Tuesday, January 31, 2006

Kermit Was Right: It's Not Easy Being Green

Global warming has killed off at least 70 frog species by exacerbating outbreaks of a deadly fungal disease, providing the first scientific evidence that world-wide climate change decreases ecological diversity, according to a study published this month in the journal Nature.

The international team of scientists suggests that approximately two-thirds of all harlequin frog species, endemic to Central and South America, have disappeared after falling victim to a chytrid fungus that thrives as a result of temperature increases that have occurred since 1970. Scientists have been keen to understand what has caused these extinctions, and while global warming has been a popular buzz word, this is the first time that researchers have demonstrated that it has, indeed, played a key part.

"Disease is the bullet killing frogs, but climate change is pulling the trigger," says J. Alan Pounds, the lead researcher and a Resident Scientist at the Monteverde Cloud Forest Preserve in Costa Rica, in a prepared statement.

After comparing extinction rates to tropical sea surface and air temperatures for each year, the researchers found that, as tropical temperatures increased, extinction rates did too something they found confounding, because the fungus actually flourishes at more moderate temperatures.

The scientsts were able to resolve this "climate-chytrid paradox" after discovering that as tropical temperatures increase, evaporation from the oceans does too, resulting in increased cloud formation where the frogs live. Because clouds have a moderating effect on temperature, cloudy days are actually cooler on average, while the nights are warmer. And because the fungus, which is lethal to frogs, thrives in the more temperate cloudy climate, it has managed to wipe out frog populations in large numbers.

In 2004, the Global Amphibian Assessment published that nearly one-third of the world's frogs, toads and salamanders are close to extinction but amphibians are not the only animals being endangered. Scientists also suggest that global-warming induced epidemics threaten musk oxen in the Arctic and sub-Arctic as well as pine trees in the Rocky Mountains.

Because this research implicates global warming as an undeniable threat to ecological diversity, Pounds considers it imperative to address the problem immediately. "There is clearly an urgent need for a rapid transition to cleaner energy sources," he says in a prepared statement. "I reiterate the call for a bold initative, on the order of the Manhattan and Apollo projects, to put an end to humanity's dependence on fossil fuels."


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