Predicting the effects of climate change on biodiversity is very much a growth industry, and understandably so. I’ve contributed to it myself (together with lots of friends), as I immodestly noted here in a previous posting. Many studies have predicted drastic increases in rates of extinctions, but then, why have so few species gone extinct during the past 2.5 millions years of recurring ice ages? This “Quaternary conundrum” is addressed in a new paper announced, and available for downloading, here. The conclusion of the 19 co-authors is that current approaches do not adequately take into account the factors which allow species to persist when conditions change for the worse. They make eight recommendations for improving predictions, ranging from better models to better validation of model results. Well worth reading.
Some clues to solving the conundrum can maybe be found in a recent review in TRENDS in Ecology and Evolution entitled Limits to evolution at range margins: when and why does adaptation fail?” One of the conclusions is that “poleward range shift is more common than the local adaptation that would enable populations to remain where they are.†Considering this together with the high human caused habitat loss and decimated populations it seems reasonable that this climate change period is going to be tougher for many species than previous ones. Nevertheless, the quartenary conundrum is thought provoking. The IPCC in their last report on Impacts, Adaptations and Vulnerability warns that “Approximately 20-30% of plant and animal species assessed so far are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5-2.5ËšC†In a media report this very easily translates into “20-30% of species likely to become extinct by global warming†and this gives association to earlier doomsday prophecies such as the much cited prediction by Paul Ehrlich in 1981 saying that half of the earth’s species would be extinct by year 2000 –an easy target for the skeptics attacking the “environmental litanyâ€.