Global Warming: Already Past the "Tipping Point"
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Global Warming: Already Past the "Tipping Point"
Via NY Transfer News Collective * All the News that Doesn't Fit
The Independent - Feb 11, 2006
http://news.independent.co.uk/environment/article344690.ece
Global warming: passing the 'tipping point'
Our special investigation reveals that critical rise in world
temperatures is now unavoidable
By Michael McCarthy, Environment Editor
A crucial global warming "tipping point" for the Earth, highlighted
only last week by the British Government, has already been passed,
with devastating consequences.
Research commissioned by The Independent reveals that the accumulation
of greenhouse gases in the atmosphere has now crossed a threshold, set
down by scientists from around the world at a conference in Britain
last year, beyond which really dangerous climate change is likely to
be unstoppable.
The implication is that some of global warming's worst predicted
effects, from destruction of ecosystems to increased hunger and water
shortages for billions of people, cannot now be avoided, whatever we
do. It gives considerable force to the contention by the green guru
Professor James Lovelock, put forward last month in The Independent,
that climate change is now past the point of no return.
The danger point we are now firmly on course for is a rise in global
mean temperatures to 2 degrees [Celsius, or almost 4 degrees F for the
entire planet] above the level before the Industrial Revolution in the
late 18th century.
At the moment, global mean temperatures have risen to about 0.6
degrees above the pre-industrial era - and worrying signs of climate
change, such as the rapid melting of the Arctic ice in summer, are
already increasingly evident. But a rise to 2 degrees would be far
more serious.
By that point it is likely that the Greenland ice sheet will already
have begun irreversible melting, threatening the world with a
sea-level rise of several metres [some 20 feet! -HB]
Agricultural yields will have started to fall, not only in Africa but
also in Europe, the US and Russia, putting up to 200 million more
people at risk from hunger, and up to 2.8 billion additional people at
risk of water shortages for both drinking and irrigation. The
Government's conference on Avoiding Dangerous Climate Change, held at
the UK Met Office in Exeter a year ago, highlighted a clear threshold
in the accumulation of greenhouse gases such as carbon dioxide (CO2)
in the atmosphere, which should not be surpassed if the 2 degree point
was to be avoided with "relatively high certainty".
This was for the concentration of CO2 and other gases such as methane
and nitrous oxide, taken together in their global warming effect, to
stay below 400ppm (parts per million) in CO2 terms - or in the jargon,
the "equivalent concentration" of CO2 should remain below that level.
The warning was highlighted in the official report of the Exeter
conference, published last week. However, an investigation by The
Independent has established that the CO2 equivalent concentration,
largely unnoticed by the scientific and political communities, has now
risen beyond this threshold.
This number is not a familiar one even among climate researchers, and
is not readily available. For example, when we put the question to a
very senior climate scientist, he said: "I would think it's definitely
over 400 - probably about 420." So we asked one of the world's leading
experts on the effects of greenhouse gases on climate, Professor Keith
Shine, head of the meteorology department at the University of
Reading, to calculate it precisely. Using the latest available figures
(for 2004), his calculations show the equivalent concentration of C02,
taking in the effects of methane and nitrous oxide at 2004 levels, is
now 425ppm. This is made up of CO2 itself, at 379ppm; the global
warming effect of the methane in the atmosphere, equivalent to another
40ppm of CO2; and the effect of nitrous oxide, equivalent to another
6ppm of CO2.
The tipping point warned about last week by the Government is already behind
us.
"The passing of this threshold is of the most enormous significance,"
said Tom Burke, a former government adviser on the green issues, now
visiting professor at Imperial College London. "It means we have
actually entered a new era - the era of dangerous climate change. We
have passed the point where we can be confident of staying below the 2
degree rise set as the threshold for danger. What this tells us is
that we have already reached the point where our children can no
longer count on a safe climate."
The scientist who chaired the Exeter conference, Dennis Tirpak, head
of the climate change unit of the OECD in Paris, was even more direct.
He said: "This means we will hit 2 degrees [as a global mean
temperature rise]."
Professor Burke added: "We have very little time to act now.
Governments must stop talking and start spending. We already have the
technology to allow us to meet our growing need for energy while
keeping a stable climate. We must deploy it now. Doing so will cost
less than the Iraq war so we know we can afford it."
The 400ppm threshold is based on a paper given at Exeter by Malte
Meinhausen of the Swiss Federal Institute of Technology. Dr Meinhausen
reviewed a dozen studies of the probability of exceeding the 2 degrees
threshold at different CO2 equivalent levels. Taken together they show
that only by remaining [under] 400 is there a very high chance of not
doing so.
Some scientists have been reluctant to talk about the overall global
warming effect of all the greenhouses gases taken together, because
there is another consideration - the fact that the "aerosol", or band
of dust in the atmosphere from industrial pollution, actually reduces
the warming.
As Professor Shine stresses, there is enormous uncertainty about the
degree to which this is happening, so making calculation of the
overall warming effect problematic. However, as James Lovelock points
out - and Professor Shine and other scientists accept - in the event
of an industrial downturn, the aerosol could fall out of the
atmosphere in a matter of weeks, and then the effect of all the
greenhouse gases taken together would suddenly be fully felt.
[And no, "inevitable" does not mean we have an excuse to do nothing;
it's now a matter of whether things get seriously bad, on the one
hand, or far worse, on the other hand. Time for damage control
to avoid "far worse" for us and our children -HB]
*
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