Reversing Extinction Risk


Thanks to Conservation for this note on the relationship between the proper identification of a species’ extinction risk and the amount of time practically required to do something about it:

Congratulations, you’ve made the IUCN Red List of Threatened Species! Now what? Is that enough to promise your salvation? Or will the increasing press of climate change on your vulnerable/endangered/critically endangered back spell your doom anyway?

A new study aimed to answer this question, of just how long placement on the Red List gives conservationists to try and save a species on its way to oblivion thanks to climate change. The answer is encouraging, with caveats: in general, we have decades to save vulnerable species, but only if we gather information on as many of the specific listing criteria (range area, population size, rates of population and range decline, and so on) as possible. If we fail at that, there are cases where a species could go from just-listed to extinct in the wild in less than 20 years.

“A serious concern is that climate change may already be impacting species, but so gradually that waiting until observable signs of decline are evident may prove to be too late to take effective conservation action,” wrote study authors from Stony Brook University in New York and University College London. There is a possibility that the criteria we generally use to assess whether species are endangered may not work very well over long time frames, especially for species that don’t live particularly long.

The usual method of evaluation considers changes to a population over the next three generations or ten years, whichever is longer. In the new study, the researchers used a modeling system that assessed species annually and calculated how much warning time the Red List criteria offer; that is, how long from listing to extinction if no conservation actions are taken?

When all of the Red List criteria are available to assess a species, the news is good: the median time to extinction is 62 years, and more than 99 percent of all species will last at least 20 years. And interestingly, the results contained a “hurry up!” message as well: 50 percent of the modeled species went extinct within 20 years of uplisting to “critically endangered” status, meaning taking action as soon as a species reaches “vulnerable” status is the way to go.

And then the less-good news: “Using a single criterion substantially decreased the warning time.” For some species, we simply don’t know as much about populations or ranges, so this is a real problem. Depending on which criterion in particular was used, warning times less than 20 years from “vulnerable” to extinct occurred up to just more than half the time.

The authors concluded, though, that this is generally an okay thing: the Red List exists to try and convince us to take action to save these species, and we seem to have time to do that. Climate change offers a new mechanism for extinction, but as long as we heed our own warnings on vulnerable and endangered species, there is no reason we can’t stave some of it off. As the authors write, “There is an urgent need to rethink conservation options for many species impacted by climate change, [but] there is no apparent need to invent new systems to assess species vulnerability to climate change.” – Dave Levitan | September 30 2014

Source: Stanton JC, Shoemaker KT, Pearson RG, et al (2014). Warning times for species extinctions due to climate change, Global Change Biology. DOI: 10.1111/gcb.12721

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