Natalie,
A lot of new thinking and research is going on now concerning climate
change and I think caution is needed before we need to worry too much.
For one thing the Gulf Stream does not so much speed up or slow down but
rather that its turning edge moves northwards or southwards. (The turning
edge is where the normal-density sea-water of the Gulf Stream meets
lighter-density sea-water coming from the melting of glaciers and sea-ice
in the Arctic -- and then sinks and retreats backwards towards the equator
like a conveyor belt.) But, essentially, winds drive sea currents, not the
other way round. The weather itself is more dependent on the way low
wind-streams and (thus rain-bearing low-clouds) are lifted by land masses
and "steered" by mountain chains. Thus, because there's much more land (and
many more mountains) in the Northern Hemisphere then we get more variable
temperatures and weather patterns up here than the Southern hemisphere.
There is also the anomaly that while air temperatures (mainly in the
Northern hemisphere) have still been rising, most oceans have been cooling
in the last two years -- 2004 and 2005. (The research mentioning warming of
the Atlantic in the article below was done in 1998 and is, any case, rather
trivial in comparison with the more recently recorded ocean cooling.) If
this ocean cooling persists then it will translate into cooler air
temperatures in due course and the present phase of global (mainly Northern
hemisphere) warming will come to an end. There are those, of whom I am one,
who believe that the global warming of recent decades has been mainly a
recovery of normal temperatures after the savage "mini ice age" of between
about 1400 and 1750 (which caused the River Thames in this country to
freeze several feet thick every winter). Even if the global warming
continues it is quite likely that it is another repeat of the "Medieval
warm period" of about 900 - 1300 (which the UN climate review people chose
to ignore in their "hockey stick" graphs).
The metaphor of the "greenhouse effect " is used so often that most people
don't realise that there's also a "coldhouse" sitting on top of it -- where
the high clouds are. This is shedding heat into outer space. Unfortunately
less is known about the radiative effects of this than the
radiation-absorption effects of CO2 (and H2O) in the "greenhouse" portion.
Very sophisticated experiments to determine the former will be started soon
by some of the most gifted scientists in the world at the CERN bubble
chambers. When the results of these are known in late 2007 or perhaps 2008
we wil have a much more accurate picture of the overall state of affairs
than the inferential reading of tree rings in bristle-cone pine trees of
the past few hundred or years or so (which is what the UN team mainly
relies upon for what temperatures might have been in the past)
Keith Hudson
At 11:16 02/12/2006 -0800, you wrote:
Perhaps some of you remember my film recommendation, "The Day After
Tomorrow", in which the Atlantic Ocean warms dramatically, and before long
we get to see New York City in a deep freeze. Very cool computer work. It
was produced in 2004, and may have been inspired by an actual 2002
Antarctic shelf collapse across a 1200 mile stretch.
Yesterday's Progressive Review featured an article from the Guardian which
discusses findings over the previous 7 years of observation of the Gulf
Stream. The upper 1500 metres has warmed by 0.015C, which UK scientist
James Lovelock, author of Gaia books I and now II, claims can cause a
surface temp. rise of up to 9C.
The Gulf Stream, which raises temperatures in Europe by 10C, and goes up
past Greenland to Scandinavia, has slowed by 30% in the last twelve years,
according to the article, and current itself has slowed by 6m tonnes of
water per second over the same period.
To me, that sounds more than alarming. Even with a slowing of 1-2%, it
sounds bad enough. It's not clear whether Lovelock was at all associated
with the team that conducted the 12 year research which may possibly help
prove some of his own global warming theories. Has anyone come across
anything which may confirm or cast any doubt upon this 12 year Gulf Stream
observation?
In a recent e-mail I also mentioned that there had been an actual
stagnation of this current, southwest of the UK I believe, for over 10
days, and that if it were to continue for 30 days or more, it could be
enough to initiate significant freezing.
Link to the Guardian article below.
Natalia
***************************************
DAVID ADAM, GUARDIAN - Global warming is creating a climate time bomb
by storing enormous amounts of heat in the waters of the north
Atlantic, UK scientists have discovered. Marine researchers at
Southampton and Plymouth universities have found that the upper 1,500
meters of the ocean from western Europe to the eastern US have warmed
by 0.015C in seven years. The capacity of the oceans to store heat
means that a water temperature rise of that size is enough to warm the
atmosphere above by almost 9C. . .
The findings were announced in the journal Geophysical Research
Letters as James Lovelock, the UK scientist who developed the gaia
theory of life on Earth, warned that such ocean warming could stifle
marine life and accelerate climate change. Professor Lovelock said
that thermal mixing of water and nutrients shuts down when the upper
layer of ocean water reaches about 12C. "That's why the tropical
waters are clear blue and the water in the Arctic looks like soup," he
said. Such a change would affect marine life, which research suggests
could help form clouds over the oceans. Warmer waters would receive
less protection from sunlight, which would warm them further. . .
Speaking before a lecture to the Institution of Chemical Engineers,
Prof Lovelock repeated the prediction, made in his recent book The
Revenge of Gaia, that global warming will kill billions of people this
century. He said the Earth was undergoing a rapid transition that
could boost temperatures by 8C, making large parts of the surface
uninhabitable and food production impossible. A hotter planet might be
able to support less than a tenth of its 6bn population. "We are not
all doomed," he said. "An awful lot of people will die, but I don't
see the species dying out."
<http://environment.guardian.co.uk/climatechange/story/0,,1959556,00.html>http://environment.guardian.co.uk/climatechange/story/0,,1959556,00.html
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