http://news.bbc.co.uk/2/hi/science/nature/2617139.stm
Species are on the
move, say scientists
Wednesday, 1 January,
2003, 22:36 GMT
Wildlife seeks cooler climes
By Alex Kirby
BBC News Online environment correspondent
QUOTE:
"The balance of evidence from these studies strongly suggests
that a significant impact of global warming is already
discernible in animal and plant populations"
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.
They say there have
been "significant" moves in range
averaging 6.1 kilometres (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
that 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.
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