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.
A more balanced analysis, modeling the plight of the Earth's 8,750 bird species, appeared a few years later in the journal PLOS Biology. Assuming the greatest pace of economic development with little regard for the environment, the study predicted that 1,101 species would be lost over the next century due to habitat loss alone, while just 64 would be lost to climate change alone. Some 800 additional species would disappear under the combined effects of habitat loss and climate change. "Our results," the authors diplomatically wrote, "show notable differences from previous studies."
Don't get me wrong: The loss of every species is a tragedy. But the hip word in conservation these days is triage—in a world with limited resources, you've got to pick out what to save and what to let go extinct. No doubt, some of those 64 bird species are going adapt or migrate with the changing climate, while the rest will likely be on permanent life support no matter how much money we throw at them. Protecting tropical real estate is a lot cheaper and more effective than rebuilding our energy infrastructure. And while climate change remains a legitimate concern for wildlife—particularly on isolated mountaintops and in species-poor polar regions—it does not come close to the immediate, irreparable damage caused by the destruction of habitat. Our ecosystems are not just getting warmer or colder or wetter or drier. They're disappearing.
Even if we consider the impact of environmental degradation on humanity, deforestation has a more significant and immediate impact on local weather, water availability, water quality, and soil erosion than does global climate change from greenhouse gases. The roots of trees and native brush hold loose, nutrient-rich topsoils together, slowing erosion and absorbing precipitation. You can see the impact of habitat loss on local climate by poking a stick into the parched soils of the Brazilian cerrado or wandering along the boundary of the expanding Sahel Desert in Africa. Then there's Cherrapunjee, India, once considered the wettest place on Earth—and now facing climbing temperatures and water shortages as the once lush landscape has been denuded.
Only recently have conservationists begun to grasp what a debacle it was to enact climate change legislation in Europe without first putting in place global deforestation treaties. EU policies promoting a market for biofuels triggered the destruction of Indonesian rain forests in favor of palm plantations. Meanwhile, the forestry industry has argued that their monoculture plantations in Asia, Africa, and South America deserve credit as carbon sinks, but the data show that these biological deserts are actually spewing out carbon dioxide. We don't have federal climate change legislation in place in the United States, but the Obama administration is pushing for a carbon tax in the new budget. Conservationists now have an apparent ally in the White House, so let's tell him to slow down and get those forest protections in place before the carbon-conscious spill any more blood.
As for Crump's golden toads, biologists aren't even certain it was climate that did them in. The International Union for the Conservation of Nature has listed three additional culprits: restricted habitat, airborne pollution, and a fungal pathogen that may well have been spread by human contact. One rigorous but underappreciated study in the journal Science has even made the case that deforestation in Costa Rica's lowlands shares the blame for Monteverde's missing clouds. Back when I roamed those mountains hunting for slimy creatures in the dark, I mostly came back empty-handed. Even so, there was always more wildlife—amphibian or otherwise—in those mountaintop cloud forests than in the sprawling cattle ranches below.