In 1987, herpetologist Martha Crump witnessed more than 100 golden toads mating inside a puddle of water no larger than a kitchen sink. But the thousands of fertilized eggs left behind were soon dried out and infested with mold. Two years later, she returned to the same site in the Monteverde Cloud Forest Preserve of Costa Rica and found just a single golden toad—the last one that she or anyone else ever saw.
Crump and her colleague Alan Pounds spent the next decade trying to explain what caused the die-off. They concluded that the warming ocean had lifted clouds from Monteverde's ridge tops, reducing the moisture available during the toad's breeding season. The golden toad, they argued, was Costa Rica's first documented casualty of climate change.
I remember that time well because in 1998, I was an amphibian-crazed tropical biologist roaming Monteverde's slopes with rubber boots, a headlamp, and Pounds' field guide to the area. Although the Kyoto treaty had been negotiated the year before, climate hysteria had yet to grip the environmental consciousness. Back then, if you'd asked me what the most pressing threat to wildlife was, I wouldn't have blinked: The world's rainforests were vanishing at a rate of more than 54,000 square miles per year, destroying the most biologically diverse ecosystems on Earth for timber, soybeans, and cattle ranches. Clearly, the answer was habitat destruction.
I've left academia since then and become a journalist covering everything from deadly birds in Australia to the future of the Antarctic Treaty. But when I think back to that question about wildlife, I fall into a bit of a muddle. The magazines, newspapers, and Web sites that pay my salary have little to say about habitat loss these days. Now, being green is all about greenhouse gases: Neighborhood moms are more apt to fret over food miles than felled forests; organic cattle farmers are more interested in offsetting the methane coming from cow burps than pondering squished tadpoles in hoof prints. Even scientists have grown bored with question of habitat loss, tweaking their grant proposals to emphasize the climate angle no matter how tenuous the connection. Saving the Amazon is so 1980s.
Climate change has the potential to displace the most impoverished human populations and bring about food shortages, flooding, and drought. But from the perspective of saving species, it's a MacGuffin: a plot device that may impel the tired conservation narrative forward but is hardly a pragmatic strategy for preserving biodiversity. Today, environmentalists tend to describe forests as little more than "carbon sinks," sucking carbon dioxide from the atmosphere. If you really want to conserve plants and animals, though, that may be their least significant attribute.
To be sure, scientists have demonstrated a connection between species extinction and climate change—but it's hardly as significant as you might think. The most influential study of the subject, which appeared in the prestigious journal Nature in 2004, relies upon a sketchy extrapolation. The researchers claimed that changing weather patterns would commit up to 37 percent of the world's species to extinction by 2050—far more than would go extinct if we continued at the current rate of habitat destruction. But the authors completely ignored the tropics, where most of the world's species live, focusing instead on the temperate and polar ecosystems that will experience the most significant changes in annual temperatures.