Post-Glacial Climate Change and Extinctions: Lessons for the Future?

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Global warming after the last Ice Age threatened to certain species (Photo by Madhav Pai)

Global warming after the last Ice Age threatened certain species: Photo by Madhav Pai

It’s commonly predicted that global warming will bring extinction for many animal species. A recently-published study by a team from Denmark’s Aarhus University has considered the effects of warming of the climate in the aftermath of the last Ice Age – and the findings from the past appear to corroborate the predictions for the future (Sandel et al, The Influence of Late Quaternary Climate-Change Velocity on Species Endemism.)

What is Climate Change?

Climate change is a current ‘buzz phrase’, often used to refer to human-induced global warming. In fact, the Earth’s surface temperature varies over cycles lasting for millions of years and the planet has repeatedly passed through phases in which it has been both considerably warmer and considerably cooler than at present.

Such change is driven by numerous complex and interacting factors, including mechanisms such as the configuration of the oceans and continents; variations in the Earth’s orbit around the sun; the amount of vegetation or ice cover on the Earth’s surface; and the position of ocean currents.

Human-induced climate change is a more recent concept and remains both highly controversial and politically sensitive. At its simplest, it can be understood as a situation in which human activity (most notably the burning of fossil fuels) has increased levels of carbon dioxide in the atmosphere, leading to an increase in average global temperatures.

The Aarhus University Study

Climate change affects habitat in many ways – by making environmental conditions unsuitable for a particular species, for example, or by affecting the types of soil or vegetation which are required for survival. Possible responses to such changes include migration to alternative geographical areas or retreat to smaller areas of habitat, or refuges.

Earth’s climate regularly experiences change: Image from NASA

The study focused upon the period of rapid and significant global warming which followed the melting of ice sheets following the last Ice Age around 21,000 years ago. Ecologists and computer scientists plotted the movements of key species as their habitat changed.

Study co-author Brody Sandel told Decoded Science that several factors influenced the risk of extinction, including climate change, the size of the range of each species and the ability of each to disperse. ‘The areas where we expect greatest extinctions in the future are areas where there are many small-ranged species with poor dispersal abilities and high expected future climate-change velocities’ he said via email on 10 October, 2011.

Why is the Study so Important?

Although past work has predicted losses based upon changes in climate, Brody Sandel notes that the current study is significant in that, rather than being predictive, it is based on evidence of migrations and extinctions which have actually taken place. For the first time ‘there is evidence that past climate changes have caused extinctions’.

As well as showing that there are lessons to be learned from past processes in terms of considering future patterns of migration and possible extinction, the study corroborates computer-modelling studies and gives some indication of which species are likely to be at highest risk.

Sources
Aarhus University. Ancient climate change has left a strong imprint on modern ecosystems. Accessed 10 October, 2011.

Sandel et al. The Influence of Late Quaternary Climate-Change Velocity on Species EndemismScience 6. (October 2011.) Accessed 10 October, 2011.

Warr, K., Smith S. et al. Changing Climate. Open University. (1998).

Wilson R.C.L., Drury S.A., and Chapman J.L. The Great Ice Age – Climate Change and Life. Routledge/Open University. (2000).

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