Polar Bears do not need sea ice to survive !!! that is total nonsense !!!
Climate Change Impacts
Sea ice is the predominant feature of the arctic seas, and global warming caused by greenhouse gas emisions
is expected to cause a reduction in its thickness and extent. Arctic shelf seas are among the most productive
in the world and large numbers of organisms from all trophic levels can be found along ice edges, leads and
polynyas where the interaction of ice, sunlight and water currents is greatest (Sakshaug et al. 1994).
Reductions in the extent of sea ice will undermine the productivity of the northern oceans. Of concern as the
ice melts is the loss of ice-dependant prey species for predators like the polar bear (Tynan and DeMaster, 1997).
The seasonal cycle of melting ice creates vertical mixing in the ocean column and allows nutrient-rich water
to reach the surface. Colony-building diatoms and blue-green algae flourish on the underside of ice floes. In
the spring, as sunlight returns to the northern high latitudes and the pack ice retreats north, these algae seed
a bloom of phytoplankton in the layer of nutrient-rich brackish water that forms on top of the cold, dense sea
water below. Zooplankton and small crustaceans, such as copepods, amphipods and krill, feed on this bloom.
These in turn, serve as food for fish (particularly arctic cod), seals, seabirds, and other predators. But it is in
the open water of leads and polynyas where productivity is highest and top level predators—like the polar
bear—feast on the abundance of ice-dependent species assembled there (Sakshaug et al. 1994). Due to its
position at the top of the arctic marine food web, the polar bear is an ideal species through which to monitor
the cumulative effects of climate change in the arctic marine ecosystem (Stirling and Derocher 1993).
Indigenous communities along the coast of the northern Bering and Chukchi Seas have noticed substantial
changes in the marine ecosystem since the 1970s. Alaska Natives, for example, have experienced warmer
winters, early spring break-up, and thinner than usual ice (Pungowiyi 2000). This traditional knowledge echoes
the scientific evidence. Throughout the 20th century, the following scientific observations have been made:
• Although not geographically uniform, air temperatures in the Arctic have increased by about 5°C
over the last 100 years (Serreze et al. 2000).
• Since 1972, a 10 per cent decrease in snow-cover extent across the northern hemisphere has been
observed (Brown, 2000).
• Between 1978 and 1996, arctic sea ice extent decreased by approximately 3 per cent per decade
(Parkinson et al. 1999);
Figure 2 illustrates that spring sea ice extent in the Nordic Sea has been
reduced by 33 per cent over the past 135 years (Vinje 2001).
Sea ice is critical to the survival of polar bears. It is the platform from which they hunt because it is there
that their primary prey—ringed and bearded seal—are found. Ringed and bearded seals are in turn dependent
on sea ice as it is there that they rest, give birth and raise their pups. Regional variation in the seasonal distribution
and extent of sea ice has been shown to have significant effects on the survival of seals and consequently
on polar bears (Stirling 1997).http://www.worldwildlife.org/climate/Publi...aryitem4927.pdf