The Quartenary Conundrum

The Quartenary Conundrum is this: While current empirical and theoretical ecological forecasts suggest that many species could be at risk from global warming, during the recent ice ages surprisingly few species became extinct.

In a recent paper in BioScience, Forecasting the Effects of Global Warming on Biodiversity (pdf), Daniel Botkin et al. state that

Fossil evidence and recent ecological and genetic research, along with specific problems with present forecasting methods, lead us to believe that current projections of extinction rates are overestimates. Previous work has failed to adequately take into account mechanisms of persistence. […]

Until recently, it was thought that past temperature changes were no more rapid than 1 degree Celsius (°C) per millennium, but recent information from both Greenland and Antarctica, which goes back approximately 400,000 years, indicates that there have been many intervals of very rapid temperature change, as judged by shifts in oxygen isotope ratios. Some of the most dramatic changes (e.g., 7°C to 12°C within approximately 50 years; Macdougall 2006) are actually of greater amplitude than anything projected for the immediate future. […]

What, then, is the answer to the Quaternary conundrum? The answer appears to lie in part with the ability of species to survive in local “cryptic” refugia, that is, to exist in a patchy, disturbed environment whose complexity allows faster migration than forecast for a continuous landscape, within which species move only at a single rate. The answer also lies in part with greater genetic heterogeneity within species, including local adaptations,which allows rapid evolution. For example, populations close to latitudinal borders are likely to be better adapted to some environmental changes than the average genotype. However, the conundrum is not completely solved, and some important genetic research suggests that species are more vulnerable than the fossil record indicates. A fuller solution to the conundrum will be important for improving forecasts of climate change effects on biodiversity.

HT Carl Zimmer.

Note that this is not a call for complacency, it is a call for better models of climate change effects on extinctions.

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One thought on “The Quartenary Conundrum

  1. In the older Quaternay times habitat was probably not so fragmented as it is today. Species were able to disperse ‘freely’ along the space, thus responding themselves searching for their niche. So the reflection of past events in today’s days seems unrealistic. The context is different…

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