As Planet Warms, One in Six Species Face Total Extinction: Study

One in six of all animal and plant species on Earth could become extinct from impacts related to climate change if human society does not dramatically reduce its emission of greenhouse gases, according to new research published in the journal Science on Thursday.

Conducted as a meta-analysis of existing research done on the possible impact of climate change on species loss, the new study--titled Accelerating Extinction Risk From Climate Change--found that the range of predicted loss went from no species loss at all (0%) to as much as 54% in extreme scenarios, but that a synthesis of the existing data and new modeling offered a clearer view of what the future may hold.

Mark Urban, professor of ecology at the University of Connecticut and lead author of the new study, says its most worrying findings are not set in stone but should come as a warning to humanity and world leaders that action on climate must come soon if the planet is to maintain its existing biodiversity and ability to support life. Though its conclusions are considered "predictive" and based on various models of what the future may look like, the study warns that as warming continues to increase in the coming decades the rate of extinctions could accelrate rapidly.

"We have the choice," Urban told the New York Times in an interview. "The world can decide where on that curve they want the future Earth to be."

And as Urban writes in the study:

In 1981, [NASA's Dr. James] Hansen and colleagues predicted that the signal of global climate change would soon emerge from the stochastic noise of weather (26). Thirty years later, we are reaching a similar threshold for the effects of climate change on biodiversity. Extinction risks from climate change are expected not only to increase but to accelerate for every degree rise in global temperatures. The signal of climate change-induced extinctions will become increasingly apparent if we do not act now to limit future climate change.

As the Guardianreports:

The study is the most comprehensive look yet at the impact of climate change on biodiversity loss, analysing 131 existing studies on the subject. The stresses on wildlife and their habitats from global warming is in addition to pressures such as deforestation, pollution and overfishing that have already seen the world lose half its animals in the past 40 years. [...]

The study also emphasises that even for the animals and plants that avoid extinction, climate change could bring about substantial changes in their numbers and distribution.

Jamie Carr at the climate unit of the International Union for Conservation of Nature, which compiles the most authoritative list of endangered species worldwide, said: "The loss of one in six species, would be an absolute tragedy, not only because it is sad to lose any part of our rich natural world, but also because biodiversity is fundamental in providing important functions and services, including to humans.

"Such significant changes to biological systems would undoubtedly have knock-on effects, and could potentially result in the collapse of entire systems."

Even as the study arrived at its "dire" 16 percent extinction rate by assessing available research, Professor John J. Wiens, an evolutionary biologist at the University of Arizona, was among experts who told the Times the reality could end up much worse. According to Wiens, the number of extinctions "may well be two to three times higher."

As the Times notes:

Dr. Urban found that the rate of extinctions would not increase steadily, but would accelerate if temperatures rose.

Richard Pearson, a biogeographer at University College London, called the new meta-analysis "an important line in the sand that tells us we know enough to see climate change as a major threat to biodiversity and ecosystems."

But he said that Dr. Urban was likely underestimating the scale of extinctions. The latest generation of climate extinction models are more accurate, Dr. Pearson said: sadly, they also produce more dire estimates.

For his part, Urban seemed most interesting in making sure his research added to that of the broader scientific community which has called on government leaders to do act on climate. As he told the Guardian, "This isn't just doom and gloom. We still have time. Extinctions can take a long time. There are processes that could be important in mediating these effects, for example evolution, but we really need to very quickly start to understand these risks in a much more sophisticated way."