Climate Fear as Carbon Levels Soar
Scientists bewildered by sharp rise of CO2 in atmosphere for second year running
By Paul Brown
October 11, 2004, Guardian/UK
An unexplained and unprecedented rise in carbon dioxide in
the atmosphere two years running has raised fears that the
world may be on the brink of runaway global warming.
Scientists are baffled why the quantity of the main
greenhouse gas has leapt in a two-year period and are
concerned that the Earth's natural systems are no longer able
to absorb as much as in the past.
The findings will be discussed tomorrow by the government's
chief scientist, Dr David King, at the annual Greenpeace
Measurements of CO2 in the atmosphere have been continuous
for almost 50 years at Mauna Loa Observatory, 12,000ft up a
mountain in Hawaii, regarded as far enough away from any
carbon dioxide source to be a reliable measuring point.
In recent decades CO2 increased on average by 1.5 parts per
million (ppm) a year because of the amount of oil, coal and
gas burnt, but has now jumped to more than 2 ppm in 2002 and
Above or below average rises in CO2 levels in the atmosphere
have been explained in the past by natural events.
When the Pacific warms up during El Niño - a disruptive
weather pattern caused by weakening trade winds - the amount
of carbon dioxide rises dramatically because warm oceans emit
CO2 rather than absorb it.
But scientists are puzzled because over the past two years,
when the increases have been 2.08 ppm and 2.54 ppm
respectively, there has been no El Niño.
Charles Keeling, the man who began the observations in 1958
as a young climate scientist, is now 74 and still working in
He said yesterday: "The rise in the annual rate to above two
parts per million for two consecutive years is a real
"It is possible that this is merely a reflection of natural
events like previous peaks in the rate, but it is also
possible that it is the beginning of a natural process
unprecedented in the record."
Analysts stress that it is too early to draw any long-term
But the fear held by some scientists is that the greater than
normal rises in C02 emissions mean that instead of decades to
bring global warming under control we may have only a few
years. At worst, the figures could be the first sign of the
breakdown in the Earth's natural systems for absorbing the
That would herald the so-called "runaway greenhouse effect",
where the planet's soaring temperature becomes impossible to
contain. As the icecaps melt, less sunlight is reflected back
into space from ice and snow, and bare rocks begin to absorb
more heat. This is already happening.
One of the predictions made by climate scientists in the
Intergovernmental Panel on Climate Change is that as the
Earth warms, the absorption of carbon dioxide by vegetation -
known as "carbon sink" - is reduced.
Dr Keeling said since there was no sign of a dramatic
increase in the amount of fossil fuels being burnt in 2002
and 2003, the rise "could be a weakening of the Earth's
carbon sinks, associated with the world warming, as part of a
climate change feedback mechanism. It is a cause for
Tom Burke, visiting professor at Imperial College London, and
a former special adviser to the former Tory environment
minister John Gummer, warned: "We're watching the clock and
the clock is beginning to tick faster, like it seems to
before a bomb goes off."
Peter Cox, head of the Carbon Cycle Group at the Met Office's
Hadley Center for Climate Change, said the increase in carbon
dioxide was not uniform across the globe.
Measurements of CO2 levels in Australia and at the south pole
were slightly lower, he said, so it looked as though
something unusual had occurred in the northern hemisphere.
"My guess is that there were extra forest fires in the
northern hemisphere, and particularly a very hot summer in
Europe," Dr Cox said. "This led to a die-back in vegetation
and an increase in release of carbon from the soil, rather
than more growing plants taking carbon out of the atmosphere,
which is usually the case in summer."
Scientists are have dubbed the two-year CO2 rise the Mauna
Loa anomaly. Dr Cox said one of its most interesting aspects
was that the CO2 rises did not take place in El Niño years.
Previously the only figures that climbed higher than 2 ppm
were El Niño years - 1973, 1988, 1994 and 1998.
The heatwave of last year that is now believed to have
claimed at least 30,000 lives across the world was so out of
the ordinary that many scientists believe it could only have
been caused by global warming.
But Dr Cox, like other scientists, is concerned that too much
might be read into two years' figures. "Five or six years on
the trot would be very difficult to explain," he said.
Dr Piers Forster, senior research fellow of the University of
Reading's Department of Meteorology, said: "If this is a rate
change, of course it will be very significant. It will be of
enormous concern, because it will imply that all our global
warming predictions for the next hundred years or so will
have to be redone."
David J Hofmann of the US National Oceanic and Atmospheric
Administration centre, which also studies CO2, was more
"I don't think an increase of 2 ppm for two years in a row is
highly significant - there are climatic perturbations that
can make this occur," he said. "But the absence of a known
climatic event does make these years unusual.
"Based on those two years alone I would say it was too soon
to say that a new trend has been established, but it warrants
© Guardian Newspapers Limited 2004
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