Wednesday, October 1, 2014

Warning times for species extinctions

Climate change is expected to result in heightened risk of extinction for many species. Because conservation scientists are just starting to understand this threat, many have concluded that current risk assessment protocols, such as the International 'Red List' published by IUCN will fail to identify many species at risk from climate change because they are based on rules established in the 1990s,  .

A team of researchers from the US and the UK quantitatively tested the the performance of the IUCN Red List system to see if it can serve as a warning system for identifying species vulnerable to climate change. They used computer models to project the future abundance of 36 species of herpetofauna under climate change. Subsequently they performed what they call virtual Red List assessments, following the IUCN guidelines to determine the Red List Status (e.g., "Critically Endangered") of each species throughout the simulation.Currently, there are 22,176 species listed as threatened in the IUCN Red List, of these, about 21% are listed at the highest threat level of Critically Endangered.

Their study shows that the Red List system would actually be able to identify species at risk and could provide several decades of warning time for species that might go extinct because of climate change. Their simulations show that the time between the identification of a species as threatened and the time it goes extinct is on average some 60 years assuming that no conservation action has been taken. The warning time can be as short as 20 years for many species, especially if information about their populations is limited. This in turn may not be enough time for saving this particular species. The authors also cautioned that whether the warning time provided by the IUCN Red List system is sufficient to prevent extinctions depends on how fast conservation actions can lead to recovery of species.

Another important finding of the study is the need to initiate conservation action as soon as a species is listed at the lowest threat level, which is "Vulnerable" in the IUCN Red List system. After a species is listed at the highest level (called "Critically Endangered"), the warning time is predicted to be shorter than 20 years for most species, even with a sufficient amount of data. Most species at the highest threat level have already declined to very low levels or exist in very small areas, and as a result they are already on the brink of extinction.

Because the effects of climate change are thought to be gradual, but persistent there is concern that species may not manifest the threatened indicators within the time frames used by the IUCN Red List. We found that IUCN Red List will likely provide several decades of warning time for most species. Thus, we conclude that although climate change brings many new conservation challenges, and therefore there is an urgent need to rethink conservation options for many species impacted by climate change, there is no apparent need to invent new systems to assess species vulnerability to climate change.

That is good news as we already seem to have some of the tools that we are going to need for identifying species vulnerable to climate change. This would mean that instead of spending a lot of time developing new models and methods (I am not saying that we should abandon that entirely) we should put more emphasis on gathering the necessary data to assess Red List status of many more species. 

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