Friday, 9 December 2011

A paleoecological perspective

This post stays on the subject of global biodiversity, as I think an interesting additional perspective to the theoretical one in the last post can be found in Willis et al. (2010). This paper reviews the use of paleoecological archives to understand the rates and nature of ecological responses to climate change, partly with the aim of assessing the reliability of climate-biodiversity models with real data. Willis et al. note a huge discrepancy between a modeled and historical scenario.


Models predict that rising temperatures and CO2 could transform 80% of Earth's tropical rain forest into savannah in the next 50 years; this would be a severe loss of biodiversity. However, pollen and plant macrofossils from dated tropical lake archives show that during the Eocene thermal maximum, a period with higher temperature and CO2 levels than those predicted by the models for 50 years time, extremely diverse tropical rain forest extended far further over the globe than it does today. Willis et al. suggest the reason behind this is a lack of understanding of atmospheric dynamics (with regard to CO2) in the model in question. I think this real-data perspective is a hopeful one; perhaps climate change would actually increase global biodiversity if other anthropogenic threats could be 'treated'.

References:
Willis, K.J., R.M. Bailey, S.A. Bhagwat and H.J.B. Birks (2010) 'Biodiversity baselines, thresholds and resilience: testing predictions and assumptions using palaeoecological data', Trends in Ecology & Evolution, 25, 10, 583-91.

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