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Scientists:
Climate Change Could Drive Mass Extinctions
Evidence points to mass extinction
The Scotsman (U.K.), June 18, 2003
The worst mass extinction
in the history of the planet could be
replicated in as little as a century if global warming continues,
according to new evidence.
Researchers at Bristol
University have discovered that a six-degree
increase in the global temperature was enough to annihilate up
to
95 per cent of species which were alive on Earth at the end of
the
Permian period, 251 million years ago.
Up to six degrees of
warming is now predicted for the next century
by United Nations scientists from the Intergovernmental Panel
on
Climate Change (IPCC) if nothing is done about emissions of the
greenhouse gases, principally carbon dioxide, which cause global
warming.
The end-Permian mass
extinction is now thought to have been
caused by gigantic volcanic eruptions, which triggered a
"runaway greenhouse effect" and nearly put an end to
life
on Earth. Conditions in what geologists have termed this
"post-apocalyptic greenhouse" were so severe that only
one
large land animal was left alive, and it took 100 million
years for species diversity to return to former levels.
The new finding is
revealed in a book by Professor Michael
Benton, the head of Earth sciences at Bristol University.
Prof Benton said: "The
end-Permian crisis nearly marked
the end of life. It's estimated that fewer than one in
ten species survived.
"Geologists are
only now coming to appreciate the
severity of this global catastrophe and to understand
how and why so many species died out so quickly."
Tropical latitudes
were the first areas of the Earth
to feel the effect of the warming, and loss of species
diversity spread out from there.
Reduction of vegetation,
soil erosion and the effects
of massively increased rainfall wiped out the lush diverse
habitats of the tropics, which would today lead to the
loss of animals such as hippos, elephants and all of the
primates, according to Prof Benton.
He added: "The
end-Permian extinction event is a good
model for what might happen in the future because
it was fairly non-specific.
"The sequence
of what happened then is different from today
because then the carbon dioxide came from massive volcanic
eruptions, whereas today it is coming from industrial activity.
However, it doesn't matter where this gas comes from;
the fact is that if it is pumped into the atmosphere
in high volumes, then that gives us the greenhouse effect
and leads to the warming with all the other consequences."
Modern predictions
of the apocalyptic consequences of
global warming and climate change due to increases in
carbon dioxide first began to circulate in the early 1980s.
Carbon dioxide is,
like oxygen, translucent to sunlight
but opaque to infra-red radiation. After the sun's rays
have warmed the Earth and sea, the heat produced can
therefore not be re-radiated back into space.
When the industrial
revolution began about 200 years ago,
there were roughly 280 parts per million (ppm) of carbon
dioxide in the atmosphere. Today, there are 350ppm.
More carbon dioxide
is being pumped into the atmosphere
as the human population grows and turns to heavy industry,
and less is being removed by the rest of nature because,
possibly due to human activity, global vegetation which
removes the damaging gas is in retreat.
In the mid-1980s, scientists
first started to predict
that temperatures would increase somewhere in the order
of between four and six degrees by 2080. Sea levels were
also predicted to rise 20cm by 2030, and 45cm by 2070.
In the light of modern
records, these estimates were a
little overstated. Dr Ian Brown, a senior researcher with
the Tyndall Climate Research Centre at the University of
East Anglia, said: "More or less every year now we have
a temperature which is higher than the previous year and
the Met Office has predicted this year that there is a
50 per cent chance it will be the warmest on record.
"Each year is
now pretty much an exceptional one by
previous standards.
"Sea-level rise
is more complicated because we have
a shorter record. At the moment, in global terms,
it is probably in the order of about one and a half
millimetres per year.
"By the end of
the century, the rise in sea level
could then be a lot more than five or even ten centimetres.
Certainly in the past
two decades we have now recorded
rises in sea levels in the region of one or two millimetres
a year which are measured by tide gauges at various sites.
"These instruments
are quite precise and show that
predictions of the consequences of global warming are
certainly observable."
He added: "Much
land has in the past been reclaimed from
the sea, such as in the Forth estuary, and those areas
are now looking increasingly vulnerable."
Climate experts and
environmentalists said yesterday
they were appalled that a disaster of such magnitude
could be repeated within this century because of human
activities.
Mark Lynas, an author
who has written extensively on
global warming and recently travelled around the world
cataloguing impacts of climate change, said the findings
must be a wake-up call for politicians and citizens alike.
"This is a global
emergency," he said. "We are heading
for disaster and yet the world is still on fossil fuel
autopilot. There needs to be an immediate phase-out of
coal, oil and gas, and a phase-in of clean energy sources.
"People can no
longer ignore this looming catastrophe."
