Originally posted by RicS:
Hi all. [snip]
Polar Bears.
Yeah, sure, polar bears are going extinct because of global warming that is either 30 years old or maybe 80 if you really fudge the figures. Sorry, it just doesn't happen that way. Polar bears evolved to their modern form many hundreds of thousands of years ago and - without particular expertise in polar bears - I'm guessing they were not a great deal different for between 2 million and 10 million years.
From what I've heard, brown bears/grizzlies and polar bears are closely related. I don't know if polar bears evolved from browns, or if they both evolved from a common ancestor.
As to seals, these are just part of a polar bears diet but a really important part. Less ice actually means more seals but I won't go into the reasons why warmer conditions mean more seals.
I would guess that depends on the species of seal and their primary food source.
Less ice means the seals will travel further north, not that there will be less of them. And actually from what I understand, polar bears need breaking pack ice to easily catch seals. They do not hunt in packs at all. Males are solitary. Females may have cubs but large groups only get together in areas of abundant food supply but not to hunt in any pack. I would suggest global warming is not at all relevant to how many seals individual polar bears are able to catch and eat.
That is true about the social life of polar bears. But global warming is key to the numbers of seals polar bears can catch and eat. Polar bears are good swimmers, as land animals go, but their swimming abilities are no match for those of a seal. They don't hunt them while swimming, they hunt them by laying in wait at breathing holes in the pack ice. Less pack ice = fewer breathing holes = fewer opportunities for seal hunting.
Mammoths were pretty much the same for more than a million years. They went extinct during the last glacial period. It was actually the coldest period of the cycles between glaciations and interglacial periods. You certainly could not blame any type of warming for their extinction. Actually a great many large beasts went extinct in that 10,000 to 20,000 time frame, including a wombat like creature in Australia about 15 feet tall. (And that one really goes against climate change issues because Australia is very much immune to climate change of the extent that would threaten larger animals no matter whether it is a glaciation or interglacial period. It does not get covered with snow or ice nor does the climate dramatically change with world warming). None of these beasts went extinct because of warming.
I would avoid blanket statements like that, but you may be right. There is much speculation that many of the large Pleistocene mammals were hunted to extinction by humans.
Polar bears have managed to survive many periods of warm periods. Even in the middle of the warmest interglacial period, you still have ice over the Antarctic and over the North Pole and pack ice in the high northern latitudes. If it retreats so do the polar bears, and the seals. Indeed, if there is a late summer polar bears have real problems, food wise.
Polar bears need the pack ice for successful hunting, and they need it to be relatively close to land. Being forced to swim miles out to the pack ice takes a toll on their resources. Though adults are known to be able to swim 50 miles or more, they have to be in shape, and have the stored energy to do so.
