Amphibian Extinctions: Is Global Warming Off the Hook?

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"The major message is that we need to be careful."

But J. Alan Pounds, resident scientist at Costa Rica's Monteverde Cloud Forest Preserve and an author of previous research on the topic, maintains climate change is a key factor in the extinction crisis.

"There is a clear link between global warming and amphibian declines," he said, citing a growing body of evidence, including a recent study in Yellowstone National Park.

"The analysis by Rohr et al. is seriously flawed, as we will demonstrate in due course."

Heated Debate

Some scientists say the fungus is an invasive species, entering an ecosystem and wreaking havoc on species with no natural defenses.

Pounds and others believe that rising daytime and nocturnal temperatures are narrowing the gap between daily highs and lows.

Fewer temperature extremes are advantageous for chytrid fungus, which grows and reproduces best at temperatures between 17 and 25 degrees Celsius (63 and 77 degrees Fahrenheit).

The new research suggests neither theory has it exactly right.

For example, Rohr explained that, although extinctions increased significantly in the 1980s, that period did not show smaller swings between average daily high and low temps that would theoretically produce more fungus growth.

In the 1990s, daily temperature swings were smaller, but amphibian extinctions declined during that period, the study concludes.

Rohr and colleagues conclude that an unknown mix of factors is likely endangering amphibians.

Sorting it all out remains a high priority—and for many amphibians, time could be running out.

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