Habitat Destruction | Pollution & Pesticides | Climate Change | Invasive Species | Over-Harvesting | Infectious Diseases
Climate Change & Global Warming
Unlike reptiles or birds, which have hard-shelled eggs, amphibians have jelly-like, unshelled eggs that cannot survive desiccation. Amphibians need moist climates to reproduce, and this makes them extremely sensitive to climate change. Frogs in high mountainous areas are most affected by global warming.
Climate Change in Tropical Regions
In many areas of the world, especially in the tropics, mountainous areas have extremely high amphibian biodiversity. For instance, some sites in the mountains of Costa Rica and Panama may have up to 60 species. In these tropical montane areas, many of the amphibians live in cloud forests, and lay their eggs in the moist leaf-litter. As the eggs are laid away from water bodies, the embryos bypass the aquatic tadpole stage and hatch directly into tiny froglets. These 'direct-developing' species (like the Marsupial Frog Assa darlingtoni pictured here) are under serious threat from global warming, which acts to raise the cloud levels. If the cloud's average elevation increases a few hundred meters, the frogs at the newly-exposed lower elevations lose their habitat (and their lives) as the soil dries.
While the affected frogs could potentially move up the mountain to find cool, moist habitat, many frog species already live at the tops of mountains, so when their habitat dries or warms, they have nowhere left to go. Another issue is that mountains are shaped like cones, and at a given elevation, there is less total area at higher elevations, so an amphibian that is forced to higher elevations would find itself in potentially crowded conditions. Further, some frog species live only on a single mountain range, or even on a single mountain, so when problems arise they are extremely prone to extinction.
Climate change also affects host-parasite relationships. The deadly chytrid fungus (Batrachochytrium dendrobatidis) is expanding its elevational range in the high Andes of Peru as the glaciers melt and new lakes are formed. The fungus was recently found infecting Telmatobius frogs as high as 5348m elevation.
Climate Change in Temperate Regions
Pond-breeding species are dependent on water bodies that do not dry up before their tadpoles can metamorphose. In Yellowstone National Park, droughts have been increasing over the last 50 years, and 25% of the ponds that existed in the early 1990's no longer fill with water. As the four amphibian species in the park are pond-breeders, it is not surprising that three of the four species are thought to now be declining in numbers, such as the Columbia Spotted Frog (Rana luteiventris) pictured here. Learn more about climate change in Yellowstone here.
Yellowstone is the world's oldest protected area, having been preserved as a National park since 1872, so if climate change is already affecting the park's wildlife, we have to assume that climate change is having an even more significant effect elsewhere in the world, where habitat destruction, pollution and pesticides, and over-harvesting are likely to compound matters.
Global warming has also been shown to negatively affect common toads (Bufo bufo) in the United Kingdom. In warm years, females were thinner, laid fewer eggs, and had reduced survival rates. Read more in this article by C.J. Reading.
Please help us stop global warming!
Please read our How To Help page, which lists many ways to reduce your effect on the planet, including ways to reduce your carbon footprint. And definitely watch this fabulous video on the relationship between beef and global warming; it features Bill Nye (the Science Guy).
We also need your financial support. Please donate $20 or become an official member of SAVE THE FROGS!, so that we have the funds to educate our society and businesses about global warming and ways to prevent it, and to force our politicians to make the changes necessary to protect frog species from their imminent extinction. Remember that 2,000 amphibian species are already on the verge of extinction: be part of the solution!
Recommended Reading
Please read this excellent article on climate change by Vice President Al Gore that appeared in the New York Times November 9th, 2008.
Learn about other threats to frogs
Habitat Destruction
Chytridiomycosis & other infectious diseases
Pollution & Pesticides
Invasive Species
Over-Harvesting
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Climate Change