INFOTERRA: News: Minor Shifts In Temperature Have Major Habitat Effects
http://www.latimes.com/news/science/la-sci-species2jan02,0,6033999.story?coll=la%2Dnews%2Dscience
Los Angeles Times:
January 2, 2003
THE NATION
Minute Shift in Temperature Has Had a Major Effect on Earth, Studies Show
Species are migrating northward because of 1-degree increase in last
100 years, data reveal. It also has sped up spring flowering, egg
hatching.
By Usha Lee McFarling, Times Staff Writer
Gradual warming over the last 100 years has forced a global movement of
animals and plants northward, and it has sped up such perennial spring
activities as flowering and egg hatching across the globe -- two signals
that the Earth and its denizens are dramatically responding to a minute
shift in temperature, according to two studies published today.
One study showed that animals have shifted north an average of nearly four
miles per decade. Another study showed that animals are migrating,
hatching eggs and bearing young an average of five days earlier than they
did at the start of the 20th century, when the average global temperature
was 1 degree cooler.
That 1 degree, according to the studies, has left "climatic fingerprints"
-- pushing dozens of butterfly and songbird species into new territories,
prompting birds and frogs to lay eggs earlier and causing tree lines to
march up mountain slopes.
In some cases, the shifts have been dramatic. The common murre, an Arctic
seabird, breeds 24 days earlier than it did decades ago. And some
checker-spot butterflies shifted their range northward by nearly 60 miles
in the last century.
Although many individual shifts in timing and range have been reported by
field biologists, the studies published in today's issue of Nature are the
first to establish that a variety of organisms in myriad habitats are
responding in similar ways to climatic change.
"There is a consistent signal," said Terry L. Root, a biologist at
Stanford University and lead author of one report. "Animals and plants are
being strongly affected by the warming of the globe."
Root said she was surprised that the two Nature studies were able to
detect the effect. She said she thought the increased temperature was too
small to cause widespread change. Root also said she expected that any
damaging effects of climatic change would be unnoticeable amid the
enormous habitat destruction in modern times caused by development,
pollution and other human activities.
"It was really quite a shock, given such a small temperature change," she
said.
Many scientists have debated whether plants and wildlife have been widely
affected by climatic change. Some have argued that no widespread response
has occurred and that a few examples of animals changing the timing of
their migration or reproduction have been used by environmental groups to
overstate the dangers of global warming.
The new studies attempt to override such criticism by analyzing thousands
of reports of biological change and correlating them with climatic change.
"People said there wasn't a quantitative analysis and it was just
storytelling," said University of Texas biologist Camille Parmesan, who
led the other Nature study. "This is the first hard-core, quantitative
analysis."
The changes are not necessarily bad for all species. The earlier hatching
of eggs gives some bird species a chance to lay two clutches of eggs per
summer instead of one, Root said. With less frost in late spring and early
fall, the growing season of many plants has been extended; crop yields are
also up.
But the scientists are concerned that warming will harm some species,
particularly those already at risk. The extinction of the golden toad from
the cloud forests of Costa Rica has been linked by some scientists to heat
stress, Root said. And chicks of the jewel-colored quetzal bird in the
same forest are now being preyed upon by toucans that moved to higher
elevations in the forest as temperatures warmed, she said.
Ecosystems could also be at risk, she added, if insects mature too late to
pollinate plants that now flower earlier. The earlier migration of wood
warblers is leaving behind spruce trees full of spruce budworm
caterpillars, which devastate the trees and leave the timber damaged.
"If we've had so much change with just one degree, think of how much we
will have with 10 degrees," Root said, referring to projections by the
Intergovernmental Panel on Climate Change on how high temperatures could
rise in the next 100 years. "In my opinion, we're sitting at the edge of a
mass extinction."
But such worst-case scenarios underestimate the ability of biological
entities to adapt, some experts say. In a report written for the George C.
Marshall Institute, Lenny Bernstein, an expert on the social and economic
effect of climatic change, said some "marginal species" will become
extinct. He added, however, that plants and animals have always faced
climatic changes and that they often have survived. Future human
intervention could help increase survival rates, he said.
Although the new studies do not address the cause of the recent warming,
most scientists agree it is due to a mix of human and natural factors. An
increasing number of scientists say that the warming is occurring at a
rate unprecedented in the recent geological past and that it will be
peppered by more extreme events, including heat waves, droughts, storms
and floods.
"It's not just the gradual warming that impacts individuals, it's these
extreme events," Parmesan said.
Convinced that wild animals and plants will need more room if warming
continues, Root and Parmesan advocate including climatic change
projections into long-range planning for wildlife management. Preserves
may offer more options for survival if they run in a north-south
direction, contain elevation gains or are connected to neighboring
reserves, the scientists said.
"Since we can't count on climate being stable," Parmesan said, "you need
to give the organisms a chance to go through some unstable periods."
Copyright 2003 Los Angeles Times
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http://news.bbc.co.uk/2/hi/science/nature/2617139.stm
Wednesday, 1 January, 2003, 22:36 GMT
Wildlife Seeks Cooler Climes
Species are on the move, say scientists
By Alex Kirby
BBC News Online environment correspondent
Two groups of US biologists say they have detected a consistent pattern of
response by wild species to warmer temperatures.
They say this is evidence that climate change is affecting living systems,
as climatologists have predicted.
Many species are forsaking their ranges to find cooler or higher habitats.
And several regular springtime events are now happening earlier than they
did a few decades ago.
The biologists' work is reported in the journal Nature.
Camille Parmesan, of the University of Texas at Austin, and colleagues
conducted a "meta-analysis" of studies of more than 1,700 species.
The balance of evidence from these studies strongly suggests that a
significant impact of global warming is already discernible in animal and
plant populations
They say there have been "significant" moves in range averaging 6.1 km
(3.8 miles) per decade towards the poles, or metres per decade upwards.
Spring events, such as the arrival of migrant species and the laying of
eggs, have advanced by 2.3 days per decade.
Unconvinced
The authors note the difficulties experienced by the Intergovernmental
Panel on Climate Change (IPCC) in assessing how far recent observed
changes in natural biological systems have been attributable to climate
change.
They write: "Differences of opinion among disciplines can stem naturally
from whether the principal motivation is to assess the magnitude of
immediate impacts or of long-term trajectories.
"Most field biologists are convinced that they are already seeing
important biological impacts of climate change. However, they have
encountered difficulty in convincing other academic disciplines,
policy-makers and the general public."
The picture that emerges from their study, they argue, is persuasive in
the round, even though individual species may not show a marked response
to warming temperatures.
They write: "The test for a globally coherent climate fingerprint does not
require that any single species show a climate change impact with 100%
certitude.
"Rather, it seeks some defined level of confidence in a climate change
signal on a global scale."
In the second study Terry Root of Stanford University, California, and
colleagues also report a temperature-related fingerprint in the behaviour
of a range of species.
They found the changes were most marked at high latitudes and high
altitudes, where the largest temperature changes are predicted.
Their meta-analysis included information on species and global warming
from 143 separate studies.
'Significant impact'
The authors say: "These analyses reveal a consistent temperature-related
shift, or 'fingerprint', in species ranging from molluscs to mammals and
from grasses to trees...the balance of evidence from these studies
strongly suggests that a significant impact of global warming is already
discernible in animal and plant populations.
"The synergism of rapid temperature rise and other stresses, in particular
habitat destruction, could easily disrupt the connectedness among species
and lead to a reformulation of species communities...and to numerous
extirpations and possibly extinctions."
Because they were looking for trends, the authors say, they excluded
studies examining climatic cycles such as the North Atlantic Oscillation
and the El Nino cycle in the Pacific west of Chile.
Some scientists continue to maintain that climate change, if it is
happening, is an entirely natural phenomenon which cannot be explained in
terms of human behaviour.
The two Nature studies may not be able to advance discussion of that
argument.
But they do suggest that wildlife is aware of and responding to a new
reality, whatever its causes.
*** NOTICE: In accordance with Title 17 U.S.C. Section 107, this material
is distributed, without profit, for research and educational purposes
only. ***
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