THE NEW ICE AGE
Alarm over dramatic weakening of Gulf
Stream
http://www.guardian.co.uk/science/story/0,3605,1654803,00.html?gusrc=rss
. Slowing of current by a third in 12 years could bring more extreme
weather
. Temperatures in Britain likely to drop by one degree in next decade
Ian Sample, science correspondent
Thursday December 1, 2005
The Guardian
Yet another scare!
This is what the real scientists say
1) NO COLLAPSE, NO COOLING - NOT EVEN
IF YOU QUADRUPLE CO2 CONCENTRATIONS
Geophysical Research Letters 32, no.12 (28 JUN 2005) p. 1-5
http://www-pcmdi.llnl.gov/projects/cmip/thcmip2.pdf
A model intercomparison of
changes in the Atlantic thermohaline circulation in response to
increasing atmospheric CO2 concentration.
J. M. Gregory 1,2, K.W. Dixon 3, R. J. Stouffer 3, A. J.Weaver 4, E.
Driesschaert 5,
M. Eby 4, T. Fichefet 5, H. Hasumi 6, A. Hu 7, J. H. Jungclaus 8, I.V.
Kamenkovich 9,
A. Levermann 10, M. Montoya 11, S. Murakami 12, S. Nawrath 10, A. Oka
6, A. P. Sokolov 13,
R. B. Thorpe 2
Abstract: As part of the Coupled Model Intercomparison Project,
integrations with a common design have been undertaken with eleven
different climate models to compare the response of the Atlantic
thermohaline circulation (THC) to time-dependent climate change caused
by increasing atmospheric CO2 concentration. Over 140 years, during
which the CO2 concentration quadruples, the circulation strength
declines gradually in all models, by between 10 and 50%. No model shows
a rapid or complete collapse, despite the fairly rapid increase and
high final concentration of CO2. The models having the strongest
overturning in the control climate tend to show the largest THC
reductions. In all models, the THC weakening is caused more by changes
in surface heat flux than by changes in surface water flux. No model
shows a cooling anywhere, because the greenhouse warming is dominant.
FULL PAPER at http://www-pcmdi.llnl.gov/projects/cmip/thcmip2.pdf
J.M. Gregory, Centre for Global
Atmospheric Modelling, Department of Meteorology, University
of Reading, PO Box 243, Reading RG6 6BB United Kingdom j.m.gregory@reading.ac.uk
(2) ICE GROWTH IN THE GREENHOUSE: A
SEDUCTIVE PARADOX BUT UNREALISTIC SCENARIO
Geoscience Canada, June, 2004
http://www.looksmartscience.com/p/articles/mi_m0QQS/is_2_31/ai_n6153471
by Andrew J. Weaver and Claude
Hillaire-Marcel
ABSTRACT
The recent IPCC (2001) assessment stated that
"Most models show weakening of the Northern Hemisphere Thermohaline
Circulation (THC),
which contributes to a reduction of surface warming in the northern
North Atlantic.
Even in models where the THC weakens, there is still a warming over
Europe due to
increased greenhouse gases."
However, there is still a widespread misunderstanding of the possible
consequence of climate change on the Atlantic Ocean Meridional
Overturning. In particular, it is often touted, especially in the
media, that a possible consequence of anthropogenic greenhouse gas
emissions is: "the onset of the next ice age". Here we document the
history of this misconception and quantitatively show how it is
impossible for an ice age to ensue as a consequence of global warming.
Through analysis of the paleoclimate record as well as a number of
climate model simulations, we also suggest that it is very unlikely
that the Atlantic Meridional Overturning will cease to be active in the
near future. We further suggest that a region where intermediate water
formation may shut down is in the Labrador Sea, although this has more
minor consequences for climate than if deep water formation in the
Nordic Seas were to cease.
[...]
CONCLUSIONS
While much has been made in the media of global warming potentially
leading to the onset of the next ice age, we believe we have shown that
this is simply not possible. A more relevant question is what will
happen to the AMO during the course of the next century. Some models
assessed in IPCC (2001) find no reduction of the AMO during the 21st
century while others find a slight reduction in its strength. Such a
reduction leads to a negative feedback to anthropogenic warming in and
around the North Atlantic. That is, through reducing the transport of
heat from low to high latitudes, SSTs are cooler than they would
otherwise be if the AMO was left unchanged. As such, warming is reduced
over and downstream of the North Atlantic. It is important to note that
in all models where the AMO weakens, warming still occurs downstream
over Europe. While admittedly model-dependent, even in the case where
we added an additional external freshwater perturbation to the North
Atlantic for 500 years, whose magnitude was chosen to account for the
upper estimate of the observed rate of global sea level rise this past
century, we still do not get a cessation of the AMO and cooling down
stream over Europe.
Worth mentioning here is the fact that the most sophisticated non
flux-adjusted model of Wood et al. (1999) suggests that the freshening
of North Atlantic surface waters presently observed (Curry et al.,
2003) could be associated with an increasing AMO (Wu et al., 2004).
This same model, praised by Rahmstorf (1999) as giving "for the first
time a realistic simulation of the large scale ocean currents", also
suggests that eventually it is only Labrador Sea Water formation that
is susceptible to a collapse as it did during the most recent warmer
episodes of the Earth Climate history (Hillaire-Marcel et al., 2001).
Climate change is offering decision makers and society as a whole many
important challenges that need to be assessed and addressed, including
the possibility of a reduction in the strength of the AMO or the very
remote possibility of its cessation this century. One thing that they
need not concern themselves with is Global Warming causing the onset of
the next ice age. Unfortunately, such a conclusion is far less
newsworthy than the one warning of the occurrence of an impending ice
agc.
(3) GULF STREAM SAFE IF WIND BLOWS AND EARTHS TURNS
Nature 428, 601, April 8, 2004
http://www.nature.com/news/2004/040405/full/428601c.html
Sir - Your News story "Gulf Stream probed for early warnings of system
failure"
(Nature 427, 769 (2004)) discusses what the climate in the south of
England would
be like "without the Gulf Stream." Sadly, this phrase has been seen far
too often,
usually in newspapers concerned with the unlikely possibility of a new
iceage in
Britain triggered by the loss of the Gulf Stream.
European readers should be reassured that the Gulf Stream's existence
is a consequence
of the large-scale wind system over the North Atlantic Ocean, and of
the nature of
fluid motion on a rotating planet. The only way to produce an ocean
circulation
without a Gulf Stream is either to turn off the wind system, or tostop
the Earth's
rotation, or both.
Real questions exist about conceivable changes in the ocean circulation
and its climate
consequences. However, such discussions are not helped by hyperbole and
alarmism. The
occurrence of a climate state without the Gulf Stream anytime soon -
within tens of
millions of years - has a probability of little more than zero.
Carl Wunsch
Earth, Atmospheric and Planetary Sciences,
Massachusetts Institute of Technology
That is probably enough to be going on with,
Vincent Gray
75 Silverstream Road
Crofton Downs
Wellington 6004
New Zealand
Phone/Fax 064 4 9735939
"It's not the things you don't know that fool you.
It's the things you do know that aint so"
Josh Billings