Geoscience Reference
In-Depth Information
Earth warms again. To do this we need to see how the climate is changing today and
this is the focus of the next chapter.
Past glacials and interglacials have also had a genetic impact on species as they have
expanded from, and retreated to, their respective refugia. In a world without humans
this broad pattern of genetic forcing and glacial-interglacial ecological change would
have continued with future glacials and interglacials. However, our planet does have
humans (and hence has a changed and more ecologically fragmented landscape) and
we do have global warming. Once this warming takes us beyond past interglacial
analogues (likely in the 21st century), then species' respective genetic mix (hence
characteristics) may not always enable them to flourish as they have during the past
2 million years of the Quaternary or even earlier, in the Pliocene. Further, given that
component species may not flourish, there is the possibility in some circumstances
that global temperatures greater than past interglacials, let alone human land-use
impacts, could result in ecosystem dysfunction.
Finally, the growth of human civilisations during the current (Holocene) interglacial
has largely been dependent on domesticating species for food. This domestication
has taken place numerous times over the past several thousand years during which
the global climate has been comparatively stable compared to the glacial-interglacial
range. As we shall see, 21st-century warming is likely to take us beyond this range
and so is likely to impact on global food security. The future of food security and
climate change will be discussed in Chapter 7.
4.8 References
Abbott, R. J., Smith, L. C., Milne, R. J., Crawford, R. M. M., Wolff, K. and Balfour,
J. (2000) Molecular analysis of plant migration and refugia in the Arctic. Science ,
289, 1343-6.
Allen, J. R. M., Bradnt, U., Brauer, A. et al. (1999) Rapid environmental changes in
southern Europe during the last glacial period. Nature , 400, 740-3.
Armitage, S. J., Jasim, S. A., Marks, A. E. et al. (2011) The southern route “Out of
Africa”: Evidence for an early expansion of modern humans into Arabia. Science ,
331, 453-6.
Barber, D. C., Dyke, A., Hillaire-Marcel, C. et al. (1999) Forcing of the cold event
of 8,200 years ago by catastrophic drainage of Laurentide lake. Nature , 400,
344-8.
Barker, S., Diz, P., Vautravers, M. J., Pike, J. et al. (2009) Interhemispheric seesaw
response during the last deglaciation. Nature , 457, 1097-1102.
Barnosky, A. D., Koch, P. L., Fernac, R. S., Wing S. L. and Shabel, A. B. (2004)
Assessing the causes of late Pleistocene extinctions on continents. Science , 306,
70-4.
Bennett, K. D., Haberle, S. G. and Lumley S. H. (2000) The last glacial-Holocene
transition in southern Chile. Science , 290, 325-8.
Berger, A. and Loutre, M. F. (2002) An exceptionally long interglacial ahead. Science ,
297, 1287-8.
Search WWH ::




Custom Search