Continued....
The fact is that we live in a warm period known as the Holocene where temperatures rise and fall naturally but don't go to extremes. These warm periods appear to be cyclical – the last one being before the last ice age which ended about 115,000 years ago. They seem to last for anywhere up to 50,000 years. That may seem like quite a long time but for vast majority of the time, the Earth is gripped by an Ice Age. So we should consider ourselves quite lucky to live in the period we do.
http://en.wikipedia.o...e_Age_Temperature.png
As I'm sure you'll notice from the above graph, the last interglacial maximum temperature was about 5 degrees warmer than what we have today – with clearly no adverse effects on the Polar Bears – seeing as they still exist as a species despite living through a significantly warmer period than exists today that lasted for several thousand years.
The next time you see or hear someone claiming that such and such a species is about to become extinct because of GW/CC ask yourself this:
If species take millions of years to evolve and yet can be killed by a cold climate, how come those same species are still around today, having obviously survived several Ice Ages and warmer-than-today Interglacials?