Global warming causes frog extinctions


Plenty Magazine – May 23, 2007

This is a sad article if it is true. Evidently several species of frogs have become extinct and some scientists believe that this extinction was caused by global warming. While I am well aware that certain amphibians (esp. frogs) are very susceptible to changes in their environment, I am concerned that this article does not live up to the burden of proof.

A few of my concerns:

  • Global warming should be more accurately termed “Northern Hemisphere Warming” since much of the measured increase was in the northern half of the planet. Costa Rica is very close to the equator – what was the increase in temperature for Costa Rica in the last 50 years? We really do not need to worry about average global temperatures if we are discussing the effect on a species that is very local.
  • If we assume that the population has decreased since 1972, as the report suggests, then we must assume that some baseline study was done at that time. How does this baseline compare to the studies of these animals in 1950 and 1930? The conclusion that this is an issue in the latter quarter of the 20th century would be much stronger if we knew what the population level was in the first three quarters.
  • The article tends to blame a certain fungus. What are the growth characteristics of this fungus? Does it grow and spread faster with an increase in temperature? Where did it come from (presumably the south if it prefers a warmer climate)? How fast is is advancing? Is there another species that used to live on this fungus that has been removed from the environment?

While it is likely that some scientist has looked into these fairly obvious questions, I could not find any background that alleviated my concerns.

Global warming is the top suspect for the disappearance of 17 amphibian species from Costa Rican jungles

Five of the amphibian species were found only in Costa Rica, meaning their disappearance from the country’s jungles spells extinction, said Alvaro Herrero, a biologist with Costa Rica’s National Biodiversity Institute.

Scientists have yet to identify a precise mechanism for the disappearance of the amphibians, which began decades ago, but a prime suspect is a fatal fungus that has invaded their habitats

Several studies in recent years have linked the rapid disappearance of many of the world’s frog and toad species to global warming.

Scientists say the amphibian die-off is a harbinger of things to come in the biologically rich tropical forests of Costa Rica.

“It’s going to be a fact that we see a large extinction,” said Rodrigo Gamez, president of the biodiversity institute.

The precise reason for the La Selva decline is not known, but scientists suspect that higher temperatures are inhibiting plant growth and thus diminishing the volume of decomposing leaves in which the amphibians thrive.

You can read the entire article here.

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