In the famed Costa Rican cloud forests, for example, the Monteverde harlequin frog disappeared in the late 1980s, as did the golden toad, whose much-publicized extinction, said Pounds, "was the first sign of this emerging threat to species survival."
Using records of sea-surface and air temperatures, Pounds and colleagues show that harlequin frogs are disappearing in near lockstep with changing climate. According to the scientists, the Earth's rising temperatures enhance cloud cover on tropical mountains, leading to cooler days and warmer nights, both of which favor the chytrid fungus. The organism grows and reproduces best at temperatures between 63 to 77 degrees Fahrenheit (17 to 25 degrees centigrade).
The fungus kills frogs mostly in cool highlands or during winter, implying that low temperatures make it more deadly. So the idea that it flourishes in warm years, which the evidence now supports, is new.
The study results come at a time of growing concern about the future of amphibians. The Global Amphibian Assessment, published in 2004, found that nearly one-third of the world's 6,000 or so species of frogs, toads and salamanders face extinction--a figure far greater than that for any other group of animals.