by Rod Hughes
The message is clear behind biologist Ana Fonseca’s analyses of the effects of global warming on Costa Rica, one of the most diverse ecosystems in the world:
Come visit before most of it disappears.
The University of Costa Rica scientist calculates that over the next 90 years, 160,000 species of plants and animals will go extinct, including (divers take note) 50% to 82% of the coral reefs. The country has already experienced, since the 1980s, the disappearance of exotic species of frogs from the high mountains here, some of them to be found nowhere else in the world. That was even before projections by scientists that the temperature may rise 3 degrees Celsus in the next nine decades, raising the ocean levels three feet.
While amphibians such as frogs are notoriously temperature-sensitive, one does not think of reptiles as being so delicate. But some of them cannot reproduce if the temperature rises above a certain level, Fonseca reveals. And the reefs are home to certain algae that enable the little coral creatures to breathe and live. Without coral, whose colorful exoskeletons constitute havens for hundreds of fish species, valuable barriers to hurricanes disappear. If the present temperature of 28 degrees Celsus rises another degree, the seas turn acidic and those algae are gone and so are the reefs, says Fonseca.
Carlos Drews of the World Nature Fund’s marine program notes that the case of the reptiles is unique during global warming. If the nest temperature rises above 29.4 degrees turtles will produce only females and crocodiles only males, hardly a formula to propagate the species. Bit it is worse if the nest temperature rises to 30 degrees: the eggs grow hard and will not hatch.
In the cloud-shrouded mountains of Monteverde, a nature-lover’s paradise, the Golden Toad and Harlequin Frog have already succumbed to a fungus previously unknown because the plague could not previously survive the cool temperatures of the cloud forest. UCR scientists say 21 species of amphibians are already gone forever. And temperature increases will disrupt the natural cycle of flowers, trees and other plant life with untold damage to the 167 species of birds resident in the country.
On local Pacific beaches, the leatherback turtle population has already diminished 90% in the past 60 years.
Nor will human beings be unaffected. Tropical diseases such as dengue can be expected to rise.