to fast for approximately four months when the sea ice melts during the summer. Prolonging the ice-free period will increase nutritional stress on this population until they are no longer able to store enough fat to survive the ice-free period. Early signs of impact include declining body condition, lowered reproductive rates, reduced survival of cubs, and an increase in polar bear-human interactions. These changes are currently detectable in the polar bears of western Hudson Bay." Source: "Possible impacts of climatic warming on polar bears," by Stirling, I and A. E. Derocher, Arctic. Vol. 46, no. 3, pp. 240-245. 1993.
Decrease in Body Mass of Polar Bears in the Hudson Bay Area:
"Estimated body mass values between the periods, calculated using equations showed that the EBM for polar bears captured in 2000–03 was significantly less (7–18% less) than that for bears captured in the mid-1980s....This finding has direct implications for ongoing research on polar bears in southern Hudson Bay, where long-term monitoring of body condition has become a high priority amid growing concern that climatic warming may cause a gradual decline in the body condition of polar bears inhabiting Hudson Bay."
Source: "To weigh or not to weigh: conditions for the estimation of body mass by morphometry," by Marc R.L. Cattet and M.E. Obbardb, Ursus, Vol.16:1, 2005, pp102–7
http://www.bioone.org/bioone/?reque....2192/1537-6176(2005)016[0102:TWONTW]2.0.CO;2
"In some areas of Canada's Arctic the temperature is expected to rise an estounding 15 degrees by 2050....Polar bears need sea ice to access prey."
Source: "Climate Change and Canada's National Park System," a overview by the David Suzuki Foundation of "Parks Canada 1997 State of the National Park's Report."
http://www.davidsuzuki.org/files/NatParkBak.pdf
