March 25, 2008

Global warming NOT killing frogs (just like we told you)

Filed under: Extinctions

Declining frog populations have once again made their way into the news, but this time, it is because new research concludes that global climate change IS NOT the reason behind their disappearance.

While this seems to be big news for some, we have been telling you this ever since the stories that attempted to link amphibian declines to global warming first appeared.

The biggest climate-change-is-killing-frogs story was published in Nature magazine in 2006 by Alan Pounds and colleagues titled “Widespread Amphibian Extinctions from Epidemic Disease Driven by Global Warming.” It claimed a link between climate change and the rapid declines to near extinction of various toad and frog species across Central and South America. It quickly made headlines worldwide.

Concurrently, we pointed out just how weak the conclusions of Pounds et al. really were and we wondered aloud as to just what had become of the peer-review process at the prestigious Nature magazine.

Now, a new study proves that we were smack on the mark, and the news media is now scrambling to cover itself.

Dr. Karen Lips from the Department of Zoology at Southern Illinois University and colleagues just published the results of their review of the evidence linking climate change to amphibian declines in Central and South America. Here are their goals and conclusions:

We review the evidence for the role of climate change in triggering disease outbreaks of chytridiomycosis, an emerging infectious disease of amphibians. Both climatic anomalies and disease-related extirpations are recent phenomena, and effects of both are especially noticeable at high elevations in tropical areas, making it difficult to determine whether they are operating separately or synergistically. We compiled reports of amphibian declines from Lower Central America and Andean South America to create maps and statistical models to test our hypothesis of spatiotemporal spread of the pathogen Batrachochytrium dendrobatidis (Bd), and to update the elevational patterns of decline in frogs belonging to the genus Atelopus. We evaluated claims of climate change influencing the spread of Bd by including error into estimates of the relationship between air temperature and last year observed. Available data support the hypothesis of multiple introductions of this invasive pathogen into South America and subsequent spread along the primary Andean cordilleras. Additional analyses found no evidence to support the hypothesis that climate change has been driving outbreaks of amphibian chytridiomycosis, as has been posited in the climate-linked epidemic hypothesis. Future studies should increase retrospective surveys of museum specimens from throughout the Andes and should study the landscape genetics of Bd to map fine-scale patterns of geographic spread to identify transmission routes and processes.

You read that right, they found no evidence to support the hypothesis that climate change is behind the outbreaks of the disease that is causing the frog die-offs. Whether or not you consider this old news or new news probably depends on whether or not you read World Climate Report.

This is yet another example showing that flimsy, but provocative findings that anthropogenic climate change is destroying the world quickly and easily make their way into prestigious scientific journals, the global media, and scientific assessments, and that it takes a long time to dispel these myths, despite evidence to the contrary that, in many cases, has been readily available all along. A service that we are more than happy to provide through our World Climate Report blog.

Congratulations to Dr. Lips and colleagues for their continued efforts to set the record straight as to the true causes of the amphibian declines. Dr. Lips and colleagues join the ranks of numerous scientists worldwide who are more interested in scientific truth than in global warming hype—regardless of what their personal beliefs concerning anthropogenic climate change, its potential impacts, and policies aimed at ameliorating the impacts may be. This is how science moves forward.

Reference:

Lips, K.R., Diffendorfer, J., Mendelson III ,J.R, Sears, M.W., 2008. Riding the Wave: Reconciling the Roles of Disease and Climate Change in Amphibian Declines. PLoS Biol, 6(3), e72 doi:10.1371/journal.pbio.0060072

Pounds, J. A., et al., 2006. Widespread amphibian extinctions from epidemic disease driven by global warming. Nature, 439, 161-167.




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