Here's How Many Animals Could Go Extinct Because of Climate Change

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Whether it's a greater abundance of scorching hot temperatures or once in a hundred year storms happening every decade or so, all those lumps of coal, barrels of oil, and deposits of natural gas that humans have burned since the Industrial Revolution are causing quite a lot of havoc for the Earth's climate.

For hundreds of thousands of species, though, our system of economic production is propelling them toward extinction.

Sixteen percent of all know species could go extinct because of climate change, says University of Connecticut ecologist Mark Urban in a new paper published in the journal Science.

That's right: If human greenhouse gas emissions are not reduced, and warming continues along its current trajectory, about one in six species could vanish from the face of the Earth, according to Urban.

"It's hard to even comprehend how much damage these extinctions will inflict upon ecosystems and human communities," Shaye Wolf, climate science director at the Center for Biological Diversity, told VICE News. "It's a sort of very striking and terrifying synthesis of the science to date on what consequences that climate disruption is going to inflict on wildlife."

Already the world has warmed 0.8 degrees Celsius (1.4 degrees Fahrenheit) above preindustrial temperatures. That, according to Urban's analysis, will likely cause 2.8 percent of the Earth's species to go extinct. That number rises to 5.2 percent if warming increases to 2 C (3.6 F), the limit that most scientists agree is necessary to avoid the most catastrophic effects of climate change. At 3 C (5.4 F) the rate increases to 8.5 percent and at 4.3 C (7.7 F) — the warming we'll reach under a "business as usual" scenario where emissions aren't lowered — it reaches 16 percent.

Urban analyzed 131 previously published scientific papers to determine how extinction rates change with increased global temperatures. He found that globally, the extinction rate speeds up the more the planet warms. Averaged across all warming scenarios, which range from the current level of 0.8 C to 4.3 C, the studies predicted that climate change will likely cause about 8 percent of species to go extinct.

"The most important part of this is that with increases in temperature rise in the world, you see this steady upward swing to the extinction risk," Urban told VICE News.

Even brief exposure to temperatures above 78 degrees Fahrenheit can kill the American Pika, a small mammal that inhabits the Western United States and southwestern Canada. Already, because of rising temperatures, it's disappeared from a third of it's habitat in Oregon and Nevada.

"Species' biologies are really intrinsically tuned to the climate," Urban told VICE News. "It's such an important thing when temperatures rise or decline, or when rainfall events occur. When you alter those different variables in different ways you can cause those species to not be able to survive and reproduce anymore."

Related: Over half of Earth's wildlife has been killed in the past 40 years

South America, Australia, and New Zealand face the greatest risks from warmer temperatures, according to the study, with up to 23 percent of species going extinct if warming continues unabated. That could be because those areas are home to high numbers of species that can't live anywhere else, making them more vulnerable to changes in their environment.

"My fear is that the situation is likely worse than the 8 percent extinction risk predicted in this paper," H. Resit Akcakaya, an ecologist at Stony Brook University, told VICE News. "Most of the studies analyzed in this paper are from temperate regions, while most of Earth's biodiversity is, and more of the biological impact will be, in tropical regions."

Several reviews of the impacts of climate change on biodiversity have concluded that humans could be causing the sixth mass extinction in half a billion years.

While Urban's assessment is not nearly as dramatic in its conclusion as those studies, reducing emissions is key to keeping any mass loss of species diversity in check, Urban said.

"We need to start acting now," Urban told VICE News. "We can see the impact of climate change. Now we need to recognize those dangers and do something about it."

Related: Humans may be causing the sixth great extinction in half a billion years

Follow Laura Dattaro on Twitter: @ldattaro

Photo via Flickr