Submitted by Fred Adams, Dec 30, 2006 14:54

Over the last 20,000 years, the earth has seen dramatic variations in glaciation, a phenomenon which has recurred periodically in the recent geologic past. We are now at or approaching another of many periodic glaciation minima. At a near term maximum, glaciation may have extended to the central US. Dramatic climate shifts are a fact of life on earth.

Polar Bears have survived these changes. Their numbers may have waxed and waned.

Polar bears feed mostly on seals caught on ice subject to recurrent break-up and re-freeze. Their feeding habits/locations are sensitive to ice conditions. Their prey are not commonly available on hard pack ice. Mammalian predators are reasonably adaptable animals; polar bears might successfully adapt their habits to accommodate some degree of climate change, though this is not a given.

Observed global warming over ~ the last 40 years amounts to 0.1 to 0.3 degrees C, depending on measurement method. While temperature may be reliably measured to greater precision, the measurement of "global average temperature" is subject to spatial and temporal sampling errors that may render these results non-representative.

Prior to the last ~ 100 million years, there was no glaciation on earth, a condition which describes most of the geologic past. There were intermittent long-term glaciations at three prior times, as far back as 750 million years. Polar bears and humankind were not a factor.

Note: Comments are screened, and in some cases edited, before posting. We reserve the right to reject anything we find objectionable.