May 15, 2012
Almost One Tenth Of Western Hemisphere Mammals In Danger From Climate Change
A new study led by Carrie Schloss, an analyst in environmental and forest sciences at the University of Washington, finds that nine percent of the Western Hemisphere's mammals, and nearly forty percent in particular regions, will fall victim to the changing climate. Some mammals are merely too slow to escape climate change in their natural habitats and are unable to move into different areas. The study seeks to understand if the mammals can actually adapt to these conditions by moving or not.
Scientists have noted areas for the past ten years that will be able to accommodate the animals in the event that their natural habitats become threatening or uninhabitable. The University of Washington is releasing the paper on the week of May 14 on the online journal Proceedings of the National Academy of Sciences.
The study focused on 493 species of mammals, including a shrew as small as a dime and a moose weighing in at 1,800 pounds. The only dispersing element considered in the study was climate change.
Schloss stated, "We underestimate the vulnerability of mammals to climate change when we look at projections of areas with suitable climate but we don't also include the ability of mammals to move, or disperse, to the new areas.”
“Indeed, more than half of the species scientists have in the past projected could expand their ranges in the face of climate change will, instead, see their ranges contract because the animals won't be able to expand into new areas fast enough,” stated co-author Josh Lawler, UW associate professor of environmental and forest sciences.
In order to determine the rate at which a species must move into different areas, UW researchers used earlier works by Lawler, which display certain species and the areas they need to survive. The works also include ten global climate models that give the rate at which a climate may decline, and a scenario established by the UN Intergovernmental Panel on Climate Change that demonstrates the effects of mid-high greenhouse gas emissions on these climates. With this information, along with the assumed timeframe of movement of one generation, researchers looked at certain species to ascertain information about their survival.
Factors including size and reproduction rates would influence the rate at which they traveled. For example, a small mouse in one generation cannot move far, but with its quick reproduction rates, many mice would be able to move more quickly than creatures that reproduce and mature at a slower rate.
According to Schloss, primates in the Western Hemisphere, for instance, have a slower dispersion rate because they mature within several years and this makes them appear more susceptible to climate change. In addition to this, species in tropical areas are not able to move as quickly into new territories as mammals in mountainous regions, where they simply move to a better elevation for their preferred climates. Not only is it more difficult for tropical creatures to reach a suitable area, but these areas are likely to diminish in the future.
“Those factors mean that nearly all the hemisphere's primates will experience severe reductions in their ranges,” stated Schloss, “on average about 75 percent. At the same time species with high dispersal rates that face slower-paced climate change are expected to expand their ranges.”
Lawler stated, "Our figures are a fairly conservative — even optimistic — view of what could happen because our approach assumes that animals always go in the direction needed to avoid climate change and at the maximum rate possible for them." He also stated, “The researchers were also conservative in taking into account human-made obstacles such as cities and crop lands that animals encounter.”
Researchers used a formula developed prior to the study to understand how humans affect travel patterns of animals. The formula of "average human influence" focuses on areas that might cause animals to encounter high amounts of human development and technologies; however, it does not consider the necessity of an animal to go around and completely avoid human settlements.
Lawler stated, "I think it's important to point out that in the past when climates have changed — between glacial and interglacial periods when species ranges contracted and expanded — the landscape wasn't covered with agricultural fields, four-lane highways and parking lots, so species could move much more freely across the landscape.”
"Conservation planners could help some species keep pace with climate change by focusing on connectivity — on linking together areas that could serve as pathways to new territories, particularly where animals will encounter human-land development," stated Schloss. "For species unable to keep pace, reducing non-climate-related stressors could help make populations more resilient, but ultimately reducing emissions, and therefore reducing the pace of climate change, may be the only certain method to make sure species are able to keep pace with climate change."