A weekly series by UPI examining the potential human impact on global climate change.
BOULDER, Colo., Jan. 12 (UPI) -- Little research exists linking species extinction to an inability to adapt to climate change. But the available data suggest where the species is located and how resilient it is will be its keys to survival.
A paper published in Nature last week included a prediction that between 15 percent and 37 percent of species in six important ecological regions around the world could become extinct by the year 2050 because they are unable to adapt to global climate change.
The research was a collaboration of 19 scientists promoted by IUCN-The World Conservation Union. The principal authors are from the University of Leeds in the United Kingdom and Conservation International in Washington, D.C.
The case is not clear-cut, however, because individual species react differently to change. Some are more flexible than others. Some would benefit from a warmer world, some would be hurt by it -- perhaps driven to extinction. The research that has looked at specific species offers a broad spectrum of possibility.
If is not difficult to find people who will argue that climate change actually will promote biodiversity. The authors of a George C. Marshall Institute study, "The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere?" make just that case and wrote "the facts do not support claims of mass extinction arising out of climate change."
The study argued that plant and animal species have expanded their ranges in the face of rising temperatures and have "an improved ability to avoid extinction."
True, perhaps, but climate change is not the only threat facing plants and animals. At least as severe a problem is the loss of habitat by the expansion of human agriculture and settlement.
For example, on the macro scale a recent study by Princeton University oceanographer Jorge Sarmiento suggested three-quarters of all biological activity in the oceans is critically dependent on a single ocean circulation pattern in the Southern Hemisphere, where nutrient-rich water rises from the deep and spreads across the seas.
One potential effect of climate change is the disruption of this pattern by an influx of fresh water in the North Atlantic, where this pattern -- called the thermohaline circulation -- originates. Marine organisms account for half of all biological productivity on Earth.
"When we shut off this one pathway in our models, biological productivity in the oceans drops to one-quarter of what it is today," Sarmiento said.
The results suggested that ocean life may be more sensitive to climate change than previously believed because most global warming predictions indicate that major ocean circulation patterns will change.
Along the same idea, climate change could spell the end of the North Atlantic right whale, according to Cornell University ecologists. There are only 300 left and their reproduction is closely tied to food abundance -- plankton -- which is in turn closely associated with these ocean circulation patterns.
The study of specific species and their adaptability to climate is a scattershot business. Biologists don't usually study "climate change," they study bears or mice or coral and how those animals fit into the environment. The most obvious impact of climate on animals is the availability of the food it eats. If the animal's food cannot survive, the animal may not either.
Colleen Cassady St. Clair, a behavioral ecologist at the University of Alberta, said warmer ocean temperatures in the Pacific may be harming reproduction of the tufted puffin. Researchers have tracked the reproductive rates of the puffin for the past two decades. There have been numerous reproductive failures in those years, which the researcher attributed to the puffin's prey -- an anchovy-like fish called the sand lance -- abandoning areas of warm water.
"It appears that these fish leave areas with warm water," St. Clair said. "When this warm water surrounds the breeding colonies, the puffins can't catch fish. The adults then appear to abandon their chicks under these conditions, perhaps so that they can forage farther offshore, and the chicks are left to starve."
The perils of generalizing about the effects of climate change on animals also are visible here. None of the other species that breed in the same region seem to have been adversely impacted by the changes.
The warming that already has occurred has moved the arrival of spring to a couple of weeks earlier in the year in many places in the Northern Hemisphere.
Camille Parmesan, of the University of Texas, Austin, has looked at the impact of this early spring arrival on butterflies. In California, she tracked checkerspot butterflies and found that populations of the insects became extinct in areas where they had previously thrived, and that healthy populations were found considerably north of earlier groups.
Parmesan said because of warmer temperatures, one large population of butterflies had arrived at their spring habitat several weeks early. They were hit with spring snowstorms, events typical of the area but for which the butterflies usually arrived too late. The population survived the first storm, though it was reduced in size, but a second storm wiped it out. After five years, it still had not re-established itself.
Parmesan also studied populations of about 35 different species of butterflies in Europe. She said of the 35 non-migratory species of European butterflies, 63 percent shifted their ranges north by between 20 and 140 miles. Only 3 percent shifted southward.
Survival and expansion for a species can be almost whimsical. Stanford University postdoctoral fellow Jonathon H. Stillman examined the effect of climate change on porcelain crabs, a cold-tolerant species. He found they are more likely to adjust to a warming planet than warm-tolerant crab species.
"This is definitely counterintuitive. You would expect heat-tolerant organisms to be the most resilient to global warming, but it turns out they may have a harder time surviving as their habitat temperatures increase," Stillman said.
Peter Pockley, a correspondent for Nature, reported that on Heard Island in Australia increasing average temperatures have resulted in substantial increases in population among the islands vulnerable cormorants and fur seals.
Johannes Foufopoulos, assistant professor at the University of Michigan School of Natural Resources and Environment, said the impact of current global climate change is not analogous to the past, in which populations of a species would die out on one edge of their habitat range and expand into newly available habitat at the other edge.
"Humankind has fragmented natural habitats to such a degree that many species will not be able to track a warming climate," Foufopoulos said. "There might be buildings, suburban sprawl or miles of roads in the way now."
Foufopoulos said mobile species, such as birds or butterflies, which can colonize new habitats with relative ease stand the best chance of survival as temperatures increase. Sessile species, such as reptiles and amphibians, are at the greatest risk for extinction.
Dan Whipple covers the environment for UPI Science News. E-mail [email protected]