Ice Age climate change has been rapid, pervasive and frequent. For instance, during the last 2.6 million years, the duration of the current Ice Age, there have been 104 major fluctuations between global cold and global warmth. Each of the major fluctuations was itself complex, encompassing ‘minor’ changes of up to 5 degrees centigrade in average annual temperature. As temperature rose and fell, so did global sea level, by up to 130 metres. These changes did not lead to catastrophic global extinctions of the earth’s biota. The extensive animal and plant communities of the past, undisrupted by human development, could adapt to the changes by migrating, or by shrinking or expanding populations. In shrinking animal populations, of course, there is an excess of deaths over births, by starvation or predation. Our current human population, faced with comparable climate change, will have a similar choice, and there is now little room for migration.
Sources The general course of climate history in the last 2.6 million years (the Quaternary Period of geological time) is now generally agreed and non-controversial. Effective summaries of the complex course of Quaternary climate are given by standard texts such as:
- Alverson, K.D., Bradley, R.S. & Pederson, T.F. (eds) Paleoclimate, global change and the future. Springer, Berlin.
- Lowe, J.J. & Walker, M.J.C. 1997. Reconstructing Quaternary environments (2nd edition). Longman.
- Roberts, N. 1998. The Holocene (2nd edition) Blackwell: Oxford.
- Wilson, R.C.L., Drury, S.A. & Chapman, J.L. The Great Ice Age. Routledge/Open University.
Current research is focussing on the detailed course of this climate change, and also on trying to disentangle cause from effect, and some of the references listed below (particularly those on the ice core work) give a flavour of this. A recent paper on aspects of the general pattern of Ice Age climate is:
- Liu, Z. & Herbert, T.D. 2004. High-latitude influence on the eastern equatorial Pacific climate in the early Pleistocene epoch. Nature, vol. 427, pp. 720-723.