Forwarded from Mark
lnp3 at SPAMpanix.com
Fri Jun 9 06:43:16 MDT 2000
Jose G. Perez wrote:
"Maybe the scientists in Britain are different from the American ones.
There is absolutely no agreement in the scientific community that there has
been a significant change towards more extreme weather patterns. But don't
take my word for it. The following is from NOAA:"
The same report ends with these words: "Based on the incomplete evidence
available, the projected change of 2 to 7°F (1-3.5°C) over the next century
would be unprecedented in comparison with the best available records from
the last several thousand years."
Perhaps you didn't read to the end? Bearing in mind that what the NOAA says
about climate change is morally equivalent to health warnings issued by
tobacco companies, I'd say you are falsely comforted. You'd be even less
comforted if instead of quoting the most cuatious, conservative and public
sources, you dug a bit deeper, for instance the National Research Council's
Expert Panel of the U.S. Global Change Research Program announced at a
seminar in Washington on May 11, 2000 that:
"The Panel of experts affirmed the conclusion of the 1995 IPCC report that
global mean surface temperature has warmed rapidly since 1979; and it noted
that the upward temperature trend has continued and accelerated in the
years since the 1995 report went to press. " The report's co-author, John
Wallace, was until 1998 co-director of the NOAA whose reports you keep citing.
If you dig just a little deeper, you'd find even more cause to worry. In
October 1998, The Guardian reported this:
Wave after wave
Hurricane Georges and El Nino are not flukes of nature, argues Mark Maslin.
They are symptoms of rapid climate change - and there are more storms to come
El Nino, Hurricane Georges, floods - all weather events which keep coming
back into the news because of the havoc they they cause. The pattern of
larger, more frequent, and more damaging extreme weather events is exactly
what the scientists studying global warming predicted.
We do not know yet whether Hurricane Georges, which hit the Caribbean and
the Gulf of Mexico last week with devastating force, is the costliest ever
in purely monetary terms. Will it surpass the previous big one, Hurricane
Andrew? In August 1992 Andrew hit the United States and caused damage
estimated at $20 billion. These are, however, not isolated freak storms.
The past 10 years have seen a series of hurricanes successively dubbed the
worst of the century.
Further evidence of a surge in storm activity is provided by the increasing
height of waves. Wave height has been monitored in the North Atlantic since
the early fifties, from light ships, Ocean Weather Stations and more
recently satellites. Between the fifties and nineties the average wave
height has risen from 2.5 metres to 3.5 metres - an increase of 40 per cent.
This intensification of the climate system is not isolated to the North
Atlantic. Results from Dr Julie Cole's group at the University of Colorado
show that the El Nino-southern oscillation is speeding up. This is caused
by the fluctuating balance between warm and cold surface waters, affecting
atmospheric pressure either side of the Pacific. By drilling into the coral
reefs off southern New Guinea, they obtained a 200-year-long continuous
record of the sea surface temperature, beyond all historic records. By
comparing the coral temperature record of the western Pacific with other
proxy records they found that over the past 200 years the frequency of El
Nino events has increased from once every five years to once every 2.8 years.
These are sobering results considering the huge weather disruption and
disasters it causes. Modelling results also suggest that the current
'heightened' state of El Nino can permanently shift weather patterns: for
example, it seems that the drought region in the US could be shifting
Not only have El Nino and wave height been enhanced throughout this
century, but they both contain a sharp rise in the seventies. This is when
the surface global temperature records show the first steep increase -
interpreted as the first sign of global warming. But does this correlation
make global warming the culprit?
The answer is yes, since global warming is constantly putting more energy
into the climate system. This energy must be dissipated both by speeding up
the whole system and by increasing the number and intensity of storms.
We know from the records that during periods of rapid climate change
weather patterns become erratic and the number of storms increase. An
example of this is the Little Ice Age which lasted from the end of the 16th
century to the beginning of the 18th. This period is mainly remembered as
the time when ice fairs were held on the frozen Thames. However, going into
and coming out of the Little Ice Age produced apocalyptic tempests: in
1703, as the climate was finally warming, the worst recorded storm in
Britain killed more than 8,000 people.
Rapid warming thus increases global storminess, creating perfect conditions
for hurricanes. They and their cousins, cyclones and typhoons, form in the
tropics when the sea surface temperature is at least 26C down to 60 metres
below the surface. All it then takes is a further increase of 1C in sea
surface temperature to reduce atmospheric pressure enough to start the
convective cell. It is this rapidly rising air which sucks in air at sea
level and produces the powerful hurricane vortex.
With increasing global warming, achieving the critical temperatures in the
oceans will be easier than ever before, spawning more hurricanes with more
energy to unleash upon our coastlines. The message is clear. The Caribbean
and US will be hit more often, by bigger, meaner hurricanes. The good news
is that by knowing this, it should be possible to improve the evacuation
procedures and save lives.
Dr Mark Maslin is a marine geologist at the Environmental Change Research
Centre, Department of Geography, University College, London.
© Copyright Guardian Media Group plc.1998
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