Earth's Defenses against Climate Change 'Beginning to Fail'
Pastor Dale Morgan
Earth's Defenses against Climate Change 'Beginning to Fail'*
Michael McCarthy
Independent UK.
The earth's ability to soak up the gases causing global warming is
beginning to fail because of rising temperatures, in a long-feared sign
of "positive feedback," new research reveals today.
Climate change itself is weakening one of the principal "sinks"
absorbing carbon dioxide - the Southern Ocean around Antarctica - a new
study has found.
As a result, atmospheric CO2 levels may rise faster and bring about
rising temperatures more quickly than previously anticipated.
Stabilizing the CO2 level, which must be done to bring the warming under
control, is likely to become much more difficult, even if the world
community agrees to do it.
The news may give added urgency to the meeting in three weeks' time
between the G8 group of rich nations and the leading developing
countries led by China, at Heiligendamm in Germany, when an attempt will
be made to put together the framework of a new world climate treaty to
succeed the current Kyoto protocol.
"This is a timely warning in advance of Heiligendamm and the G8 that the
climate clock is beginning to tick faster," said the leading
environmentalist Tom Burke, visiting professor at Imperial College London.
"The shift that has been detected in a four-year study by researchers
from the University of East Anglia, the British Antarctic Survey and the
Max-Planck Institute for Biogeochemistry, published in the journal
Science, is one of the most ominous in the development of climate
change. It implies a breach in the planet's own defenses against global
warming.
Human society has hugely benefited from the earth's natural carbon
absorption facility, which means oceans and forests take up roughly half
of the CO2 pumped into the atmosphere, in the so-called carbon cycle.
What is left in the atmosphere is known as the "airborne fraction".
If sinks weakened, the airborne fraction would be likely to get bigger.
Although supercomputer models of the climate have for some time
predicted the weakening of the ocean and terrestrial sinks, no example
of it happening has actually been detected - until now.
Now the research team has found the vast Southern Ocean, which is the
earth's biggest carbon sink, accounting for about 15 per cent of the
total absorption potential, has become effectively CO2-saturated.
The level of the gas it is absorbing has remained static since 1981 -
but in that time the amount emitted has grown by 40 per cent, so it has
stopped keeping pace and much more CO2 is left over to trap the sun's heat.
The effect - revealed by scrutinizing observations of atmospheric CO2
from 40 stations around the world, is thought to have been caused by an
increase in ocean wind speeds. Stormier weather and stronger waves are
churning up the sea and bringing natural CO2 stored there closer to the
surface - which reduces the ability of the surface to absorb the gas
from the air.
The increased winds are believed to be caused by altered atmospheric
temperature regimes produced by two separate processes - the depletion
of the ozone layer over Antarctica by chlorofluorocarbon gases from
aerosol spray cans (now phased out), and global warming.
It is thus a positive feedback - an effect of climate change which
itself makes climate change worse. Some researchers fear that feedbacks
may make global warming happen much faster, and harder to control, than
generally appreciated. The pessimism of scientists such as James
Lovelock is largely based on the fact that most feedbacks in the earth's
system are likely to work against us.
"This is the first unequivocal detection of a carbon sink weakening
because of recent climate change," said the lead author of the study,
Corinne Le Quéré, of the University of East Anglia. "This is serious.
Whenever the world has greatly warmed in the past, the weakening of CO2
sinks has contributed to it."
Professor Chris Rapley, director of the British Antarctic Survey, said:
"Since the beginning of the Industrial Revolution the world's oceans
have absorbed about a quarter of the 500 gigatons [millions of tons] of
carbon emitted by humans. The possibility that in a warmer world the
Southern Ocean is weakening is a cause for concern."
The Government's chief scientific adviser, Sir David King, said: "We
have quite a large number of positive feedbacks to worry about, and this
appears to be another one. But the seriousness of it would depend on if
it was affecting the whole ocean, or merely the Southern Ocean."
In recent years it has become clear that the rate at which CO2 was
accumulating is itself increasing. The level currently stands at about
382 parts per million by volume (ppm), up from 315 ppm in 1958.
In the past decade the rate has jumped from about 1.6ppm annually to
well above 2ppm - a fact which, as The Independent reported in October
2004, may well signal that the earth's absorption ability is shrinking.
Asked if this rate increase could now be linked to weakening sinks, Dr
Le Quéré said: "I think we are just at the border of detecting that."
She added: "All the carbon cycle experts have their eyes on it."
Saturations of the Southern Ocean CO2 sink due to recent climate change,
Le Quéré et al, published this week in Science
(*) Published Independent UK.