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Surprise CO2 rise may speed up global warming
By Michael McCarthy, Environment Editor

11 October 2004

The rate at which global warming gases are accumulating in the atmosphere
has taken a sharp leap upwards, leading to fears that the devastating
effects of climate change may hit the world even sooner than has been

Atmospheric levels of carbon dioxide (CO2 ), the principal greenhouse gas,
have made a sudden jump that cannot be explained by any corresponding jump
in terrestrial emissions of CO2 from power stations and motor vehicles -
because there has been none.

Some scientists think instead that the abrupt speed-up may be evidence of
the long-feared climate change "feedback" mechanism, by which global warming
causes alterations to the earth's natural systems and then, in turn, causes
the warming to increase even more rapidly than before.

Such a development would mean the worldwide droughts, agricultural failure,
sea-level rise, increased weather turbulence and flooding all predicted as
consequences of climate change would arrive on much shorter time-scales than
present scenarios suggest, and the world would have much less time to
co-ordinate its response.

Only last month, Tony Blair expressed anxiety that global warming's dire
effects would arrive not just in his children's lifetime, but in his own,
and would "radically alter human existence".

The feedback phenomenon has already been predicted in the supercomputer
models of the global climate on which the current forecasts of warming are
based. A key aspect is the weakening, caused by the warming itself, of the
earth's ability to remove huge amounts of CO2 from the atmosphere by
absorbing it annually in its forests and oceans, in the so-called carbon
cycle. (The forests and oceans are referred to as carbon "sinks".)

Hitherto, however, that weakening has been put decades into the future.

The possibility that it may be occurring now is suggested in the long run of
atmospheric CO2 measurements that have been made since 1958 at the
observatory on the top of Mauna Loa, an 11,000ft volcano in Hawaii, by the
American physicist Charles Keeling, from the University of California at San

When he began, Dr Keeling, who is still in charge of the project and who
might be said to be the Grand Old Man of CO2 , found the amount of the gas
present in the atmosphere to be 315 parts per million by volume (ppm);
today, after the remorseless increase in emissions from power stations and
motor vehicles over the past four and a half decades, the figure stands at

This growth is what most scientists believe is causing the earth's
atmosphere to warm up, as the increasing CO2 retains more and more of the
sun's heat in the atmosphere, like the panes of a greenhouse.

But the worry now is not merely the swelling volume of CO2 but the sudden
leap in its increase rate. Across all 46 years of Dr Keeling's measurements,
the average annual CO2 rise has been 1.3ppm, although in recent decades it
has gone up to about 1.6ppm.

There have been several peaks, all associated with El Niņo, the disruption
of the atmosphere-ocean system in the tropical Pacific Ocean that causes
changes to global weather patterns. In 1988, for example, the annual
increase was 2.45ppm; in 1998, 2.74ppm; both were El Niņo years.

Throughout the series those peaks have been followed by troughs, and there
has been no annual increase in CO2 above 2ppm that has been sustained for
more than a year. Until now.

>From 2001 to 2002, the increase was 2.08ppm (from 371.02 to 373.10); and
from 2002 to 2003 the increase was 2.54ppm (from 373.10 to 375.64). Neither
of these were El Niņo years, and there has been no sudden leap in emissions.

The greater-than-two rise is also visible in two separate sets of CO2
measurements made by America's National Oceanic and Atmospheric
Administration, at Mauna Loa and other stations around the world.

At the weekend, Dr Keeling told The Independent the rise was real and
worrying as it might indeed represent the beginnings of a feedback.

He said it might be associated with the Southern Oscillation, a pattern of
high and low atmospheric pressure previously always associated with El
Niņos, or it might be something new.

"The rise in the annual rate of CO2 increase to above two parts per million
for two consecutive years is a real phenomenon," Dr Keeling said.

"It is possible this is merely a reflection of the Southern Oscillation,
like previous peaks in the rate, but it is possible it is the beginning of a
natural process unprecedented in records.

"This could be a decoupling of the Southern Oscillation from El Niņo events,
which itself could be caused by increased CO2 in the atmosphere; or it could
be a weakening of the earth's carbon sinks. It is a cause for concern."

Leading British scientists and environmentalists agree. "If this is a rate
change [in the CO2 rise], of course it will be very significant," said Dr
Piers Forster of the meteorology department of the University of Reading.
"It will be of enormous concern, because it will imply that all our global
warming predictions for the next 100 years or so will have to be redone. If
the higher rate of increase continues, things will get very much worse. It
will makes our predicament even more catastrophic."

Tom Burke, a former government adviser on green issues who is now an
academic and environmental adviser to business, said: "This series of CO2
measurements is the world's climate clock, and it looks as if it may be
ticking faster," 

"That means we are running out of time to stabilise the climate. Governments
and business will both have to invest dramatically more if we are to avoid
the global warming catastrophe that Tony Blair has warned against."

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