Originally Posted by
texastig
In 1000 AD, Leaf Ericsson founded colonies on Greenland and present day Newfoundland, which he called Vinland because of the grapes that grew freely then. Many scientists claim the average temperature was 7 degrees warmer then than it is now. The polar bears survived this natural phenomena and will also survive this one.
Thanks,
TT
A very small bit of research would reveal to you that this may not be so. From Wikipedia (which has all the citations and research cited there), first the concerns:
The key danger posed by global warming is malnutrition or starvation due to habitat loss. Polar bears hunt seals from a platform of sea ice. Rising temperatures cause the sea ice to melt earlier in the year, driving the bears to shore before they have built sufficient fat reserves to survive the period of scarce food in the late summer and early fall. Reduction in sea-ice cover also forces bears to swim longer distances, which further depletes their energy stores and occasionally leads to drowning.Thinner sea ice tends to deform more easily, which appears to make it more difficult for polar bears to access seals. Insufficient nourishment leads to lower reproductive rates in adult females and lower survival rates in cubs and juvenile bears, in addition to poorer body condition in bears of all ages.
In addition to creating nutritional stress, a warming climate is expected to affect various other aspects of polar bear life: Changes in sea ice affect the ability of pregnant females to build suitable maternity dens. As the distance increases between the pack ice and the coast, females must swim longer distances to reach favored denning areas on land. Thawing of permafrost would affect the bears who traditionally den underground, and warm winters could result in den roofs collapsing or having reduced insulative value. For the polar bears that currently den on multi-year ice, increased ice mobility may result in longer distances for mothers and young cubs to walk when they return to seal-hunting areas in the spring. Disease-causing bacteria and parasites would flourish more readily in a warmer climate.
Problematic interactions between polar bears and humans, such as foraging by bears in garbage dumps, have historically been more prevalent in years when ice-floe breakup occurred early and local polar bears were relatively thin. Increased human-bear interactions, including fatal attacks on humans, are likely to increase as the sea ice shrinks and hungry bears try to find food on land.
And the info on predictions and the possibility of adaptation:
The U.S. Geological Survey predicts two-thirds of the world's polar bears will disappear by 2050, based on moderate projections for the shrinking of summer sea ice caused by global warming.(...)
Predictions vary on the extent to which polar bears could adapt to climate change by switching to terrestrial food sources. Mitchell Taylor, the director of Wildlife Research for the Government of Nunavut, wrote to the US Fish and Wildlife Service arguing that local studies are insufficient evidence for global protection at this time. The letter stated, "At present, the polar bear is one of the best managed of the large Arctic mammals. If all Arctic nations continue to abide by the terms and intent of the Polar Bear Agreement, the future of polar bears is secure.... Clearly polar bears can adapt to climate change. They have evolved and persisted for thousands of years in a period characterized by fluctuating climate."
(...) However, many scientists consider these theories to be naive (...) An additional risk to the species is that if individuals spend more time on land, they will hybridize with brown or grizzly bears.