BBC News Online: Sci/Tech (annotations in [[brackets]])
 
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                Thursday, 25 November, 1999, 08:48 GMT 
                Ocean drift disruption may chill Europe
        Scientists have found evidence that the Atlantic Ocean current
         which gives Europe its mild climate is being disrupted. 
 
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        "This is the largest change we have seen in the last 100 years" -
                        Dr Bill Turrell 
 
If it stopped, then the temperatures in western Europe would plunge by
five degrees Celsius, creating bitter winters.  The culprit for the
changes could, ironically, be global warming. 
 
The current, called the North Atlantic Drift, brings warm water
northwards from the Gulf Stream.  It is being disrupted by a growing
amount of freshwater entering the Arctic Ocean, reports New Scientist
magazine. 
 
[[Freshwater, such as you'd get from the melting of the Arctic icepack.
The ice over the Arctic sea has become quite a bit thinner, and the
season it is totally frozen is already shortening to the point that
polar bears are in danger of losing their food supply.]]
 
This increase is a result of changes attributed to climate change and
possibly global warming:  melting ice, increased rainfall and changing
wind patterns. 
 
                Global conveyor belt
 
The North Atlantic Drift is part of a global conveyor belt that brings
warm, surface water north from the Gulf of Mexico and sends cold, deep
water back. 
 
[[Saline water is the other half of the conveyor; the water which falls
has to be relatively dense, and the additional salt is the key.  The
Gulf Stream currents from the Carribean apparently supply the salt.]]
 
The belt is driven by two "pumps", one in the Greenland Sea and one in
the Labrador Sea, where the surface water cools, becomes denser, sinks
and then returns south. 
 
A computer model developed by Stefan Rahmstorf of the Potsdam Institute
in Germany has already suggested that global warming could turn off the
North Atlantic Drift but there has been no evidence that this is really
happening.   [[Yet.]]
 
However, several teams are now reporting changes which fit in with the
model's predictions.  Bill Turrell, leader of the Ocean Climate Group
at the Scottish Executive's Marine Laboratory in Aberdeen, analysed
more than 17,000 measurements of seawater salinity between Shetland and
the Faroe Islands collected since 1893. 
 
[[This can be added to the thousands of temperature measurements in
zones which have not experienced changes in land usage patterns, but
have nevertheless seen increased averages.  The salinity data is
another set of facts for the warming denialists to deny.]]
 
Dr Turrell found that in each of the past two decades the salinity of
the deep water flowing south has dropped by 0.01g of salt per kg of
seawater.  So its density has probably also decreased. 
 
[["Probably", because you can't measure the in-situ temperature of a
slug of 1893 seawater in a bottle in a museum.  But very suggestive.]]
 
"This is the largest change we have seen in the outflow in the last
100 years," says Dr Turrell.  "It is consistent with models showing the
stopping of the pump and the conveyor belt." 
 
This contrasts with the situation in the 1950s when the salinity of
the outflow was so stable it was used to calibrate equipment. 
 
[[From calibration-quality to indicator of catastrophe.  Isn't that
enough of a wake-up call for you?]]
 
                Warm water 
 
His findings are echoed by work at the Fisheries Laboratory of the
Faroes.  Monitoring conducted there suggests the deep-water outflow
through the channel to the southwest of the islands is getting warmer. 
 
[[Both warmer and less saline.  Cold and salt are the engines which
drive the current.  What happens to the east coast of the USA if the
Gulf Stream goes away?]]
 
In a study yet to be published, Bogi Hansen of the lab says the level
at which water is at -0.5C sank by 60 metres between 1988 and 1997. 
 
Svein Osterhus of the University of Bergen in Norway has also
discovered that a deep-sea current closer to the Arctic has gone into
reverse.  In 1982 and 1983, deep water flowed southwards from the
Greenland Sea into the Norwegian Sea at 10 centimetres per second. But
in 1992 and 1993, the water was flowing at one centimetre per second 
in the opposite direction. 
 
This indicates that the Greenland Sea pump "has been dramatically
reduced in power", says Dr Xsterhus. 
 
[[Note, this is the third independent measurement indicating the
same thing.  One is a glitch.  Two is a split decision.  Three is
unanimous.  It is time to be afraid.]]
 
"Any evidence that changes in ocean currents are starting to occur is
very important," says computer modeller Dr Rahmstorf.  "The freshening
and warming of the deep water flowing back into the Atlantic is
consistent with global warming but could also have natural causes." 
 
[["Could"... but do you want to bet your climate on it?]]

109 responses total.

Fall Agora item #157 is linked as Science #57.

Another hit Don Quixote!  Frankly, computer models are simply prejudiced
by the assumptions that the programmer makes and the limited actual raw
data on the long term cycles of the earth, that I hardly think mandifest
themselves within the 170 year sample data.  We can only guess, maybe, global
temperature rise caused by human action might possibly in the slightest way 
be responsible for shifts in patterns hundreds of millions of years old.

I guess my point really is...

How can one conjecture the exact state and span of a deck of cards if you
only see 7 consectutive cards from the middle of the deck.

  Obviously one cannot predict exactly what will happen without both complete
  knowledge about the current state and understanding of how future states
  arise from the present state.

  However, the fact that our knowledge is incomplete doesn't mean that we are
  totally unable to make useful predictions.  If today is 80 degrees (F) it
  doesn't necessarily mean that it won't snow tomorrow, but one can conclude
  that with a fairly high degree of likelihood and a rational person would
  make their plans accordingly..

Re #2,3: the deck of cards analogy in inappropriate as an unknown or
shuffled deck has no correlation between cards at different locations
(other than those imposed by the deck being finite - if you know 51 of the
cards, you can predict the 52-nd with near 100% accuracy).

Climate prediction is not done by taking 170 years of data and trying to
extrapolate those. That would be like Ptolomeic astronomy, when the laws
of planetary motion were not known. 

Climate however, follows laws of thermodynamics, mass blances, momentum
balances, and heat transfer by convection and radiation. The laws for
these are known with considerable accuracy. Likewise astronomical laws are
also well (vastly better) known. The problems lie in the size and
complexity of the system and in having computational power to deal with
those. This is still far from sufficient. There are also inherent chaotic
properties, which call for greater and greater accuracy of information on
initial and boundary conditions as one attempts to extend a prediction
further into the future. There is no *inherent* reason why it cannot be
done, and therefore eventually climate prediction will be a pretty
accurate technology.

However, extrapolation of the results and declaring that one basic factor
might be responsible (which is what the article above does do), without
knowledge of what the planet "HAS DONE" with such conditions, appears to me
to be completely biased and presumptive.  Terms like "possibly" and "could"
taint the subject severely, and the poster's last line clearly exhibits
the bias.  The article itself pretends to offer a weak "natural cause"
theory, but the rest of the article is pretty blatant in making dire 
preditions from the inferrence of global warming.

Everyone knows that in these political times, global warming is a buzz word
meaning "human caused change", otherwise "naturally occuring" would
be guilty until proven innocent.

We can't prove for absolute certain that we're doing it, but can we take
that chance?  If we assume it's not us, and we're wrong, the results are
catastrophic.

I don't live life on the edge.  I don't live life afraid that my next move
will be my last.  If I did, I'd be frozen in place.  

Re #2:  You're arguing a falsehood (that there is no physical basis
for the climate models).  Let me substitute a few words and see if
you agree that the argument is faulty:
 
        "... Weather models are simply prejudiced by the assumptions
        that the forecaster makes and the limited actual raw data
        on the long-term cycles of the weather."
 
Nothing is ever 100% certain except in mathematics.  We're seeing trends
in warming, ocean circulation, ice cover and many other phenomena which
increasingly confirm the models which predict warming based on human
activities.  Panic is silly since the results will take 20-50 years to
develop, but failing to address the issue NOW is stupid; the time to
prepare is before the consequences are fully upon us, not after.
 
Re #7:  gull said it better than I could.  And the real irony is, we should
be doing a lot of things which reduce CO2 emissions just because they are
smart financial moves; even if the climate models are wrong, we'd still be
better off for grabbing the savings that result.  Some of this we should
have begun 27 years ago when the first oil-price shocks hit.

Re #8: And what's that supposed to mean?  That it's somehow cowardly to
think about what effect we might be having on the future?

Let me explain again.  We have some very convincing evidence that we're
causing something that will result in major problems for us. We can't be
absolutely sure that it's us, but it seems very likely. 

Now, don't you think maybe we should change what we're deing to try to
prevent this?  The risks are too great to ignore, and if we decide to 'wait
and see' it'll be too late.

Yuh know, this 'global warming' debate reminds me a lot of the 'debate'
over the y2k thingy - back in the 80s.

That must mean that you are really stocking up on ice cubes in preparation
for global warming. 

No, it was a much more subtle observation than you obviously could
comprehend.

Thinking about things like global warming is not good because otherwise
we might feel guilty about our egocentric, excessive behavior ;-)

I like #13 - someone squiggling out of a personal contradiction. 

Exactly -- if we'd started seriously doing something about Y2K problems back
in the 80's, we wouldn't be scrambling now.  Good analogy, bdh.

        As I recall, our beloved prez passed legislation passed a bill
        protecting all firms from suites from "the people", too..

        Personally, I found this to be the most damning indictment against
        the entire gig.. S'not like the millenium was a suprise, is it?

        Surely everyone has had since at least 1970 to see and say, "Gee..
        I wonder what happens when we hit jan/1/2000?"

(Fine.  So imagine 'em a while down the line saying "Surely everyone has had
since at least, oh, 1990 to think about this atmosphere thing")

Re #s 11 and 16: I have come to the conclusion that there is little in the
analogy of the Y2K 'problem' and global warming, except that both have
been mentioned early on. But someone mentions the problems-to-come (right
or wrong) early on for just about every technology that man has employed. 
Analogies have to be seen in a whole scenario. The Y2K thing is really a
small problem blown up by not just ignoring it for some time, but by
letting it happen in the first place. Even at this late date, and even
though it has given millions of dollars of employment to computer workers,
it was never a really threatening problem and I don't expect to see any
dramatic consequences (accidents and intentional mayhem are much bigger
threats at Y2K). Global warming, however, is tied intimately to the very
substance of the industrial revolution, our current economies, the
development of nations, and so forth. Whatever costs are to come as global
warming proceeds are likely to absolutely dwarf the costs of Y2K computer
problems. They will dwarf the total value of all computers, in fact. And
there is no quick fix, as the effects are cumulative with really unknown
consequences (it was known what computers might do at Y2K). Global warming
is also so controversial because of entrenched political, economic,
resource, and public interests: nothing of like magnitude has hampered
addressing the Y2K computer problems.

It is easy to name other problems facing humanity that also vastly dwarf
the Y2K 'bug': fisheries, fresh water, clean air and water (pollution and
waste disposal in general); living space and quality; new diseases and the
regrowth of old diseases....the list can go on. 

In two months Y2K will be just a blip. All those other problems will
still be with us.

"All those other problems will still be with us" is very true.  We differ
on the cause and effect.  I continue to contend that global changes, whether
they are temperature increases or decreases are within perfectly reasonable
tolerance levels for our globe.  Weather pattern changes are also quite
a fact of life on this planet.  

Industrial age thermadynamics are not going to make the earth
uninhabitable.  Just as the earth itself will go through pattern changes,
so too will it be changed by man.  At some point, man may be able to
control the weather.  Would this be a "BAD THING (tm)".  Certainly it
would not be what the earth itself would provide.

In any case, I see this discussion as "oh my god, we're changing our
environment and it will kill us!"  Trying to bring a little sanity to
this discussion, my contention is that any changes will be tolerable
exchange for our continued development of and on this planet.  Perserving
our atmospheric condition is a lost cause.  Not because we are playing
with fire, but because it's going to change of it's own accord anyway.
Until we get some real environmental controls, we're just wringing our
hands and fretting about the future in a waste of personal energy.

Doing something about it is vastly preferable to wringing hands and fretting.
Much can be done about it, even without much real inconvenience to
ourselves, such as reducing waste of all kinds, controlling population,
etc.

  re #20:  perhaps the more hysterical elements are screaming "we're
  changing our atmosphere and it will kill us!" but it would be better
  to listen to the experts in the field who are almost all telling us
  "we're changing our atmosphere and it's going to have unpredictable
  consequences, most of which are likely to be unpleasant."

  Perhaps the death-and-doom-sayers get more attention because they're
  louder and their message is more dire but the message of the experts
  is clear enough -- that conditions *are* changing and that results
  will follow which *will* be "BAD THINGs (tm)"

  Yes, we'll still be able to live on the planet if even the most dire
  predictions of responsible scientists turn out to be the case, but
  the planet may not be able to support nearly so many of us..

And we may have to move....

Has anyone speculated on what effect global warming might have on the Great
Lakes?  As some of you may be aware, Lake Michigan and Lake Huron are
currently about two *feet* below normal levels, and Superior is down six
inches.  I think this is in the range of normal variation, but I'm curious
what the future may hold.

Gosh, I really never knew that "different" = "unpleasant".  I appreciate
the education.

Basically to rephrase Mike's statement:
           
   "we're changing our atmosphere and it's going to have unpredictable
   consequences, most of which are likely to be unpleasant."

   "we may be changing our atmosphere, and we don't know what the
    results will be, but let's assume worst case and then presume it
    as fact."

Different?  Sure, I'll accept that.  Unpleasant?  I'm sure that some
people will be put out, perhaps even die.  Bad?  I'm not even close to
accepting that.

Our world is made up of many different climates.  Here in Michigan,
there are days both hot and cold that I consider INTOLERABLE.  Take
the worst hot day, and talk to a Texan or a Floridian and the'll laugh
in your face.  Take the worst cold day and talk to a Albertan, you'll
get the same reaction.

Humans are capable of surviving and thriving under some pretty
difficult conditions and consider it the status quo... and we haven't
even considered Siberia or Egypt.  Man has migrated long distances
during his tenure on this planet.  Man has also died from being too
stubborn to accept that environmental change has made a place less
survivable.  It will happen again, and is happening now *without*
man doing anything to cause the problem.

Things change.  Man adapts.  Man cannot change the fact that our
environment *WILL* continue to change.  We might as well get some
benefit from it.

  What benefit do we get from coastal flooding, the spread of deserts, etc?

        More profit on Real-Estate as the "seafront" properties change and
        the "access to Pleasant Dunes" increases.

Things change.  Man adapts.  Most other species adapt much less well.  The
most real danger from global warming seems to be to our crops, our livestock,
our forests, and so on, and not to us directly; but what harms our crops &c
harms us indirectly.

        How long is the timeline of our recorded weather conditions?
        (and I do NOT mean 'geological recrods', although they are grist
        for the mill)

        Then analyse the geological evidence for centuries & eons between
        changes.

        Now, start pointing at the "little things" we can do, over
        time (rather than all in a lump).

        meanwhile, as I've mentioned before, yer trapped in yer
        petri-dish: better start planning and engineering to climb those
        walls and get out on the lab-bench.

I'm amazed that you all consider coastal flooding and desert growth
preventable and/or inevitable.  It is certainly one of the more 
dramatic scenarios presented as "dangerous."  Indeed, if it does happen,
it will affect a lot of rich and stupid people.

Climate changes will require agricultural adaptation, habitat change,
lifestyle change, and bring a new social order.  It is a freight train,
and our input to it is just a headwind or tailwind.  It merely changes
the arrival time.  NONE of you can know whether we are preventing more
dramatic catastrophe or enhancing it.  You only want to observe the
short term changes and project them into catastrophic disaster.
Preserve what we know, even if keeping things the same has unknown
dangerous consequences itself.

Yeah, some critters won't adapt to environmental change.  The
dinosaurs didn't.  Billions of species have already come and gone on
this planet, of which our current ecosphere snapshot is only a tiny,
tiny click.  Perhaps the pandas were never meant to survive beyond a
defined point in time, while cockroaches are going to out-survive even
us.  I can't and won't be afraid of the evolution of the planet from
minor input into the system.  Short of total and complete ecosphere
reboot, we will adapt and survive, and lose some things, and gain some
things.

sno has now stepped back..about as far as Betelgeuse..and is passing
judgements on that far-off little speck of light that perhaps has
a planet circling it.

For what its worth, which appears very little to sno, this planet is
our home. That means a lot to people. They should no more take an
off-handed, indeed supercilious, attitude toward the planet earth
and its future than they take toward their own homes. 

sno has been reading Fitzgerald, it would appear.

My theory is that an advanced form of Dinosaur evolved a sentient 
society over the space of about 100,000 years, spent 3,000 years 
building cities and edifices, and either left the planet or destroyed 
all the dinosaurs with its own environmental chaos.  It could happen.

So, sno, why are you so sure this is a natural change, and not one brought
on by humans?  I believe it's been shown scientifically that we're producing
easily enough CO2 to cause the observed changes...  To me, your argument
sounds a little like someone who's just dumped cyanide in a stream saying,
"Oh, but those fish would have died eventually anyway."

        Define "unnatural change" ;-)

One produced by the application of (so called) intelligence. We probably
should use a different term for it, such as nonpurposive vs purposive
changes.  But the word "natural" has become associated with nonpurposive
changes, so that unnatural by extension means purposive. The two types of
changes are quite different in origin so should be distinguished in the
language. 

I never said thermal changes were automatically natural or
alternatively unnatural.  I'm stating that it all is within the scope
of natural range of environmental behavior on this planet, regardless
of our input into the thermodynamics of our home.

I don't taken kindly to being called off-handed or haugty.  I think
I've been both polite and clear about my perspectives on this issue
without talking down or being insulting to other participants here.

There are very important things on this world that I consider very
serious business.  One that I have less enthusiasm for is fear of
environmental change, as if what will result will be less that what we
have now or have had in the short term past.  As I have stated before,
poisoning ourselves with short sighted garbage disposal, nuclear
radiation, or poor chemistry containment are much more serious
concerns.

Actually, it is interesting that Rane suggests that I'm observing from
the outside.  Betegeuse is his suggested reference point.  To be
perfectly honest, I accept that definition as a compliment.  I choose
not to personalize the environment as something that would be a
personal loss to me or humankind, because I fully expect that earth
will continue to experience climate changes all on its own, regardless
of our intervention.  Continents continue to shift, meteors continue
to strike, and the glaciers continue to melt (for now).  From the
outside observer perspective, I believe that a wider picture can be
seen, and perhaps a more realistic view of what humans should expect
can be apparent.

The loss of snail-darters and Pandas are interesting historically, but
I don't get emotional about it.  At some point, people will have to
change where they live and produce food.  Land ownership really has no
bearing here while coasts change, mud slides into the ocean, and
rivers change their winding path.  Agriculture has always been a
transient, opportunistic endeavor.  So, I'm not quite sure what all
this preservation talk is all about.  It's not going to stay the same.
The human species is not going to do much more than watch the show and
wish they had some control over it.

I agree with you that, sans humans, earth's enviroment would evolve,
and in time include large fluctuations. Ice ages will return and all
northern cities will be ground to powder. The oceans will rise or
fall by literally hundreds of meters. These changes mostly occur,
however, in geological time. It is short-cycle changes that are
precipitated by human actions that are of concern, both because they
can be in excess in the short term of what might happen without
such human causes, and because they are something we can do something
about. We build houses, a short term action, to change our immediate
environment. We can equally well take actions to not so deliberately
and greatly change the 'natural' environment in which our civilization
has evolved. 

I don't think we will ever agree on the concept of acceptable change when
you use the terms "deliberately" and "greatly change."  In no way can I
accept that anyone can presume to know how man can bring on catastrophic
environmental alteration without deliberate and malicious destruction
in an acute fashion.  Chronic modification of our world's dynamics is
part of the formula that the earth absorbs since fire was created by
man.  I'm not prepared to wipe man off the earth so that the conditions
that man currently enjoys will take a less disturbed path.

<RANT OFF>

Anyway, it all appears to be a measure of tolerance.  I'm willing to accept
and tolerate a path that includes man reaching the limits his environment
and tools permit of him.  This may mean that we sacrifice some beloved
aspects of today so that we might experience tomorrow more fully.  We
will likely always disagree on the magnitude and desirability of that
change.  I see it as a small sacrifice from a miniscule change.

Noone's suggesting we 'wipe man off the earth.'

If you don't like the arguments stated so far, how about one that appeals to
your business sense?  The cost of reducing CO2 emissions now is likely to be
cheaper than the cost of relocating costal populations, irrigating new
deserts so we can still produce food, and (for example) additional heating
costs in the parts of England that will suddenly have the climate of Norway.
Of course, our whole economic system is based on short-term profit, so this
doesn't show up well on the balance sheet, but it's still an important thing
to consider.  Or does the fact that most of these costs may not appear in
your lifetime mean that you refuse to concern yourself with them?

- Backtalk version 1.3.30 - Copyright 1996-2006, Jan Wolter and Steve Weiss