I’m seeing nothing especially new here, but, with that said, some
important concerns do get further confirmation, and some important
new details offered.
For example, a shift of biomes (e.g., forest shift to grassland) has
been a growing concern in recent years, and not one expressed only
within narrow scientific circles. When 60 Minutes interviewed Thomas
Sweatnam a year or more ago, he stated the risk that forests could be
replaced by a new and different biome.
The challenge for snow dependent species such as lynx has also been
noted before. But it’s been scientifically important to put those
issues to the test, and have them confirmed — or not. And the
challenge for the Propertius duskywing butterfly if climate change
happens too fast for survival of oak trees is a new detail in the
realm of broken synchrony between one species and another.
“Lynx is one species that is vulnerable, but the potential impacts of
climate change on entire ecosystems are even more alarming.”
Public release date: 4-Aug-2008
Ecological Society of America
Contact: Christine Buckley
Climate change and species distributions
How changing temperatures push living things to the edge
Scientists have long pointed to physical changes in the Earth and its
atmosphere, such as melting polar ice caps, sea level rise and
violent storms, as indicators of global climate change. But changes
in climate can wreak havoc in more subtle ways, such as the loss of
habitat for plant and animal species. In a series of talks at the
Ecological Society of America (ESA) 93rd Annual Meeting, climate
change scientists will discuss how temperature-induced habitat loss
can spell disaster for many living things.
Climate models project that rising temperatures over time can lead to
an increase in dry, desert-like conditions, which will affect not
only the survivorship of particular species, but also the natural
resources they have adapted to use in their natural environment.
Species are thus forced to move elsewhere to find places to live and
food to eat.
“Impacts on individual species indicate wider changes at the biome
level that will potentially change conditions for many plant and
animal species, in addition to ecosystem services to humans,” says
Patrick Gonzalez, a researcher at The Nature Conservancy and a member
of the Intergovernmental Panel on Climate Change (IPCC).
One species whose habitat may be in danger is the Canada lynx, which
is listed as threatened in the United States. The feline’s main prey,
the snowshoe hare, lives in deep snow cover in boreal forest. Because
they rely so heavily on hares for food, lynx are adapted to live in
areas with snow cover at least four months out of the year. The cats
are so specialized to life on snow that their paws are much wider
than is required to support their weight; the large paws help them
stalk hares over deep snow without falling in.
Gonzalez, who has worked with USDA Forest Service scientists to
analyze lynx habitat, projects that a temperature increase of 2.5 to
4 degrees Celsius in the coming century across the U.S. and
Canada-the range of warming under the scenarios reported by the
IPCC-may diminish snow cover suitable for lynx by 10 to 20 percent
and reduce boreal forest cover by half in the contiguous U.S.
Together, these changes could shift lynx habitat northward and
decrease the area of habitat in the lower 48 states by two-thirds.
This potentially extensive loss of habitat signals serious changes in
boreal and alpine ecosystems, says Gonzalez.
Climate change can result in animals and plants migrating northward
to escape the heat, but in many cases suitable habitat becomes scarce
or unavailable farther away from the species’ natural range. The
Propertius duskywing butterfly lives throughout the West Coast of the
U.S., and during its caterpillar stage is specialized to live on oak
trees. Shannon Pelini, a graduate student at the University of Notre
Dame, conducted experiments revealing that warmer temperatures
increased the survivorship and body size of caterpillars in its most
northern habitats. A lack of oak trees in more northern climes,
however, would preclude them from moving further north. The range
shift of oak trees will happen much slower than the shift for the
butterflies, leading to a contracted range, says Pelini.
As if the direct effects of rising temperatures weren’t enough,
climate change also has impacts that could make climate patterns less
consistent over time. Michael Notaro, a scientist at the University
of Wisconsin-Madison, used climate data from the past century to
model vegetation changes over time. He found that large variability
in climate causes an increasing number and intensity of fires and
droughts, as well as extreme weather events that could kill
long-lived trees and allow short-lived grasses to colonize the
leftover space. His models predict that year-to-year variability in
precipitation and temperature reduces the Earth’s total vegetation
cover, expanding its relative grass cover and diminishing its
relative tree cover.
“The central U.S. is characterized by an ecotone that’s the
intersection of forest in the East and grassland in the West,” says
Notaro. “The border between these ecosystems is largely determined by
climate variability and it is likely that climate change will shift
the location of this and other ecological boundaries worldwide.”
Gonzalez agrees that the research results presented at the ESA Annual
Meeting indicate serious vulnerabilities of both individual species
and global biomes to climate change.
“Climate change threatens to alter extensive areas of habitat,” says
Gonzalez. “Lynx is one species that is vulnerable, but the potential
impacts of climate change on entire ecosystems are even more
The researchers will present their results in the following oral sessions:
Shannon Pelini and Patrick Gonzalez – Climate Change: Range and Phenology
Monday, Aug. 4, 1:30-5 p.m. (3 1/2 hours)
Michael Notaro – Climate Change and Plants I
Tuesday, Aug. 5, 8-11:30 a.m. (3 1/2 hours)
For more information about this session and other ESA Annual Meeting
activities, visit http://www.esa.org/milwaukee. The theme of the
meeting is “Enhancing Ecological Thought by Linking Research and
Education.” More than 3,500 scientists are expected to attend.