Interglacial refugia?!

A couple of blogs ago I was talking about glacial refugia and how, during glacial periods, expanding ice cover forced species to migrate southwards in order to reach warmer climates. This is a natural phenomena and species have always adapted to climate change in the past. However, is there such thing as 'interglacial refugia'?! Do species in the sub-polar regions have to move closer to the poles during interglacial warm periods?!

The answer is - YES.

In the past, during glacial periods, cold adapted species such as the arctic fox had much larger populations than present. This was because as the climate became colder and ice cover increased, these species had larger areas to live and breed in and so their populations increased (expansion without rear contraction). Then, as ice started to melt and the earth shifted into an interglacial, these species could no longer survive in these warming areas and were pushed back towards the poles. The interglacial we are currently experiencing has reduced populations and contracted ranges of polar species.

Noone is quite sure when the current interglacial is going to end, some scientists say it should have already ended while others say it has around another 10,000 years to go. However, the number of species currently moving north due to climate change has no reflection on interglacial refugia. Present rates of northward movement are much higher than any known rates of expansion/contraction in the past.

References:

[1] Stewart et al (2011) 'Refugia revisited: individualistic responses of species in space and time', Proceedings of the Royal Society, 277, 661 - 671.