Vanishing Wildlife on a Warming Planet

Joseph Stewart, University of California, Santa Cruz.

The sun is rising on Donner Summit. The air in California’s Sierra Nevada mountains is cold and still. It’s eerily quiet. I’m waiting — listening for the song of the American pika — and growing concerned that pikas here might have gone the way of the glaciers. When I finally hear a staccato series of chirps echo from the crags above, I breathe a sigh of relief. Thank goodness. They are still here.

Pikas — the real-life inspiration behind Pikachu — are audacious little members of the rabbit family. Residents of high mountain peaks, they spend their summers busily collecting plants, which they store away for winter consumption. With their thick coat of fur and furnace-like metabolism, they are well adapted for winter survival under the snow. But these same adaptations make them especially vulnerable to summer heat.

When temperatures become too hot, pikas are forced to stay below ground to avoid overheating. As a result, pikas at warmer sites are not able to collect enough food to survive. That’s what is happening at Donner Summit. Rising temperatures are causing the pikas to starve before they can reproduce. The animal’s numbers at the site have plummeted. Dozens of other populations on mountains throughout the American West have already succumbed, vanishing forever.

Vanishing Iconic Species

The pika’s story is by no means unique. Today, several other species have already been driven to extinction by global warming — and they are just the beginning. Our best estimate is that this century over a million species, 16 percent of all species on earth, will be vulnerable to extinction from climate change. While polar bears have received a generous share of media headlines for their vulnerability, many other species have gotten far less attention. Their ranks include bighorn sheep, pronghorn antelope, tigers, honeycreepers, sea turtles, narwhals, walruses, penguins and salmon.

As the planet warms, species are disappearing from hotter and drier climates. Recent studies show that the new generation of forest trees such as oaks and pines are shifting to higher elevations. Forests throughout the American West are experiencing catastrophic tree death in response to historically unprecedented drought. In many cases, entire ecosystems are threatened. Coral reefs, for example, are already suffering massive die-backs in response to increased ocean temperature.

There’s a precedent for this extinction crisis, although when it happened before, we humans had not yet arrived. More than 250 million years ago, volcanoes in Siberia released massive amounts of carbon dioxide, which warmed the climate and acidified the ocean. Warming caused the oceans to release methane, which led to more warming. The result was an 8°C rise in global temperature and extinction of over 70 percent of all species on the planet.

It took the earth 10 million years to recover.

Scientists refer to that episode in earth’s history as “the Great Dying.” That’s a scary example to think about, but it’s the road we are headed down today, this time because of fossil fuel pollution.

We Can Save a Million Species

As I descend from the rocky habitat at Donner Summit, I think about the pikas’ future at this place. How much longer will they be able to hold out? During my research over the past several years, I have seen pikas disappear from lower elevation sites across California. I wonder whether my children will have to travel much farther north, to much cooler places, to watch pikas collect their wildflower bouquets. And what about all the other animals — the tropical birds, the butterflies and coral-reef fishes, and mammals — we appreciate today?

Our decisions today will have staggering consequences for over a million species. If we choose to continue burning fossil fuels unabated, the best evidence indicates that by the end of this century, about 1.4 million species will be headed toward early extinction. If, on the other hand, we make some significant choices, if we vote for politicians who take climate change seriously, and we are able to limit global warming, we can save many of these species from extinction. But the clock is running out on preventing global catastrophe. We need leaders in Washington who will take bold action now.

Joseph Stewart is a Ph.D. candidate and conservation biologist at University of California, Santa Cruz. Find him online at

Residents of mountain peaks, American pikas spend their summer collecting and storing plants to eat during cold winters under the snow. Global warming is causing pikas to disappear from sites where they were once common.