A University of Alberta scientist is part of an international research team proving, for the first time, that global warming is behind an infectious disease epidemic wiping out entire frog populations and forcing many species to extinction.
"There is absolutely a linkage between global warming and this disease - they go hand-in-hand," said Arturo Sanchez-Azofeifa, a professor in the U of A's Department of Earth and Atmospheric Sciences and co-author of a research paper appearing in the current edition of the prestigious journal Nature.
Sanchez-Azofeifa worked with an international research team led by Dr. Alan Pounds from Costa Rica's Monteverde Cloud Forest Preserve and Tropical Science Centre. Accounting for such things as deforestation, the scientists investigated how the Monteverde harlequin frog vanished along with the golden toad 17 years ago from the mountains of Costa Rica. The researcher say about 67 per cent of the 110 species of the harlequin frog, which only existed in the American tropics, have met the same fate due to a pathogenic fungus called Batrachochytrium dendrobatidis.
The researchers discovered that between 1975 and 2000, air temperature for the tropics increased by 0.18 degrees per decade, triple the average rate of warming for the 20th Century. The paper states this warming has reduced mist frequency at Monteverde by raising the heights of cloud formation which may promote the survival, growth and reproduction of the fungi.
After analyzing the relationship and timing between the demise of the species and the changes in surface and air temperatures, the scientists conclude "with high confidence," that large-scale warming is a key factor in the disappearance of many of the amphibian populations present in cloud forest environments.
"With this increase in temperature, the bacteria has been able to increase its niche and wipe out large populations of amphibians in the Americas," said Sanchez-Azofeifa, who analyzed satellite images to extract deforestation rates and forest cover extent data used on the modelling component of the study.
"Once a species is gone we can't do much to bring it back. What we need to do is worry about what will be happening in the future. How many species in tropical environments are going to disappear before people realize how serious climate change is? This is not an esoteric thing that is only important to the scientific community - it affects all of us. We are showing that there are real consequences to inaction."
The study comes 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 are threatened with extinction - a figure that is far greater than that for any other group of animals.
"When we talk about climate change, there is so much focus on industrialized countries, but people are ignoring other ecosystems that may be extremely sensitive to climate change, such as dry and cloud forest environments," said Sanchez-Azofeifa. "Its impact goes beyond what we can observe here in Canada and the north, and the situation is obviously very grave."
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