Physics Today: Rapid climate change
James Acker
Union (AGU) gets you a subscription to Physics Today, and at least
80% of the content is beyond my comprehension (usually out of my
field). But the August issue has an article called "The Discovery
of Rapid Climate Change" that's quite interesting.
Online here (longer and with fully-linked references):
http://www.aip.org/history/climate/rapid.htm
Apparently the author of the piece, Spencer Weart, has
a book out entitled "The Discovery of Global Warming" (Harvard
University Press).
Jim Acker
*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
Jim Acker
jac...@gl.umbc.edu
"Since we are assured that an all-wise Creator has observed the
most exact proportions, of number, weight, and measure, in the
make of all things, the most likely way therefore, to get any
insight into the nature of those parts of the creation, which
come within our observation, must in all reason be to number,
weigh, and measure." - Stephen Hales
Thomas Palm
@news.umbc.edu:
> Just wanted to note: being a member of the American Geophysical
> Union (AGU) gets you a subscription to Physics Today, and at least
> 80% of the content is beyond my comprehension (usually out of my
> field). But the August issue has an article called "The Discovery
> of Rapid Climate Change" that's quite interesting.
>
> Online here (longer and with fully-linked references):
> http://www.aip.org/history/climate/rapid.htm
>
>
> Apparently the author of the piece, Spencer Weart, has
> a book out entitled "The Discovery of Global Warming" (Harvard
> University Press).
You can find it all at the same site:
http://www.aip.org/history/climate/
It's a very useful reference.
Eric Swanson
The history of the AGW debate up to the year 1980 is even more interesting:
http://www.aip.org/history/climate/Public.htm#M_63_
and continuing after 1980:
http://www.aip.org/history/climate/public2.htm
William Connolley should be envious, as there are many references to the
so-called "Global Cooling Scare" and a discussion about it's development.
--
Eric Swanson --- E-mail address: e_sw...@skybest.com :-)
--------------------------------------------------------------
w...@bas.ac.uk
>The history of the AGW debate up to the year 1980 is even more interesting:
> http://www.aip.org/history/climate/Public.htm#M_63_
>and continuing after 1980:
> http://www.aip.org/history/climate/public2.htm
>William Connolley should be envious, as there are many references to the
>so-called "Global Cooling Scare" and a discussion about it's development.
I browsed those pages. I agree they are a useful resource but they are
also somewhat disappointing in that there is very little material
direct from the references persented (unlike my pages, hurrah!).
-W.
--
William M Connolley | w...@bas.ac.uk | http://www.antarctica.ac.uk/met/wmc/
Climate Modeller, British Antarctic Survey | Disclaimer: I speak for myself
I'm a .signature virus! copy me into your .signature file & help me spread!
Thomas Palm
> Eric Swanson <swanson> wrote:
>>The history of the AGW debate up to the year 1980 is even more
>>interesting:
>
>> http://www.aip.org/history/climate/Public.htm#M_63_
>>and continuing after 1980:
>> http://www.aip.org/history/climate/public2.htm
>
>>William Connolley should be envious, as there are many references to
>>the so-called "Global Cooling Scare" and a discussion about it's
>>development.
>
> I browsed those pages. I agree they are a useful resource but they are
> also somewhat disappointing in that there is very little material
> direct from the references persented (unlike my pages, hurrah!).
Have you sent the author a link to your page? Since it is a hypertext
document it can be easily updated.
Alastair McDonald
"Thomas Palm" <Thoma...@chello.removethis.se> wrote in message
news:Xns93D177CDCEA69T...@212.83.64.229...
I don't think that would be very useful. Spencer Weart has written a
history. Why should he be interested in William Connelly's attempt
to rewrite history?
Cheers, Alastair.
Ian St. John
"Alastair McDonald" <alas...@abmcdonald.leavethisout.freeserve.co.uk> wrote
in message news:bgvt4g$uf9$1...@newsg3.svr.pol.co.uk...
You claim that William has written something false? Please back up your
claim.
Show ONE thing on Williams page that is a falsehod, or one fact from Spencer
that should be included.
The only issue here is whether any 'authority' in the '70s make
pronouncements of the dangers of global cooling and predicted a disaster.
The ravings of lunatics are not at issue. Nor is popular science. If Popular
science makes an article on the trip to mars or the dynamics of flying
saucers it does not mean that we have visited mars or that UFOs are real.
Everyone is aware of that.
Your move.
Thomas Palm
wrote in news:bgvt4g$uf9$1...@newsg3.svr.pol.co.uk:
> "Thomas Palm" <Thoma...@chello.removethis.se> wrote in message
> news:Xns93D177CDCEA69T...@212.83.64.229...
>> w...@bas.ac.uk wrote in news:3f33...@news.nwl.ac.uk:
>> > also somewhat disappointing in that there is very little material
>> > direct from the references persented (unlike my pages, hurrah!).
>>
>> Have you sent the author a link to your page? Since it is a hypertext
>> document it can be easily updated.
>
> I don't think that would be very useful. Spencer Weart has written a
> history. Why should he be interested in William Connelly's attempt
> to rewrite history?
They cover different subjects. Weart tries to describe history as it was,
William is trying to debunk a specific myth about how it was supposed to
have been. He is debunking the people trying to rewrite history.
Alastair McDonald
Unfortuately he is not debunking a myth. There was a scare in the 70s
about another ice age, even if it was so long ago it is only a myth to
those of William's age. Weart identifies C.E.P.Brooks as warning of
an abrupt climate change, long before the evidence from fossil beetles
and ice cores was available. Moreover, Fred Hoyle also warned of this
danger, and William now has a reference G.J. Kukla & R.K. Matthews,
Science, 178, 190-1, 1972: but appears not to have read it. The full text
can be read at;
http://links.jstor.org/sici?sici=0036-8075%2819721013%293%3A178%3A4057%3C190%3AWWTPIE%3E2.0.CO%3B2-Q
Here is an excerpt from that meeting report;
" At the end of the working conference, the majority of the particpants agreed
the following points:
The global environments of the last several millennia is in sharp contrast
with climates that existed during most of the past million years. Warm
intervals like the present one have been short lived and the natural end of
our warm epoch is undoubtably near when considered on a geological
time scale. Global cooling and related rapid changes of environment,
substantially exceeding the fluctuations experienced by man in historical
times, must be expected within the next few millennia or even centuries.
In man's quest to utilise global resources, and to produce an adequate
supply of food, global climate change constitutes a first order
environmental hazard which must be thoroughly understood well in
advance of the first global indications of deteriorating climate.
Interdisciplinary attacks on these problems must be internationally
organised and encouraged to develop at a rate substantially exceeding
the present rate."
Among those present at the meeting were R.G.Barry, C. Emiliana,
J. Imbrie, W. Ruddiman, C.B.Schultz, N.J.Shackleton, and P.W. Weyl.
Contributions were recieved from among others Broecker, Dansgaard,
and Schneider.
The problem of abrupt climate change has not gone away. The next event
has got closer. Moreover we now know that the speed of these event is not
millenia or centuries but in fact decades and years. Denying that scientists
predicted an imminent ice age is pointless. That is the spin the public
received. We should now concentrate in getting it across that the threat
of a rapid climate change has not gone away, only it will be to a warmer
state. If we come out with something so obviously true then perhaps we
can persuade them there is a danger.
Cheers, Alastair.
H. E. Taylor
<alas...@abmcdonald.leavethisout.freeserve.co.uk> Alastair McDonald wrote:
> "Thomas Palm" <Thoma...@chello.removethis.se> wrote in message
> news:Xns93D177CDCEA69T...@212.83.64.229..
>>> Eric Swanson <swanson> wrote:
>>>>The history of the AGW debate up to the year 1980 is even more
>>>>interesting:
>>>>
>>>> http://www.aip.org/history/climate/Public.htm#M_63_
>>>>and continuing after 1980:
>>>> http://www.aip.org/history/climate/public2.htm
>>>
>>>>William Connolley should be envious, as there are many references to
>>>>the so-called "Global Cooling Scare" and a discussion about it's
>>>>development.
>>>
>>> I browsed those pages. I agree they are a useful resource but they are
>>> also somewhat disappointing in that there is very little material
>>> direct from the references persented (unlike my pages, hurrah!).
>>
>> Have you sent the author a link to your page? Since it is a hypertext
>> document it can be easily updated.
>
> I don't think that would be very useful. Spencer Weart has written a
> history. Why should he be interested in William Connelly's attempt
> to rewrite history?
>
Alastair, I think you need to substantiate this claim.
<grumpy olde skeptic>
-het
--
"You know, I don't understand why humans evolved as such thoughtless, shortsighted creatures."
"Well, it can't stay that way forever."
"You think we'll get smarter?"
"That's one of the two possibilities."
-Calvin and Hobbes
Global Warming: http://www.autobahn.mb.ca/~het/globalwarming.html
H.E. Taylor http://www.autobahn.mb.ca/~het/
Eric Swanson
alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>
>
>"Thomas Palm" <Thoma...@chello.removethis.se> wrote in message
>news:Xns93D189116E131T...@212.83.64.229...
>> "Alastair McDonald" <alas...@abmcdonald.leavethisout.freeserve.co.uk>
>> wrote in news:bgvt4g$uf9$1...@newsg3.svr.pol.co.uk:
>>
>> > "Thomas Palm" <Thoma...@chello.removethis.se> wrote in message
>> > news:Xns93D177CDCEA69T...@212.83.64.229...
>> >> w...@bas.ac.uk wrote in news:3f33...@news.nwl.ac.uk:
>> >
>> > history. Why should he be interested in William Connelly's attempt
>> > to rewrite history?
>>
>> They cover different subjects. Weart tries to describe history as it was,
>> William is trying to debunk a specific myth about how it was supposed to
>> have been. He is debunking the people trying to rewrite history.
>
>Unfortuately he is not debunking a myth. There was a scare in the 70s
>about another ice age, even if it was so long ago it is only a myth to
>those of William's age. Weart identifies C.E.P.Brooks as warning of
>an abrupt climate change, long before the evidence from fossil beetles
>and ice cores was available. Moreover, Fred Hoyle also warned of this
>danger, and William now has a reference G.J. Kukla & R.K. Matthews,
>Science, 178, 190-1, 1972: but appears not to have read it. The full text
>can be read at;
>http://links.jstor.org/sici?sici=0036-8075%2819721013%293%3A178%3A4057%3C190%3
AWWTPIE%3E2.0.CO%3B2-Q
FYI, the URL does not work when one does not have the appropriate connection.
It also does not work even if one is in the U.S. with a subscription.
What are you, some university undergrad student???
>Here is an excerpt from that meeting report;
>" At the end of the working conference, the majority of the particpants agreed
>the following points:
>
>The global environments of the last several millennia is in sharp contrast
>with climates that existed during most of the past million years. Warm
>intervals like the present one have been short lived and the natural end of
>our warm epoch is undoubtably near when considered on a geological
>time scale. Global cooling and related rapid changes of environment,
>substantially exceeding the fluctuations experienced by man in historical
>times, must be expected within the next few millennia or even centuries.
>In man's quest to utilise global resources, and to produce an adequate
>supply of food, global climate change constitutes a first order
>environmental hazard which must be thoroughly understood well in
>advance of the first global indications of deteriorating climate.
>Interdisciplinary attacks on these problems must be internationally
>organised and encouraged to develop at a rate substantially exceeding
>the present rate."
>
>Among those present at the meeting were R.G.Barry, C. Emiliana,
>J. Imbrie, W. Ruddiman, C.B.Schultz, N.J.Shackleton, and P.W. Weyl.
>Contributions were recieved from among others Broecker, Dansgaard,
>and Schneider.
>
>The problem of abrupt climate change has not gone away. The next event
>has got closer. Moreover we now know that the speed of these event is not
>millenia or centuries but in fact decades and years.
Given the level of understanding of the day, the notion that an Ice Age begin
within a few millenia was not far fetched. However, the scientists of the day
didn't say for certain that one was GOING to occur in the immediate future.
Similarly, the notion that only a few years remain before major changes in
climate kick in is equally out of touch with the science of today. There is
not enough known about possible abrupt changes to say for certain WHEN the
next big jump will occur.
>.....Denying that scientists
>predicted an imminent ice age is pointless. That is the spin the public
>received. We should now concentrate in getting it across that the threat
>of a rapid climate change has not gone away, only it will be to a warmer
>state. If we come out with something so obviously true then perhaps we
>can persuade them there is a danger.
From the U.K., you probably don't get blasted by the denialists who have been
promoting the notion that the so-called Global Cooling Scare represented a
failed prediction, which is then taken as an excuse to ignore the current
scienctific understanding about Global Warming. In a sense, the denialists are
heaping manure on the previous concerns about an impending Ice Age to
indirectly bury the newer research that points out that indeed, a return to Ice
Age conditions in some locations may result from Global Warming. See my
comment on your posting of the paper by SEAGER et al.
Alastair McDonald
"Eric Swanson" <swanson@nospam_on.net> wrote in message
news:bh166c$3bsl$1...@news3.infoave.net...
I can't get it to work either. What you need to do is log into your AAAS
account, then go to JStor and browse issue 178. A search will not find it
because it is not a paper, only a meeting report.
Well, I think it is obvious but no one will take me seriously. When the
Arctic
ice melts there will be a large change in planetary albedo which will trigger
a rapid change. It is the sudden formation and collapse of sea ice sheets
which causes rapid climate change.
> >.....Denying that scientists
> >predicted an imminent ice age is pointless. That is the spin the public
> >received. We should now concentrate in getting it across that the threat
> >of a rapid climate change has not gone away, only it will be to a warmer
> >state. If we come out with something so obviously true then perhaps we
> >can persuade them there is a danger.
>
> From the U.K., you probably don't get blasted by the denialists who have
been
> promoting the notion that the so-called Global Cooling Scare represented a
> failed prediction, which is then taken as an excuse to ignore the current
> scienctific understanding about Global Warming. In a sense, the denialists
are
> heaping manure on the previous concerns about an impending Ice Age to
> indirectly bury the newer research that points out that indeed, a return to
Ice
> Age conditions in some locations may result from Global Warming. See my
> comment on your posting of the paper by SEAGER et al.
I have two problems with that. First the scare did happen, and it was
initiated
by scientists. The public are not fools so if we deny that, we are only seen
as liars, which makes our case worse.
Second, the idea that global warming can lead to cooling is absurd, even
if it were true. It could only work if on average there was not much warming.
Therefore the public say to themselves "The warming cannot be that great,
why worry." Or they say "These scientists have got their heads in the clouds.
They are always coming up with scary stories etc. ..." This also weakens
our case.
I have always been skeptical about a repeat of the Younger Dryas happening
as a result of global warming. But now I know that it is the sea ice sheets
which trigger these events, then it is impossible. Wally Broecker has also
changed his mind about the NADW being the trigger and now thinks it
is sea ice. I can dig out a reference if you like.
The problem has been it is oceanographers who have been leading the
charge in investigating abrupt change. Meteorology is where it happens.
And other sciences such as paleobiology and geomorphology have
also got a part to play.
HTH,
Cheers, Alastair.
Eric Swanson
Yes, I looked at it before I wrote what I did.
>> >Here is an excerpt from that meeting report;
>> >" At the end of the working conference, the majority of the particpants agreed
>> >the following points:
>> >
>> >The global environments of the last several millennia is in sharp contrast
>> >with climates that existed during most of the past million years. Warm
>> >intervals like the present one have been short lived and the natural end of
>> >our warm epoch is undoubtably near when considered on a geological
>> >time scale. Global cooling and related rapid changes of environment,
>> >substantially exceeding the fluctuations experienced by man in historical
>> >times, must be expected within the next few millennia or even centuries.
>> >In man's quest to utilise global resources, and to produce an adequate
>> >supply of food, global climate change constitutes a first order
>> >environmental hazard which must be thoroughly understood well in
>> >advance of the first global indications of deteriorating climate.
>> >Interdisciplinary attacks on these problems must be internationally
>> >organised and encouraged to develop at a rate substantially exceeding
>> >the present rate."
[cut]
>> >The problem of abrupt climate change has not gone away. The next event
>> >has got closer. Moreover we now know that the speed of these event is not
>> >millenia or centuries but in fact decades and years.
>>
>> Given the level of understanding of the day, the notion that an Ice Age begin
>> within a few millenia was not far fetched. However, the scientists of the day
>> didn't say for certain that one was GOING to occur in the immediate future.
>> Similarly, the notion that only a few years remain before major changes in
>> climate kick in is equally out of touch with the science of today. There is
>> not enough known about possible abrupt changes to say for certain WHEN the
>> next big jump will occur.
>
>Well, I think it is obvious but no one will take me seriously. When the Arctic
>ice melts there will be a large change in planetary albedo which will trigger
>a rapid change. It is the sudden formation and collapse of sea ice sheets
>which causes rapid climate change.
Not likely. There are no "sea-ice sheets", as you put it. The sea-ice changes
over a yearly cycle, with most of it melting in the Arctic and almost all of
it melting around the Antarctic. Since that is already happening, I don't
think the change in the arctic will be sudden, as there will still be sea-ice in
winter over the Arctic Ocean. Also, your presumed strong ocean sea-ice albedo
feedback is not as strong as you think. I presented a paper about the subject
some 11 years ago, in which I showed otherwise. Care to offer some real numbers
to back up your contention??
>> >.....Denying that scientists
>> >predicted an imminent ice age is pointless. That is the spin the public
>> >received. We should now concentrate in getting it across that the threat
>> >of a rapid climate change has not gone away, only it will be to a warmer
>> >state. If we come out with something so obviously true then perhaps we
>> >can persuade them there is a danger.
>>
>> From the U.K., you probably don't get blasted by the denialists who have been
>> promoting the notion that the so-called Global Cooling Scare represented a
>> failed prediction, which is then taken as an excuse to ignore the current
>> scienctific understanding about Global Warming. In a sense, the denialists
>> are heaping manure on the previous concerns about an impending Ice Age to
>> indirectly bury the newer research that points out that indeed, a return to
>> Ice Age conditions in some locations may result from Global Warming. See my
>> comment on your posting of the paper by SEAGER et al.
>
>I have two problems with that. First the scare did happen, and it was
>initiated by scientists. The public are not fools so if we deny that, we are
>only seen as liars, which makes our case worse.
Wrong. Got a reference which shows "the scientists" projecting an immediate
Ice Age future? And you are ignoring my comments regarding increasing sea-ice
in the North Atlantic as a result of THC shutdown. Note that your reference
supports this scenario.
>Second, the idea that global warming can lead to cooling is absurd, even
>if it were true. It could only work if on average there was not much warming.
>Therefore the public say to themselves "The warming cannot be that great,
>why worry." Or they say "These scientists have got their heads in the clouds.
>They are always coming up with scary stories etc. ..." This also weakens
>our case.
There is quite a bit of science which turns out to be counter intuitive.
Try again.
>I have always been skeptical about a repeat of the Younger Dryas happening
>as a result of global warming. But now I know that it is the sea ice sheets
>which trigger these events, then it is impossible. Wally Broecker has also
>changed his mind about the NADW being the trigger and now thinks it
>is sea ice. I can dig out a reference if you like.
You are confusing "ice sheet" with "sea-ice". The sea-ice is an amplifier.
Think of what happens when one pulls the trigger on a gun. The sear releases
the hammer, which is accelerated by the force of a spring and impacts a firing
pin. The firing pin accelerates rapidly, moving toward the primer. Whan the
firing pin impacts the primer, the metal is deformed, crushing a shock sensitive
explosive, which ignites. The gases which result rapidly flow thru a small hole
into the main chamber of the cartridge, igniting the powder charge. The powder
charge burns rapidly, but at a rate slow enough that the pressure in the chamber
does not become excessive. As the pressure in the cartridge increases, the bullet
begins to accelerate out the barrel. The bullet contacts the rifling and begins
to rotate. The bullet rapidly moves thru the barrel, gaining speed and spinning
faster. Finally, the bullet exits the barrel, along with most fo the gas produced
by burning the propellant. All this happens in a small fraction of a second. The
action of squeezing the trigger is amplified considerably, producing a fast moving
object in a very precisely controlled direction. Pull trigger, gun go boom.
There are many complex interactions in this simple device. Remove or change any
one of them and the result could be different. The same is true for the climate
system. The ultimate result of our ongoing climate change experiment is not nearly
as simple as you (or I) might think.
Start digging.
>The problem has been it is oceanographers who have been leading the
>charge in investigating abrupt change. Meteorology is where it happens.
>And other sciences such as paleobiology and geomorphology have
>also got a part to play.
Do you call the folks that drill ice core oceanographers?
w...@bas.ac.uk
>"Alastair McDonald" <alas...@abmcdonald.leavethisout.freeserve.co.uk>
>wrote in news:bgvt4g$uf9$1...@newsg3.svr.pol.co.uk:
>
>> "Thomas Palm" <Thoma...@chello.removethis.se> wrote in message
>> news:Xns93D177CDCEA69T...@212.83.64.229...
>>> w...@bas.ac.uk wrote in news:3f33...@news.nwl.ac.uk:
>>> > I browsed those pages. I agree they are a useful resource but they are
>>> > also somewhat disappointing in that there is very little material
>>> > direct from the references persented (unlike my pages, hurrah!).
>>>
>>> Have you sent the author a link to your page? Since it is a hypertext
>>> document it can be easily updated.
>>
>> I don't think that would be very useful. Spencer Weart has written a
>> history. Why should he be interested in William Connelly's attempt
>> to rewrite history?
I am somewhat surprised to see AM write this. What does he mean?
>They cover different subjects. Weart tries to describe history as it was,
>William is trying to debunk a specific myth about how it was supposed to
>have been. He is debunking the people trying to rewrite history.
I haven't sent the author a link to my page (feel free to do so if you like).
As Thomas Palm (in full!) says, they are different. I did feel that the
pages somewhat skate over the cooling stuff, but then I'm biased.
w...@bas.ac.uk
>Unfortuately he is not debunking a myth. There was a scare in the 70s
>about another ice age, even if it was so long ago it is only a myth to
>those of William's age.
And I'm interested in the scientific basis, or lack thereof.
>Weart identifies C.E.P.Brooks as warning of
>an abrupt climate change, long before the evidence from fossil beetles
>and ice cores was available.
Please reference things like this - its tedious expecting me to search for
things that you presumably know where they are. All I can find is
http://www.aip.org/history/climate/cycles.htm#M_5_
which hardly supports what you say.
>Moreover, Fred Hoyle also warned of this danger
Ref...
, and William now has a reference G.J. Kukla & R.K. Matthews,
>Science, 178, 190-1, 1972: but appears not to have read it.
Thats right. I've assumed its similar to:
http://www.wmc.care4free.net/sci/iceage/quat_res_1972.html
>The full text can be read at;
>http://links.jstor.org/sici?sici=0036-8075%2819721013%293%3A178%3A4057%3C190%3AWWTPIE%3E2.0.CO%3B2-Q
I don't have access to this. But I'll rip off what you've provided and add
it to my site... :-)
>Here is an excerpt from that meeting report;
>" At the end of the working conference, the majority of the particpants agreed
>the following points:
>The global environments of the last several millennia is in sharp contrast
>with climates that existed during most of the past million years. Warm
>intervals like the present one have been short lived and the natural end of
>our warm epoch is undoubtably near when considered on a geological
>time scale.
True, but near meaningless since geological timescales are so long.
>Global cooling and related rapid changes of environment,
>substantially exceeding the fluctuations experienced by man in historical
>times, must be expected within the next few millennia or even centuries.
Aha, this is more interesting! A similar quote appears in:
http://www.wmc.care4free.net/sci/iceage/quat_res_1972.html
However, the ref above quotes a far more nuanced view, which (IMHO)
was cmuch closer to the state of scientific knowledge at the time.
The Science article seems a bit "sexed up" to use a current phrase... that
of course is interesting in itself.
>In man's quest to utilise global resources, and to produce an adequate
>supply of food, global climate change constitutes a first order
>environmental hazard which must be thoroughly understood well in
>advance of the first global indications of deteriorating climate.
>Interdisciplinary attacks on these problems must be internationally
>organised and encouraged to develop at a rate substantially exceeding
>the present rate."
>Among those present at the meeting were R.G.Barry, C. Emiliana,
>J. Imbrie, W. Ruddiman, C.B.Schultz, N.J.Shackleton, and P.W. Weyl.
>Contributions were recieved from among others Broecker, Dansgaard,
>and Schneider.
>The problem of abrupt climate change has not gone away.
But they, of course, are *not* talking about "abrupt" change: they are
talking about Milankovitch 1000y (to century) type timescales.
> The next event
>has got closer. Moreover we now know that the speed of these event is not
>millenia or centuries but in fact decades and years.
No we don't.
w...@bas.ac.uk
>alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>>I have always been skeptical about a repeat of the Younger Dryas happening
>>as a result of global warming. But now I know that it is the sea ice sheets
...
>You are confusing "ice sheet" with "sea-ice". The sea-ice is an amplifier.
Sea ice sheets is certainly an odd phrase: I'm not aware of anyone else
using it. I hope that AM does know the difference between land ice,
ice shelves and sea ice.
Alastair McDonald
> > When the Arctic ice melts there will be a large change in planetary
> > albedo which will trigger a rapid change. It is the sudden formation
> > and collapse of sea ice sheets which causes rapid climate change.
>
> Not likely. There are no "sea-ice sheets", as you put it. The sea-ice
> changes over a yearly cycle, with most of it melting in the Arctic and
> almost all of it melting around the Antarctic. Since that is already
> happening, I don't think the change in the arctic will be sudden, as
> there will still be sea-ice in winter over the Arctic Ocean.
Typically the Arctic ice reduces from 15 Mkm^2 to 10 Mkm^2. See;
http://www.arctic.noaa.gov/essay_untersteiner.html
Therefore it provides a permanent sea-ice sheet of 10Mkm^2. The Weddel
Sea ice is smaller, and of course there are also ice shelfs in the
Antarctic. But it is in northern hemisphere where the rapid changes
will happen and are triggered.
> Also, your presumed strong ocean sea-ice albedo
> feedback is not as strong as you think. I presented a paper about the
> subject some 11 years ago, in which I showed otherwise. Care to
> offer some real numbers to back up your contention??
Care to let us see your paper? As far as the ice albedo feedback is concerned
I now agree with you that it probably is not important. The multi-year ice
concentration is decreasing because of warmer more saline Arctic waters.
The ice is no longer sealing in the warmer sea water from the atmosphere.
When it disappears completely the seasonal ice will not be able to
reform. The multi-year ice decreased by 10% last year and probalby
the same this. I leave it to you to work out the feedback in numbers.
> >I have two problems with that. First the scare did happen, and it was
> >initiated by scientists. The public are not fools so if we deny that,
> > we are only seen as liars, which makes our case worse.
>
> Wrong. Got a reference which shows "the scientists" projecting an immediate
> Ice Age future?
I already quoted this from Science;
"Global cooling and related rapid changes of environment, substantially
exceeding the fluctuations experienced by man in historical times, must
be expected within the next few millennia or even centuries."
If that is not immediate enough for you then tell your critics it was not
that soon, not that it was never said!
> And you are ignoring my comments regarding increasing sea-ice
> in the North Atlantic as a result of THC shutdown. Note that your reference
> supports this scenario.
The sea ice will not form if the THC shuts down unless it is
at freezing temperature, which it is not! See;
http://www.fnmoc.navy.mil/products/OTIS/US058VMET-GIFwxg.OTIS.glbl_sstanomaly.gif
> >Second, the idea that global warming can lead to cooling is absurd, even
> >if it were true. It could only work if on average there was not much
> > warming. Therefore the public say to themselves "The warming cannot
> > be that great, why worry." Or they say "These scientists have got their
> > heads in the clouds. They are always coming up with scary stories etc.
> > ..." This also weakens our case.
>
> There is quite a bit of science which turns out to be counter intuitive.
> Try again.
I am sorry but there is couter intuitive, like more snow as temperatures
increase, but there is also impossible, like snow when temperatures
are over 30C. In the current world, without a Laurentide ice sheet
and a huge source of ice cold water such as that which was in Lake
Agassiz, there is no way the Norwegian Sea will freeze.
> >I have always been skeptical about a repeat of the Younger Dryas happening
> >as a result of global warming. But now I know that it is the sea ice sheets
> >which trigger these events, then it is impossible. Wally Broecker has also
> >changed his mind about the NADW being the trigger and now thinks it
> >is sea ice. I can dig out a reference if you like.
>
> You are confusing "ice sheet" with "sea-ice". The sea-ice is an amplifier.
The effect of ice from a climate point of view is the same whether it is
land or sea ice. Sea-ice makes the sea behave as land, with a rapid cooling
and increased albedo.
What do you think sea-ice amplifies?
OK, I'll explain. Lake Agassiz is formed from melting glaciers, and is a
huge lake of fresh water at 0C. It overflows into the North Atlantic and
floats across the top of the sea where the Gulf Stream turns to flow east.
It is carried from the Gulf Steam north by the North Atlantic Drift (NAD)
and fills the Norwegian Sea which halts the Conveyor because the cold
fresh water is insulating the salty water from the cold air. Without the
warmth from the NAD, Norway and Scotland become cooler
and small ice sheets form on them. This increase in albedo is enough to
form permanent ice on the Norwegian and Greenland Seas which also
collect snow which increases albedo further lowering local temperatures.
The sea-ice sheet cools the atmosphere, not only by sealing in the warmer
ocean, but also by radiating heat away and allowing the surface temperature
to drop well below zero, something liquid water cannot do. This reduces
the water vapour in the air, because the ice evaporates less but also cools.
The lack of water vapour in the air causes further cooling because of the
lack of greenhouse effect from the water vapour. It is this positive feedback
from cold air reducing evaporation which reduces the greenhouse effect
from water vapour giving furthere cooling that causes abrupt climate change.
HTH,
Cheers, Alastair.
from the
triggers a rapid cooling.
Eric Swanson
>
>
>"Eric Swanson" <swanson@nospam_on.net> wrote in message
>news:bh37o1$4fpu$1...@news3.infoave.net...
>
>> > When the Arctic ice melts there will be a large change in planetary
>> > albedo which will trigger a rapid change. It is the sudden formation
>> > and collapse of sea ice sheets which causes rapid climate change.
>>
>> Not likely. There are no "sea-ice sheets", as you put it. The sea-ice
>> changes over a yearly cycle, with most of it melting in the Arctic and
>> almost all of it melting around the Antarctic. Since that is already
>> happening, I don't think the change in the arctic will be sudden, as
>> there will still be sea-ice in winter over the Arctic Ocean.
>
>Typically the Arctic ice reduces from 15 Mkm^2 to 10 Mkm^2. See;
>http://www.arctic.noaa.gov/essay_untersteiner.html
>Therefore it provides a permanent sea-ice sheet of 10Mkm^2. The Weddel
>Sea ice is smaller, and of course there are also ice shelfs in the
>Antarctic. But it is in northern hemisphere where the rapid changes
>will happen and are triggered.
The sea-ice which remains in the Arctic Ocean at the end of the melt season
is not "permanent", as it moves around quite a bit. The location of the
multi-year sea-ice changes from year to year.
>> Also, your presumed strong ocean sea-ice albedo
>> feedback is not as strong as you think. I presented a paper about the
>> subject some 11 years ago, in which I showed otherwise. Care to
>> offer some real numbers to back up your contention??
>
>Care to let us see your paper?
Sorry, Troll, I'm not going to do your homework for you. My paper wasn't
peer reviewed and there has been other work published since.
>.............As far as the ice albedo feedback is concerned
>I now agree with you that it probably is not important. The multi-year ice
>concentration is decreasing because of warmer more saline Arctic waters.
>The ice is no longer sealing in the warmer sea water from the atmosphere.
>When it disappears completely the seasonal ice will not be able to
>reform. The multi-year ice decreased by 10% last year and probalby
>the same this. I leave it to you to work out the feedback in numbers.
I would expect that there would always be some sea-ice formation during winter
in the Arctic Ocean. After all, there isn't any solar energy input to the
North Pole for 6 months of the year. As I pointed out in another post, there
appears to be a bit more sea-ice this year than last year. Look at the winter
(JFM) sea-ice extent from Figure 1 of your reference to Untersteiner's note.
Hardly any change can be seen in winter extent.
>> >I have two problems with that. First the scare did happen, and it was
>> >initiated by scientists. The public are not fools so if we deny that,
>> > we are only seen as liars, which makes our case worse.
>>
>> Wrong. Got a reference which shows "the scientists" projecting an immediate
>> Ice Age future?
>
>I already quoted this from Science;
>"Global cooling and related rapid changes of environment, substantially
>exceeding the fluctuations experienced by man in historical times, must
>be expected within the next few millennia or even centuries."
>
>If that is not immediate enough for you then tell your critics it was not
>that soon, not that it was never said!
No, to me, 5 - 100 years is "immediate". Several thousand years could be a the
normal Milankovitch change.
>> And you are ignoring my comments regarding increasing sea-ice
>> in the North Atlantic as a result of THC shutdown. Note that your reference
>> supports this scenario.
>
>The sea ice will not form if the THC shuts down unless it is
>at freezing temperature, which it is not! See;
>http://www.fnmoc.navy.mil/products/OTIS/US058VMET-GIFwxg.OTIS.glbl_sstanomaly.gif
The graph is of the present anomaly, not the minimum temperatures at the coldest
time of the year. Anomalies are not absolute temperatures. The surface temperatures
vary through out the year. The water which presently sinks and forms the NADW is
very close to the freezing point. It's at that temperature because that's the point
at which the density is great enough for the sinking to occur. The salinity is less
than that seen further south, due to a net transfer of water to higher latitudes by
atmospheric circulation. Sea-ice does occur over portions of the Nordic Seas every
year. A relatively small increase in fresh water entering the North Atlantic would
stop the THC sinking, because the density would not be great enough, even as the
surface water cools to freezing.
>> >Second, the idea that global warming can lead to cooling is absurd, even
>> >if it were true. It could only work if on average there was not much
>> > warming. Therefore the public say to themselves "The warming cannot
>> > be that great, why worry." Or they say "These scientists have got their
>> > heads in the clouds. They are always coming up with scary stories etc.
>> > ..." This also weakens our case.
>>
>> There is quite a bit of science which turns out to be counter intuitive.
>> Try again.
>
>I am sorry but there is couter intuitive, like more snow as temperatures
>increase, but there is also impossible, like snow when temperatures
>are over 30C. In the current world, without a Laurentide ice sheet
>and a huge source of ice cold water such as that which was in Lake
>Agassiz, there is no way the Norwegian Sea will freeze.
Happens in some places every year NOW. Care to consider what happened during
the Little Ice Age?? It was cold enough for the Baltic to freeze. There was
said to be a considerable expansion of sea-ice around Iceland.
>> >I have always been skeptical about a repeat of the Younger Dryas happening
>> >as a result of global warming. But now I know that it is the sea ice sheets
>> >which trigger these events, then it is impossible. Wally Broecker has also
>> >changed his mind about the NADW being the trigger and now thinks it
>> >is sea ice. I can dig out a reference if you like.
>>
>> You are confusing "ice sheet" with "sea-ice". The sea-ice is an amplifier.
>
>The effect of ice from a climate point of view is the same whether it is
>land or sea ice. Sea-ice makes the sea behave as land, with a rapid cooling
>and increased albedo.
>
>What do you think sea-ice amplifies?
No it doesn't. Sea-ice is transient, since it doesn't last all year.
I think the definition of "ice sheet" implies persistent land ice.
Got that reference to Broecker's thoughts yet?
[cut]
>>The ultimate result of our ongoing climate change experiment is not nearly
>> as simple as you (or I) might think.
>
>OK, I'll explain. Lake Agassiz is formed from melting glaciers, and is a
>huge lake of fresh water at 0C. It overflows into the North Atlantic and
>floats across the top of the sea where the Gulf Stream turns to flow east.
>It is carried from the Gulf Steam north by the North Atlantic Drift (NAD)
>and fills the Norwegian Sea which halts the Conveyor because the cold
>fresh water is insulating the salty water from the cold air.
Except that the surface water exists in a well mixed layer, which results
from wind forces. The amount of water in the top 50 to 100 meters is what
one should be looking at. Besides, there is no Lake Agassiz today.
>..........Without the
>warmth from the NAD, Norway and Scotland become cooler
>and small ice sheets form on them. This increase in albedo is enough to
>form permanent ice on the Norwegian and Greenland Seas which also
>collect snow which increases albedo further lowering local temperatures.
>The sea-ice sheet cools the atmosphere, not only by sealing in the warmer
>ocean, but also by radiating heat away and allowing the surface temperature
>to drop well below zero, something liquid water cannot do. This reduces
>the water vapour in the air, because the ice evaporates less but also cools.
>The lack of water vapour in the air causes further cooling because of the
>lack of greenhouse effect from the water vapour. It is this positive feedback
>from cold air reducing evaporation which reduces the greenhouse effect
>from water vapour giving furthere cooling that causes abrupt climate change.
I think you are getting it. I don't think the presence of sea-ice over the
Nordic Seas would be year round though, at least not at first. That sea-ice
ocean albedo difference is stronger at more southern latitudes, compared to
that of the Arctic Ocean.
w...@bas.ac.uk
>alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>>I already quoted this from Science;
>>"Global cooling and related rapid changes of environment, substantially
>>exceeding the fluctuations experienced by man in historical times, must
>>be expected within the next few millennia or even centuries."
>No, to me, 5 - 100 years is "immediate". Several thousand years could be a
>the normal Milankovitch change.
Well, it could be because it is. Thats where the phrase comes from. Note,
BTW, that this was from a meeting report, not a paper, and thus *probably*
escaped peer review.
Alastair McDonald
> Eric Swanson <swanson> wrote:
> >alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>
> >>I already quoted this from Science;
>
> >>"Global cooling and related rapid changes of environment, substantially
> >>exceeding the fluctuations experienced by man in historical times, must
> >>be expected within the next few millennia or even centuries."
>
> >No, to me, 5 - 100 years is "immediate". Several thousand years could be a
> >the normal Milankovitch change.
>
> Well, it could be because it is. Thats where the phrase comes from. Note,
They did say centuries, and don't forget they are conservative scientists.
They won't say decades even if it is a possiblity, unless they can prove
it despite, it being what they believed.
> BTW, that this was from a meeting report, not a paper, and thus *probably*
> escaped peer review.
Aren't you splitting hairs now? It was published in a peer reviewed journal,
probably the most influencial, and summarised the discussions of the very
people who would do the peer reviewing.
The point is that this meeting was the beginning of scientists realising that
the climate behaves abruptly, long before they had the evidence from ice
cores. They were right! An abrupt climate change will happen soon. It is
just that they said it would be colder. It has already started and it is
hotter.
Cheers, Alastair.
Alastair McDonald
"Eric Swanson" <swanson@nospam_on.net> wrote in message
news:bhj1t9$ecu0$1...@news3.infoave.net...
> In article <bhior8$7dn$1...@newsg2.svr.pol.co.uk>,
alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>
> The sea-ice which remains in the Arctic Ocean at the end of the melt season
> is not "permanent", as it moves around quite a bit. The location of the
> multi-year sea-ice changes from year to year.
My COD defines "permanent" as "lasting".
> I would expect that there would always be some sea-ice formation during
> winter in the Arctic Ocean. After all, there isn't any solar energy input
> to the North Pole for 6 months of the year.
The problem with that reasoning is that you are ignoring the difference
between a sea-ice sheet, sea ice, and open water. A sea-ice sheet seals
in the heat of the ocean because it has few leads especially in winter.
Sea ice allows the heat from the ocean to escape, but open sea, when
it cools, sinks and allows warmer sea from beneath to the surface
preventing freezing. Without the cold air from the multiyear ice,
which has radiated its surface heat away, then the air will not be
cold enough to freeze the sea surface. In the ice forming season,
the new ice surface provides a positive feedback helping create
more ice. Without a core of permanent ice at the start of the
season, the ice will not expand.
> As I pointed out in another post, there
> appears to be a bit more sea-ice this year than last year.
I am not sure where you are looking to see more sea-ice this year. I
hope it is not Robert Grumbine's site. The current ice there has not
been updated since the 4th August. So you will be comparing
the ice last year with that then, nearly a fortnight earlier.
> Look at the winter
> (JFM) sea-ice extent from Figure 1 of your reference to Untersteiner's note.
> Hardly any change can be seen in winter extent.
The winter extent is set by the temperature at the margin. The positive
feedback effect of sea ice growth will extend the ice out to this margin,
provided the summer area is large enough to spawn the process.
> >I already quoted this from Science;
> >"Global cooling and related rapid changes of environment, substantially
> >exceeding the fluctuations experienced by man in historical times, must
> >be expected within the next few millennia or even centuries."
> >
> >If that is not immediate enough for you then tell your critics it was not
> >that soon, not that it was never said!
>
> No, to me, 5 - 100 years is "immediate". Several thousand years could be a
> the normal Milankovitch change.
Well, I was referring to centuries not millennia. However, I will answer
William's post since this is now a separate issue.
> The graph is of the present anomaly, not the minimum temperatures at the
> coldest time of the year. Anomalies are not absolute temperatures. The
> surface temperatures vary through out the year. The water which presently
> sinks and forms the NADW is very close to the freezing point.
Hence the anomally is showing the temperature above freezing point.
> It's at that temperature because that's the point
> at which the density is great enough for the sinking to occur. The salinity
> is less than that seen further south, due to a net transfer of water to
higher
> latitudes by atmospheric circulation. Sea-ice does occur over portions of
> the Nordic Seas every year. A relatively small increase in fresh water
> entering the North Atlantic would stop the THC sinking, because the
> density would not be great enough, even as the surface water cools to
> freezing.
If that happened and the North Atlantic cooled it would freeze again. A
relatively small increase in fresh water would allow the system to
readjust itself. Only a large flow of water, such as that from Lake
Agassiz can stop the THC.
> >I am sorry but there is couter intuitive, like more snow as temperatures
> >increase, but there is also impossible, like snow when temperatures
> >are over 30C. In the current world, without a Laurentide ice sheet
> >and a huge source of ice cold water such as that which was in Lake
> >Agassiz, there is no way the Norwegian Sea will freeze.
>
> Happens in some places every year NOW. Care to consider what happened
> during the Little Ice Age?? It was cold enough for the Baltic to freeze.
> There was said to be a considerable expansion of sea-ice around Iceland.
The Greenland and Baltic Seas freeze, but not the Norwegian Sea, and
the cases you cite were caused by a lack of solar energy, not an increase
in greenhouse gasses which is what you are postulating.
Besides the whole point of Occam's razor is to counter counter intuitivity!
> > Sea-ice makes the sea behave as land, with a rapid cooling
> >and increased albedo.
> No it doesn't. Sea-ice is transient, since it doesn't last all year.
> I think the definition of "ice sheet" implies persistent land ice.
OK, what I mean by the term sea-ice sheet is an area of floating ice
consisting to two main types. There is seasonal ice which is
similar to your sea ice, and there is permanent ice which includes
first year and multi-year ice. During winter the permanent ice
and some of the seasonal ice freezes solid and then behaves
climatologically like a land ice sheet.
> Got that reference to Broecker's thoughts yet?
>
> [cut]
>
> Except that the surface water exists in a well mixed layer, which results
> from wind forces. The amount of water in the top 50 to 100 meters is what
> one should be looking at. Besides, there is no Lake Agassiz today.
For the air tempererature over the open ocean to drop below freezing all 50
to 100 meters of water must cool. For air temperatures over a sea ice sheet
to go below zero, only the first centimeter of the ice has to cool. That is
why the Arctic will not freeze without permanet ice to seed it.
> I think you are getting it. I don't think the presence of sea-ice over the
> Nordic Seas would be year round though, at least not at first. That sea-ice
> ocean albedo difference is stronger at more southern latitudes, compared to
> that of the Arctic Ocean.
You are right that the sea-ice over the Nordic Seas was not year round at
first. There is evidence from "hummocky moraines" in the Highlands of
Scotland that at first an ice sheet reformed from snow. Later, the new ice
sheet sublimed, implying a very dry cold climate. This is where I got the
idea that it is the greenhouse effect of water vapour which causes the
runaways and abrupt cooling.
The entry into the Younger Dryas was relatively slow (centuries), whereas
the exit was sudden (decades or years). This would mean that (sea) ice
sheets grow slowly, but collapse quickly. Hence the Arctic ice sheet could
disappear quickly too, you might even use the term 'immediate'!
Cheers, Alastair.
Eric Swanson
alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>
>I have pruned quite a lot. I hope without distorting anything.
I dumped quite a bit more, most of which was distortion.....
>"Eric Swanson" <swanson@nospam_on.net> wrote
>>alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>>
>> The sea-ice which remains in the Arctic Ocean at the end of
>> the melt season is not "permanent", as it moves around quite a
>> bit. The location of the multi-year sea-ice changes from
>> year to year.
>
>My COD defines "permanent" as "lasting".
Does your definition allow for major motion?
>> I would expect that there would always be some sea-ice
>> formation during winter in the Arctic Ocean. After all, there
>> isn't any solar energy input to the North Pole for 6 months
>> of the year.
>
>The problem with that reasoning is that you are ignoring the
>difference between a sea-ice sheet, sea ice, and open water. A
> sea-ice sheet seals in the heat of the ocean because it has few
> leads especially in winter. Sea ice allows the heat from the
> ocean to escape, but open sea, when it cools, sinks and allows
> warmer sea from beneath to the surface preventing freezing.
> Without the cold air from the multiyear ice, which has radiated
> its surface heat away, then the air will not be cold enough to
> freeze the sea surface. In the ice forming season, the new ice
> surface provides a positive feedback helping create more ice.
> Without a core of permanent ice at the start of the season, the
> ice will not expand.
Present understanding points to the Nordic Seas and the Labrador
Sea as the place where the sinking occurs in the North Atlantic.
The sinking water is replaced by warmer water which flows into
the area from further south. Your contention that it's just a
local vertical change, with warmer water coming from below the
surface water completely ignores the THC. Your scenario of no
Arctic sea-ice at the end of the freeze season is highly unlikely
to occur. However, the loss of all the sea-ice at the end of the
melt season is plausible and appears to be ongoing. Once the
sea-ice "cork" is removed from the Fram Strait, a large change IS
likely to occur. Your notion that the atmosphere above the
sea-ice is cooled only by the ice below ignores basic physics.
>> As I pointed out in another post, there
>> appears to be a bit more sea-ice this year than last year.
>
> I am not sure where you are looking to see more sea-ice this
> year. I hope it is not Robert Grumbine's site. The current ice
> there has not been updated since the 4th August. So you will be
> comparing the ice last year with that then, nearly a fortnight
> earlier.
Yes, I noticed a drop out in data a while back. I thought the
data flow had resumed. I went web fishing to fine an
explanation, but was not successful.
>> Look at the winter (JFM) sea-ice extent from Figure 1 of your
>> reference to Untersteiner's note.
>> Hardly any change can be seen in winter extent.
>
> The winter extent is set by the temperature at the margin. The
> positive feedback effect of sea ice growth will extend the ice
> out to this margin, provided the summer area is large enough to
> spawn the process.
Mental models and scenario building can be a great way to spend
an afternoon while downing a few brews at the pub, but eventually
any such scenario must be reconciled with known science. Yours
doesn't pass muster, in my opinion.
FYI, Untersteiner has been building models of sea-ice for a
several decades. Why don't you ask him (if he is still at it)??
w...@bas.ac.uk
>alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>>My COD defines "permanent" as "lasting".
>Does your definition allow for major motion?
The ice cover is permanent, but individual ice floes aren't.
w...@bas.ac.uk
><w...@bas.ac.uk> wrote in message news:3f3d...@news.nwl.ac.uk...
>> Well, it could be because it is. Thats where the phrase comes from. Note,
>They did say centuries, and don't forget they are conservative scientists.
They said millenia to centuries or somesuch.
>They won't say decades even if it is a possiblity, unless they can prove
>it despite, it being what they believed.
This seems unlikely, since they couldn't prove the millenia to centuries
claim either.
>> BTW, that this was from a meeting report, not a paper, and thus *probably*
>> escaped peer review.
>Aren't you splitting hairs now? It was published in a peer reviewed journal,
To some extent. But, it was published in a journal that publishes mostly
peer-reviewed papers: that doesn't mean that this report was PR's.
>probably the most influencial, and summarised the discussions of the very
No, surely Nature is! Show some patriotism, dammit.
>people who would do the peer reviewing.
Ah, well, maybe it did, maybe it didn't. See my page on the Kukla quat res.
>The point is that this meeting was the beginning of scientists realising that
>the climate behaves abruptly,
I think you are misinterpreting them. This is the beginning of them starting
to have god timing info for previous ice ages. Did you quote something from
them about abruptness?
Eric Swanson
>
>Eric Swanson <swanson> wrote:
>>alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>
>>>My COD defines "permanent" as "lasting".
>
>>Does your definition allow for major motion?
>
>The ice cover is permanent, but individual ice floes aren't.
If the trend continues and all the sea-ice melts at some future
data, then the idea of a "permanent" ice cover will be wrong.
Remember not too long ago when an ice breaker went to the North Pole
and reported minimal sea-ice along the way?
Alastair McDonald
I was not writing about NADW formation. The sites you describe
are not permanently covered with ice. I was describing the way
that the permanent ice in the Arctic Ocean affects the climate.
> Your scenario of no
> Arctic sea-ice at the end of the freeze season is highly unlikely
> to occur. However, the loss of all the sea-ice at the end of the
> melt season is plausible and appears to be ongoing. Once the
> sea-ice "cork" is removed from the Fram Strait, a large change IS
> likely to occur. Your notion that the atmosphere above the
> sea-ice is cooled only by the ice below ignores basic physics.
That sea ice affects the climate in the same way as continental
surfaces is both scientifically well known and obvious. Ice is
a solid just like rock.
> >> Look at the winter (JFM) sea-ice extent from Figure 1 of your
> >> reference to Untersteiner's note.
> >> Hardly any change can be seen in winter extent.
> >
> > The winter extent is set by the temperature at the margin. The
> > positive feedback effect of sea ice growth will extend the ice
> > out to this margin, provided the summer area is large enough to
> > spawn the process.
>
> Mental models and scenario building can be a great way to spend
> an afternoon while downing a few brews at the pub, but eventually
> any such scenario must be reconciled with known science. Yours
> doesn't pass muster, in my opinion.
>
> FYI, Untersteiner has been building models of sea-ice for a
> several decades. Why don't you ask him (if he is still at it)??
Good suggestion. The problem is that I will have to change my
writing style. Being provocative is fine in a news group. It gets
a response. It does not seem to work with respected academics!
Cheers, Alastair.
Eric Swanson
[cut]
The sea-ice over the Arctic at any one location is not "permanent'>
It may be multi-year ice, but that is not always true. Out of
curiosity, what is the difference in temperature between the water
beneath the Arctic sea-ice and the open water in leads or polynias?
>> Your scenario of no
>> Arctic sea-ice at the end of the freeze season is highly unlikely
>> to occur. However, the loss of all the sea-ice at the end of the
>> melt season is plausible and appears to be ongoing. Once the
>> sea-ice "cork" is removed from the Fram Strait, a large change IS
>> likely to occur. Your notion that the atmosphere above the
>> sea-ice is cooled only by the ice below ignores basic physics.
>
>That sea ice affects the climate in the same way as continental
>surfaces is both scientifically well known and obvious. Ice is
>a solid just like rock.
But the sea-ice may only be a few meters thick. Thus, wind stresses
cause it to shift, opening cracks and causing pressure ridges. Studies
have shown that the ice migrates over large distances around the
Arctic Ocean over time. It is not in any way like rock, which does
not move, for all practical purposes, except at fault zones.
>> >> Look at the winter (JFM) sea-ice extent from Figure 1 of your
>> >> reference to Untersteiner's note.
>> >> Hardly any change can be seen in winter extent.
>> >
>> > The winter extent is set by the temperature at the margin. The
>> > positive feedback effect of sea ice growth will extend the ice
>> > out to this margin, provided the summer area is large enough to
>> > spawn the process.
>>
>> Mental models and scenario building can be a great way to spend
>> an afternoon while downing a few brews at the pub, but eventually
>> any such scenario must be reconciled with known science. Yours
>> doesn't pass muster, in my opinion.
>>
>> FYI, Untersteiner has been building models of sea-ice for a
>> several decades. Why don't you ask him (if he is still at it)??
>
>Good suggestion. The problem is that I will have to change my
>writing style. Being provocative is fine in a news group. It gets
>a response. It does not seem to work with respected academics!
Being provocative is OK, if one is correctly presenting facts and
data. In your case, the errors are obvious to everyone but you,
starting with your lack of understanding of the heat flow situation
at the North Pole. Hey, I've seen lakes freeze overnight in winter
at latitudes around 35 degrees. At latitudes near 90 degrees, with
no solar energy inpur for almost 6 months of the year, it is totally
absurd to suggest that the Arctic Ocean might remain free of sea-ice.
Unless, of course, there really is a runaway Greenhouse Effect, in
which case, humanity will be fried or boiled or fighting over the
newly exposed lands of Antarctica.
Alastair McDonald
> In article <bhst49$gt8$1...@news7.svr.pol.co.uk>,
alas...@abmcdonald.leavethisout.freeserve.co.uk says...
> >
> >
> >"Eric Swanson" <swanson@nospam_on.net> wrote in message
> >> alas...@abmcdonald.leavethisout.freeserve.co.uk says...
> [cut]
> >I was not writing about NADW formation. The sites you describe
> >are not permanently covered with ice. I was describing the way
> >that the permanent ice in the Arctic Ocean affects the climate.
>
> The sea-ice over the Arctic at any one location is not "permanent'>
> It may be multi-year ice, but that is not always true. Out of
> curiosity, what is the difference in temperature between the water
> beneath the Arctic sea-ice and the open water in leads or polynias?
There is no difference in the water temperature. It is all at -2C, the
freezing temperture of sea water.
> >That sea ice affects the climate in the same way as continental
> >surfaces is both scientifically well known and obvious. Ice is
> >a solid just like rock.
>
> But the sea-ice may only be a few meters thick. Thus, wind stresses
> cause it to shift, opening cracks and causing pressure ridges. Studies
> have shown that the ice migrates over large distances around the
> Arctic Ocean over time. It is not in any way like rock, which does
> not move, for all practical purposes, except at fault zones.
The point is that it insulates the air from the water under the ice,
allowing air temperatures to fall to -20C or lower. Ice, like rock,
is a bad convector of heat so that its upper surface temperature can
quickly drop while its lower surface remains at the melting point
of sea ice.
You seem to be hung up on the concept that permanent ice should
not move. Permanent ice moves as you have described, it just
does not melt within one season, ie. it is permanent as opposed to
seasonal.
> Being provocative is OK, if one is correctly presenting facts and
> data. In your case, the errors are obvious to everyone but you,
> starting with your lack of understanding of the heat flow situation
> at the North Pole. Hey, I've seen lakes freeze overnight in winter
> at latitudes around 35 degrees. At latitudes near 90 degrees, with
> no solar energy inpur for almost 6 months of the year, it is totally
> absurd to suggest that the Arctic Ocean might remain free of sea-ice.
There is are two differences between lakes and seas. First, seas are
salty, and the salt inhibits freezing. As the sea water freezes it
rejects the salt making the water beneath more saline and so less
able to freeze. More importantly the second point is that seas are
deeper than lakes. Until the temperature of water drops below 4C
the cold water will sink and be replaced by warmer water from
below. Therefore in order to freeze a lake the whole lake must be
cooled to less than 4C. When that happpens the cold water will
remain on the surface and the thin surface can easily be frozen.
Sea water does not have a temperature of maximum density,
therefore in theory, the whole Arctic basin would have to be
cooled to freezing temperature before ice can be formed. Of
course, when it does freeze and later thaw it creates a surface
layer of fresh water but this is easily destroyed by storms.
> Unless, of course, there really is a runaway Greenhouse Effect, in
> which case, humanity will be fried or boiled or fighting over the
> newly exposed lands of Antarctica.
The first step will be a return the climate of the Eemian when the
Arctic Ocean was ice free but the Antarctic was still ice covered.
Cheers, Alastair.
Eric Swanson
>
>
>"Eric Swanson" <swanson@nospam_on.net> wrote in message
>alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>> >"Eric Swanson" <swanson@nospam_on.net> wrote in message
>> >> alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>> [cut]
>
>> >I was not writing about NADW formation. The sites you describe
>> >are not permanently covered with ice. I was describing the way
>> >that the permanent ice in the Arctic Ocean affects the climate.
>>
>> The sea-ice over the Arctic at any one location is not "permanent"
>> It may be multi-year ice, but that is not always true. Out of
>> curiosity, what is the difference in temperature between the water
>> beneath the Arctic sea-ice and the open water in leads or polynias?
>
>There is no difference in the water temperature. It is all at -2C, the
>freezing temperture of sea water.
So water exposed to the air at leads or polynias during winter tends to
freeze rather quickly, right?
>> >That sea ice affects the climate in the same way as continental
>> >surfaces is both scientifically well known and obvious. Ice is
>> >a solid just like rock.
>>
>> But the sea-ice may only be a few meters thick. Thus, wind stresses
>> cause it to shift, opening cracks and causing pressure ridges. Studies
>> have shown that the ice migrates over large distances around the
>> Arctic Ocean over time. It is not in any way like rock, which does
>> not move, for all practical purposes, except at fault zones.
>
>The point is that it insulates the air from the water under the ice,
>allowing air temperatures to fall to -20C or lower. Ice, like rock,
>is a bad convector of heat so that its upper surface temperature can
>quickly drop while its lower surface remains at the melting point
>of sea ice.
The thickness of sea-ice is a function of the thermal characteristics
of ice. Thinner ice grows by freezing at the water/ice intersection.
The heat flow to the colder atmosphere above and the infrared emission
to the night sky removes the heat to cause the freezing. As the
thickness increases, the heat transfer rate slows until little new ice
may be added. From then on, the ice acts as an insulator, not before.
>You seem to be hung up on the concept that permanent ice should
>not move. Permanent ice moves as you have described, it just
>does not melt within one season, ie. it is permanent as opposed to
>seasonal.
No, I think one should be careful about the difference between a
"permanent ice sheet" over land and multi-year sea-ice.
>> Being provocative is OK, if one is correctly presenting facts and
>> data. In your case, the errors are obvious to everyone but you,
>> starting with your lack of understanding of the heat flow situation
>> at the North Pole. Hey, I've seen lakes freeze overnight in winter
>> at latitudes around 35 degrees. At latitudes near 90 degrees, with
>> no solar energy inpur for almost 6 months of the year, it is totally
>> absurd to suggest that the Arctic Ocean might remain free of sea-ice.
>
>There is are two differences between lakes and seas. First, seas are
>salty, and the salt inhibits freezing. As the sea water freezes it
>rejects the salt making the water beneath more saline and so less
>able to freeze. More importantly the second point is that seas are
>deeper than lakes. Until the temperature of water drops below 4C
>the cold water will sink and be replaced by warmer water from
>below. Therefore in order to freeze a lake the whole lake must be
>cooled to less than 4C. When that happpens the cold water will
>remain on the surface and the thin surface can easily be frozen.
>Sea water does not have a temperature of maximum density,
>therefore in theory, the whole Arctic basin would have to be
>cooled to freezing temperature before ice can be formed. Of
>course, when it does freeze and later thaw it creates a surface
>layer of fresh water but this is easily destroyed by storms.
In the Arctic Ocean, if the column of water is at nearly freezing to
begin with (as it is now), the surface can quickly freeze, once the
air temperature drops below freezing. I was just pointing out again
the fact that there is almost no possibility of the Arctic Ocean
being ice free year round.
>> Unless, of course, there really is a runaway Greenhouse Effect, in
>> which case, humanity will be fried or boiled or fighting over the
>> newly exposed lands of Antarctica.
>
>The first step will be a return the climate of the Eemian when the
>Arctic Ocean was ice free.......
Ok, guy, give us a reference for that statement.
Ice free at the end of the melt season is not the same as
completely free of sea-ice year round.
Alastair McDonald
> In article <bhteo6$b8i$1...@newsg1.svr.pol.co.uk>,
alas...@abmcdonald.leavethisout.freeserve.co.uk says...
> >There is no difference in the water temperature. It is all at -2C, the
> >freezing temperture of sea water.
>
> So water exposed to the air at leads or polynias during winter tends to
> freeze rather quickly, right?
At leads, yes! At polynyas, no (by definition.) The last I heard was that
the polynya that forms in the Weddell Sea was the result of deep ocean
currents passing over a sea bed obstacle and lifting deeper water to the
surface. I am not sure whether the deep water was saltier or warmer
than the surface water.
> >> >That sea ice affects the climate in the same way as continental
> >> >surfaces is both scientifically well known and obvious. Ice is
> >> >a solid just like rock.
> >>
> >> But the sea-ice may only be a few meters thick. Thus, wind stresses
> >> cause it to shift, opening cracks and causing pressure ridges. Studies
> >> have shown that the ice migrates over large distances around the
> >> Arctic Ocean over time. It is not in any way like rock, which does
> >> not move, for all practical purposes, except at fault zones.
> >
> >The point is that it insulates the air from the water under the ice,
> >allowing air temperatures to fall to -20C or lower. Ice, like rock,
> >is a bad convector of heat so that its upper surface temperature can
> >quickly drop while its lower surface remains at the melting point
> >of sea ice.
>
> The thickness of sea-ice is a function of the thermal characteristics
> of ice. Thinner ice grows by freezing at the water/ice intersection.
> The heat flow to the colder atmosphere above and the infrared emission
> to the night sky removes the heat to cause the freezing. As the
> thickness increases, the heat transfer rate slows until little new ice
> may be added. From then on, the ice acts as an insulator, not before.
That will apply to all permanent ice, as it has already reached its
maximum thickness.
> >You seem to be hung up on the concept that permanent ice should
> >not move. Permanent ice moves as you have described, it just
> >does not melt within one season, ie. it is permanent as opposed to
> >seasonal.
>
> No, I think one should be careful about the difference between a
> "permanent ice sheet" over land and multi-year sea-ice.
Oh! I am not saying they are the same. Ice sheets feed glaciers
and ice shelves, both of which can produce icebergs. Sea-ice
sheets only calve sea ice. There are one and a half sea-ice
sheets in the world today, so they are pretty rare, perhaps that
is why you are unaware of them. They are the Arctic Ocean
sea-ice sheet and the Weddell Sea sea-ice sheet.
BTW a sea-ice sheet consists of two parts; seasonal ice and
permanent ice. The permanent ice is made up of first year ice and
multi-year ice. Therefore multi-year ice and permanent ice are
not equivalent.
> In the Arctic Ocean, if the column of water is at nearly freezing to
> begin with (as it is now), the surface can quickly freeze, once the
> air temperature drops below freezing. I was just pointing out again
> the fact that there is almost no possibility of the Arctic Ocean
> being ice free year round.
It is at freezing now because the (seasonal) ice is melting. Therefore
sea and air temperature cannot climb above 0C. Once all the ice
melts, then the sea temperatures can rise above zero and make it
more difficult for the sea to refreeze.
> Ok, guy, give us a reference for that statement.
> Ice free at the end of the melt season is not the same as
> completely free of sea-ice year round.
Chapter 1 of Brooks, C.E.P. (1949). Climate through the Ages: A Study of the
Climatic Factors and Their Variations (Rev. Ed.). London: Benn.
HTH,
Cheers, Alastair.
Robert Grumbine
Alastair McDonald <alas...@abmcdonald.leavethisout.freeserve.co.uk> wrote:
>I have pruned quite a lot. I hope without distorting anything.
>
>"Eric Swanson" <swanson@nospam_on.net> wrote in message
>news:bhj1t9$ecu0$1...@news3.infoave.net...
>> In article <bhior8$7dn$1...@newsg2.svr.pol.co.uk>,
>alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>>
>> I would expect that there would always be some sea-ice formation during
>> winter in the Arctic Ocean. After all, there isn't any solar energy input
>> to the North Pole for 6 months of the year.
>
>The problem with that reasoning is that you are ignoring the difference
>between a sea-ice sheet, sea ice, and open water. A sea-ice sheet seals
>in the heat of the ocean because it has few leads especially in winter.
The term is ice pack or sea ice pack. It never forms a sheet (a term
which implies that it is unbroken, and the ice pack is always broken in
to ice floes).
>Sea ice allows the heat from the ocean to escape, but open sea, when
>it cools, sinks and allows warmer sea from beneath to the surface
>preventing freezing. Without the cold air from the multiyear ice,
>which has radiated its surface heat away, then the air will not be
>cold enough to freeze the sea surface. In the ice forming season,
>the new ice surface provides a positive feedback helping create
>more ice. Without a core of permanent ice at the start of the
>season, the ice will not expand.
Present a quantitative argument demonstrating that and you've
got a publishable paper. There's no quantitative reason yet to
believe that water won't freeze in the arctic winter for a good
long time into the future (speaking minimally: decades).
[snip]
>I am not sure where you are looking to see more sea-ice this year. I
>hope it is not Robert Grumbine's site. The current ice there has not
>been updated since the 4th August. So you will be comparing
>the ice last year with that then, nearly a fortnight earlier.
As I'll be posting shortly, there were some problems. Some of them
involved and involve fairly upper management. The immediate problems,
i.e., those not involving fairly upper management, are now fixed.
[snip]
>For the air tempererature over the open ocean to drop below freezing all 50
>to 100 meters of water must cool. For air temperatures over a sea ice sheet
>to go below zero, only the first centimeter of the ice has to cool. That is
>why the Arctic will not freeze without permanet ice to seed it.
What is impossible about cooling 50 meters (by the way, it's more like 25
meters over much of the Arctic) of water by 1 C (water's already about -1 in
a goodly volume of the Arctic) in a 6 month winter without sun? Please
be quantitative.
As a start, the heat capacity of a slab of ocean that is H meters thick is
rho*c_p*H. rho = density of sea water, about 1025 kg/m^3, and c_p is the
specific heat, about 4000 J/kg. For 25 meters, this is about 1e8 J/m^2.
The sun, on global average (and after albedo) supplies about 250 W/m^2.
Taking that as the magnitude of the winter time heat deficit gives
(1e8 / 250) seconds, or under 5 days.
Remember too that Siberia is not far from the Arctic and can be counted
on to produce cold air for much the same reasons it does now. If the
Arctic tried to be warm (ice free), I expect (intuitively) that the
cold air would find its way to the Arctic. (It tends to already).
You might be right about the loss of an ice pack in the summertime
causing no ice pack to form in the winter either. But you'll have
to present something stronger than the fact that you think so to
persuade anyone. Allusions to 50 meters vs. 1 cm are a start, but
it's going to take something at least as substantial as my back of
the envelope above to be convincing.
[snip]
--
Robert Grumbine http://www.radix.net/~bobg/ Science faqs and amateur activities notes and links.
Sagredo (Galileo Galilei) "You present these recondite matters with too much
evidence and ease; this great facility makes them less appreciated than they
would be had they been presented in a more abstruse manner." Two New Sciences
Eric Swanson
[cut]
>> In the Arctic Ocean, if the column of water is at nearly freezing to
>> begin with (as it is now), the surface can quickly freeze, once the
>> air temperature drops below freezing. I was just pointing out again
>> the fact that there is almost no possibility of the Arctic Ocean
>> being ice free year round.
>
>It is at freezing now because the (seasonal) ice is melting. Therefore
>sea and air temperature cannot climb above 0C. Once all the ice
>melts, then the sea temperatures can rise above zero and make it
>more difficult for the sea to refreeze.
But the air temperature DOES climb above freezing around the edges where
complete melting occurs today in the Arctic Ocean. With your scenario,
how can new sea-ice form over these areas, which, being further southwards,
are subject to much more solar energy input compared to the water at the
North Pole?
>> Ok, guy, give us a reference for that statement.
>> Ice free at the end of the melt season is not the same as
>> completely free of sea-ice year round.
>
>Chapter 1 of Brooks, C.E.P. (1949). Climate through the Ages: A Study of the
>Climatic Factors and Their Variations (Rev. Ed.). London: Benn.
Are you seriously going to reference the introductory chapter of a 33 year
old book? Does the author provide references to data to support your claim
that the Arctic Ocean was completely free of sea-ice during the Eemian?
DESMODUS
decadal level -during the D/O cycles of the the last cold period temp could
drop by as much as 12 C in less than 10 years meaning perma frost condition
over much of the USA and as far south as the Pyranees in Europe -under these
conditions much of the snow will not melt in winter so that ice sheets 20+m
thick develop in around 100 years -this is why there was no civilisation
before 12K years and probably why it could disapear when these conditions
return ! Desmodus
Alastair McDonald
> In article <bhtspo$gi0$1...@newsg2.svr.pol.co.uk>,
alas...@abmcdonald.leavethisout.freeserve.co.uk says...
> >
> >
> >"Eric Swanson" <swanson@nospam_on.net> wrote in message
> >alas...@abmcdonald.leavethisout.freeserve.co.uk says...
> [cut]
>
> >> In the Arctic Ocean, if the column of water is at nearly freezing to
> >> begin with (as it is now), the surface can quickly freeze, once the
> >> air temperature drops below freezing. I was just pointing out again
> >> the fact that there is almost no possibility of the Arctic Ocean
> >> being ice free year round.
> >
> >It is at freezing now because the (seasonal) ice is melting. Therefore
> >sea and air temperature cannot climb above 0C. Once all the ice
> >melts, then the sea temperatures can rise above zero and make it
> >more difficult for the sea to refreeze.
>
> But the air temperature DOES climb above freezing around the edges where
> complete melting occurs today in the Arctic Ocean. With your scenario,
> how can new sea-ice form over these areas, which, being further southwards,
> are subject to much more solar energy input compared to the water at the
> North Pole?
During mid winter, these areas recieve the same solar energy as at the pole,
precisely zero. Provided there is ice over the pole, the surface and the air
above quickly cools. This more dense air descend forming an anti cyclone
which produces clear skies, and so more cooling. It also produces an outflow
of air as the descending air escapes. This super frozen air then passes over
the edge of the ice which is entering permanent Arctic night, and the ice
spreads out from the pole to the coastline, where as ice it can spread no
further.
> >> Ok, guy, give us a reference for that statement.
> >> Ice free at the end of the melt season is not the same as
> >> completely free of sea-ice year round.
> >
> >Chapter 1 of Brooks, C.E.P. (1949). Climate through the Ages: A Study of
> > the Climatic Factors and Their Variations (Rev. Ed.). London: Benn.
>
> Are you seriously going to reference the introductory chapter of a 33 year
> old book? Does the author provide references to data to support your claim
> that the Arctic Ocean was completely free of sea-ice during the Eemian?
Fifty year old book! But the basic scientific facts don't change, ever.
I have to admit I cannot find a refence to an ice free Arctic. I St J may have
one/two, or none may exist even if the Arctic was ice free during the Eemian.
BTW the reference for Broecker's change of view is
W.S. Broecker "Abrupt climate change: causal constraints provided by the
paleoclimate record" Earth Science Reviews, 51 (2000)
http://www.elsevier.com/pub/9/10/top25.htt?jnl=earth [last on list ie No 24]
Cheers, Alastair.
Alastair McDonald
news:bhu124$7ki$1...@news1.radix.net...
> In article <bhlb3v$k9t$2...@newsg4.svr.pol.co.uk>,
>
> The term is ice pack or sea ice pack. It never forms a sheet (a term
> which implies that it is unbroken, and the ice pack is always broken in
> to ice floes).
I am not thinking of the sea ice as such when I use the term sea ice sheet.
The point is that it is a large area of high albedo surface which is not on
land. Perhaps I should write it sea ice-sheet, as opposed to a normal ice
sheet. There are only one and a half of them on the planet today; the
Arctic Sea, and the Weddell Sea. There are various terms used for
the Arctic ice as a unit, such as ice-cap (Brookes) and ice cover
(Gildor and Tziperman.) I had thought of inventing my own term, but sea
ice sheet seemed to be in common use. For instance see;
http://scilib.ucsd.edu/sio/nsf/gallery/gallery7.html and
http://www.palmod.uni-bremen.de/FB5/kristall/cvogt/PHDAbstr.htm
An ice pack can refer to seasonal ice only, such as that which borders
most of the Antarctic. The point about an ice sheet is that if consists of
both seasonal and permanent ice. When the permanent ice disappears,
so does the seasonal ice.
> Present a quantitative argument demonstrating that and you've
> got a publishable paper. There's no quantitative reason yet to
> believe that water won't freeze in the arctic winter for a good
> long time into the future (speaking minimally: decades).
I have been told that I have to spend a year getting up to speed with
the scientific literature before anyone will listen to me. I had
assumed that what I am describing is well known among sea ice
modellers already, but since there is no agreed name for the
object of my studies, a polar sea ice sheet, then perhaps my ideas
are fairly original, so there is no literature to read :-)
> >For the air tempererature over the open ocean to drop below freezing all
> > 50 to 100 meters of water must cool. For air temperatures over a sea ice
> > sheet to go below zero, only the first centimeter of the ice has to cool.
> > That is why the Arctic will not freeze without permanet ice to seed it.
>
> What is impossible about cooling 50 meters (by the way, it's more like 25
> meters over much of the Arctic) of water by 1 C (water's already about -1 in
> a goodly volume of the Arctic) in a 6 month winter without sun? Please
> be quantitative.
> As a start, the heat capacity of a slab of ocean that is H meters thick is
> rho*c_p*H. rho = density of sea water, about 1025 kg/m^3, and c_p is the
> specific heat, about 4000 J/kg. For 25 meters, this is about 1e8 J/m^2.
> The sun, on global average (and after albedo) supplies about 250 W/m^2.
> Taking that as the magnitude of the winter time heat deficit gives
> (1e8 / 250) seconds, or under 5 days.
But the average depth of the Arctic Ocean is 1000 m, so your estimate would
have to be multiplied by a factor of 40. That gives 200 days, far too long for
an annual freeze.
At present the Arctic is fairly cloud free because the ice allows little
evaporation. With the ice gone the Arctic will become cloudier, and so the
sea surface will not cool as quickly because the radiation is reflected by the
clouds.
> Remember too that Siberia is not far from the Arctic and can be counted
> on to produce cold air for much the same reasons it does now. If the
> Arctic tried to be warm (ice free), I expect (intuitively) that the
> cold air would find its way to the Arctic. (It tends to already).
This is true, and it also applies to the Arctic Canada, Alaska, and perhaps
most importantly, Greenland whose ice sheet is not likely to dissappear
in the near future, I hope.
> You might be right about the loss of an ice pack in the summertime
> causing no ice pack to form in the winter either. But you'll have
> to present something stronger than the fact that you think so to
> persuade anyone. Allusions to 50 meters vs. 1 cm are a start, but
> it's going to take something at least as substantial as my back of
> the envelope above to be convincing.
The problem is that, whereas back of the envelope calculations can
be understood by everyone including me, a full analysis which
included the influence of the adjacent land masses producing not
only cold air which is advected, but also freshwater in the form of
icebergs from glaciers, would have to be based on many assumptions
which even if valid would be subjected to skeptical criticism.
OTOH
> Sagredo (Galileo Galilei) "You present these recondite matters with too much
> evidence and ease; this great facility makes them less appreciated than they
> would be had they been presented in a more abstruse manner." Two New
> Sciences
Cheers, Alastair.
Eric Swanson
>
>"Eric Swanson" <swanson@nospam_on.net> wrote in message
>news:bhulmc$5vr8$1...@news3.infoave.net...
>> In article <bhtspo$gi0$1...@newsg2.svr.pol.co.uk>,
>alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>> >
>> >
>> >"Eric Swanson" <swanson@nospam_on.net> wrote in message
>> >alas...@abmcdonald.leavethisout.freeserve.co.uk says...
>> [cut]
>>
>> >> In the Arctic Ocean, if the column of water is at nearly freezing to
>> >> begin with (as it is now), the surface can quickly freeze, once the
>> >> air temperature drops below freezing. I was just pointing out again
>> >> the fact that there is almost no possibility of the Arctic Ocean
>> >> being ice free year round.
>> >
>> >It is at freezing now because the (seasonal) ice is melting. Therefore
>> >sea and air temperature cannot climb above 0C. Once all the ice
>> >melts, then the sea temperatures can rise above zero and make it
>> >more difficult for the sea to refreeze.
>>
>> But the air temperature DOES climb above freezing around the edges where
>> complete melting occurs today in the Arctic Ocean. With your scenario,
>> how can new sea-ice form over these areas, which, being further southwards,
>> are subject to much more solar energy input compared to the water at the
>> North Pole?
>
>During mid winter, these areas recieve the same solar energy as at the pole,
>precisely zero.
True, however, during the summer melt season, the ocean in these areas receive
much more, being further southwards where the sun rises higher in the sky.
>Provided there is ice over the pole, the surface and the air
>above quickly cools. This more dense air descend forming an anti cyclone
>which produces clear skies, and so more cooling. It also produces an outflow
>of air as the descending air escapes. This super frozen air then passes over
>the edge of the ice which is entering permanent Arctic night, and the ice
>spreads out from the pole to the coastline, where as ice it can spread no
>further.
And how long would it take for new ice to form over the North Pole, should it
become free of sea-ice in any one year? Remember, no input of solar energy,
but a large outflow of infrared thru the night sky 24 hour/day.
>> >> Ok, guy, give us a reference for that statement.
>> >> Ice free at the end of the melt season is not the same as
>> >> completely free of sea-ice year round.
>> >
>> >Chapter 1 of Brooks, C.E.P. (1949). Climate through the Ages: A Study of
>> > the Climatic Factors and Their Variations (Rev. Ed.). London: Benn.
>>
>> Are you seriously going to reference the introductory chapter of a 33 year
>> old book? Does the author provide references to data to support your claim
>> that the Arctic Ocean was completely free of sea-ice during the Eemian?
>
>Fifty year old book! But the basic scientific facts don't change, ever.
Revised in 1970. New scientific findings are built on older ones..
>I have to admit I cannot find a refence to an ice free Arctic. I St J may have
>one/two, or none may exist even if the Arctic was ice free during the Eemian.
I seriously doubt anyone has suggested that the Arctic Ocean was ever completely
free of sea-ice year-round during the Eemian.
>BTW the reference for Broecker's change of view is
>W.S. Broecker "Abrupt climate change: causal constraints provided by the
>paleoclimate record" Earth Science Reviews, 51 (2000)
>http://www.elsevier.com/pub/9/10/top25.htt?jnl=earth [last on list ie No 24]
Thanks. It's another pay for view site ($30), so I'll put it on my list for
my next 40 mile trip to the library......
Eric Swanson
>
>"Robert Grumbine" <bo...@radix.net> wrote
>> In article <bhlb3v$k9t$2...@newsg4.svr.pol.co.uk>,
>
>> >For the air tempererature over the open ocean to drop below freezing all
>> > 50 to 100 meters of water must cool. For air temperatures over a sea ice
>> > sheet to go below zero, only the first centimeter of the ice has to cool.
>> > That is why the Arctic will not freeze without permanet ice to seed it.
>>
>> What is impossible about cooling 50 meters (by the way, it's more like 25
>> meters over much of the Arctic) of water by 1 C (water's already about -1 in
>> a goodly volume of the Arctic) in a 6 month winter without sun? Please
>> be quantitative.
>
>> As a start, the heat capacity of a slab of ocean that is H meters thick is
>> rho*c_p*H. rho = density of sea water, about 1025 kg/m^3, and c_p is the
>> specific heat, about 4000 J/kg. For 25 meters, this is about 1e8 J/m^2.
>> The sun, on global average (and after albedo) supplies about 250 W/m^2.
>> Taking that as the magnitude of the winter time heat deficit gives
>> (1e8 / 250) seconds, or under 5 days.
>
>But the average depth of the Arctic Ocean is 1000 m, so your estimate would
>have to be multiplied by a factor of 40. That gives 200 days, far too long for
>an annual freeze.
The Arctic Ocean below about 150 meters is above freezing. Only the top most
layer must drop below freezing for the formation of sea-ice.
For example, see: EOS (Transactions of the AGU) 84 (30), 281-288, 29 July 2003.
Alastair McDonald
> In article <bil0le$m49$5...@newsg4.svr.pol.co.uk>,
alas...@abmcdonald.leavethisout.freeserve.co.uk says...
> >
> >> > the Climatic Factors and Their Variations (Rev. Ed.). London: Benn.
> >>
> >> Are you seriously going to reference the introductory chapter of a 33
year
> >> old book? Does the author provide references to data to support your
claim
> >> that the Arctic Ocean was completely free of sea-ice during the Eemian?
> >
> >Fifty year old book! But the basic scientific facts don't change, ever.
>
> Revised in 1970. New scientific findings are built on older ones..
I don't think it was revised in 1970, only reprinted. The 1949 edition was a
revised version of the 1922 first edition. My copy is 1949.
> >I have to admit I cannot find a refence to an ice free Arctic. I St J may
have
> >one/two, or none may exist even if the Arctic was ice free during the
Eemian.
>
> I seriously doubt anyone has suggested that the Arctic Ocean was ever
completely
> free of sea-ice year-round during the Eemian.
>
> >BTW the reference for Broecker's change of view is
> >W.S. Broecker "Abrupt climate change: causal constraints provided by the
> >paleoclimate record" Earth Science Reviews, 51 (2000)
> >http://www.elsevier.com/pub/9/10/top25.htt?jnl=earth [last on list ie No
24]
>
> Thanks. It's another pay for view site ($30), so I'll put it on my list for
> my next 40 mile trip to the library......
I got it using my ATHENS password. Don't you have one?
Cheers, Alastair.
Josh Halpern
Eric Swanson wrote:
>In article <bil0le$m49$5...@newsg4.svr.pol.co.uk>,
>
>
>>"Eric Swanson" <swanson@nospam_on.net> wrote
>>
>>
>>During mid winter, these areas recieve the same solar energy as at the pole,
>>precisely zero.
>>
Not quite. There is the inflow of energy from the solar wind (aka
northern lights)
josh halpern
Alastair McDonald
"Josh Halpern" <j.ha...@incoming.verizon.net> wrote in message
news:3F4EEA44...@incoming.verizon.net...
And how many Watts per square metre does that provide at 70 degs. N
say compared to the pole?
Cheers, Alastair.
Phil Hays
<snip>
> As a start, the heat capacity of a slab of ocean that is H meters thick is
> rho*c_p*H. rho = density of sea water, about 1025 kg/m^3, and c_p is the
> specific heat, about 4000 J/kg. For 25 meters, this is about 1e8 J/m^2.
> The sun, on global average (and after albedo) supplies about 250 W/m^2.
> Taking that as the magnitude of the winter time heat deficit gives
> (1e8 / 250) seconds, or under 5 days.
Heat loss wouldn't be that large. Even in the current Arctic, I don't
think that it is that large. See:
http://www.arctic.noaa.gov/gallery_np_weatherdata.html
Note that the LW radiation balance at the surface would be roughly:
LWnet = LWsurface - LWobserved
= k*T^4 - (200 to 300 W/m*m)
= 5.67*10^-8*(273^4) - (200 to 300 W/m*m)
= 114 W/m*m to 14 W/m*m
Physics of Climate gives 120 W/m*m net annual loss at top of atmosphere
(Figure 6.11a), and 140 W/m*m during winter. Note that this heat is
mostly transported by the ocean from the tropics.
> Remember too that Siberia is not far from the Arctic and can be counted
> on to produce cold air for much the same reasons it does now. If the
> Arctic tried to be warm (ice free), I expect (intuitively) that the
> cold air would find its way to the Arctic. (It tends to already).
Also Greenland would be a source of cold air for at least decades.
> You might be right about the loss of an ice pack in the summertime
> causing no ice pack to form in the winter either. But you'll have
> to present something stronger than the fact that you think so to
> persuade anyone. Allusions to 50 meters vs. 1 cm are a start, but
> it's going to take something at least as substantial as my back of
> the envelope above to be convincing.
I suspect he is correct. The main reason is that fossil trees from
above the (then) Arctic circle from warmer periods of geologic history
show a growth pattern implying above freezing all year round. If there
was sea ice, then the Spring season would start out with some below
freezing weather.
However, showing this in a substantial way isn't easy. How would ocean
heat transport change in a warmer world? What would cloud variations be
like?
Another issue is that climate models don't show the Arctic above
freezing without the tropics being hotter than reasonable.
--
Phil Hays
Titan Point
> In article <Xns93CCD8C9B16E2T...@212.83.64.229>, Thoma...@chello.removethis.se says...
>>
>>James Acker <jac...@linux1.gl.umbc.edu> wrote in news:bgm93e$q2c$1
>>@news.umbc.edu:
>>
>>> Just wanted to note: being a member of the American Geophysical
>>> Union (AGU) gets you a subscription to Physics Today, and at least
>>> 80% of the content is beyond my comprehension (usually out of my
>>> field). But the August issue has an article called "The Discovery
>>> of Rapid Climate Change" that's quite interesting.
>>>
>>> Online here (longer and with fully-linked references):
>>> http://www.aip.org/history/climate/rapid.htm
>>>
>>>
>>> Apparently the author of the piece, Spencer Weart, has
>>> a book out entitled "The Discovery of Global Warming" (Harvard
>>> University Press).
>>
>>You can find it all at the same site:
>>http://www.aip.org/history/climate/
>>
>>It's a very useful reference.
>
> The history of the AGW debate up to the year 1980 is even more interesting:
>
> http://www.aip.org/history/climate/Public.htm#M_63_
> and continuing after 1980:
> http://www.aip.org/history/climate/public2.htm
>
> William Connolley should be envious, as there are many references to the
> so-called "Global Cooling Scare" and a discussion about it's development.
Yes, but Bill has the "but no scientific consensus" exit strategy. Come to
think of it, there's no "human induced global warming" scientific
consensus now...but lots and lots of hot air.
Titan Point
>
> I haven't sent the author a link to my page (feel free to do so if you like).
> As Thomas Palm (in full!) says, they are different. I did feel that the
> pages somewhat skate over the cooling stuff, but then I'm biased.
>
> -W.
Yes. You are.
Ian St. John
"Titan Point" <titanpoi...@myrealbox.com> wrote in message
news:pan.2003.08.30...@myrealbox.com...
Not an exit strategy. As the lack of scientific literature beyond the
occasional speculation and projection indicates there was little movement in
the sciences on this issue before it was resolved by the EPA clean air and
other regulations.
> Come to
> think of it, there's no "human induced global warming" scientific
> consensus now...
It is hardly a thought, just a lie. The solid consensus including a major
summarization involving 2500 scientists and tens of thousands of papers is
not to be ignored as you do. Expecially when it has been backed by ever
major scientific academy as representing the scientific consensus.
> but lots and lots of hot air.
You have no end of that, all right.
Eric Swanson
No consensus? What do you think this means?
http://www.agu.org/sci_soc/policy/climate_change_position.html
--------------------
Climate Change and Greenhouse Gases
Adopted by Council December, 1998. Reaffirmed December, 2002
Atmospheric concentrations of carbon dioxide and other greenhouse gases have
substantially increased as a consequence of fossil fuel combustion and other
human activities. These elevated concentrations of greenhouse gases are
predicted to persist in the atmosphere for times ranging to thousands of years.
Increasing concentrations of carbon dioxide and other greenhouse gases affect
the Earth-atmosphere energy balance, enhancing the natural greenhouse effect
and thereby exerting a warming influence at the Earth's surface.
............
The world may already be committed to some degree of human-caused climate
change, and further buildup of greenhouse gas concentrations maybe expected to
cause further change. Some of these changes may be beneficial and others
damaging for different parts of the world. However, the rapidity and uneven
geographic distribution of these changes could be very disruptive. AGU
recommends the development and evaluation of strategies such as emissions
reduction, carbon sequestration, and adaptation to the impacts of climate
change. AGU believes that the present level of scientific uncertainty does
not justify inaction in the mitigation of human-induced climate change
and/or the adaptation to it.
---------------
TP Guy, it's you who are full of hot gas.
Lloyd Parker
OK, you come back and lie in your second post. You really are addicted to it,
aren't you?
James Acker
: Come to think of it, there's no "human induced global warming" scientific
: consensus now...but lots and lots of hot air.
consensus: 1 a : general agreement : UNANIMITY <the consensus of
their opinion, based on reports... from the border -- John Hersey> b : the
judgment arrived at by most of those concerned <the consensus was to go
ahead>
2 : group solidarity in sentiment and belief
If consensus is considered equivalent to unanimity, you would be
correct. If consensus is considered equivalent to "the judgment arrived
at by most of those concerned", you would be wrong.
Jim Acker
*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
Jim Acker
jac...@gl.umbc.edu
"Since we are assured that an all-wise Creator has observed the
most exact proportions, of number, weight, and measure, in the
make of all things, the most likely way therefore, to get any
insight into the nature of those parts of the creation, which
come within our observation, must in all reason be to number,
weigh, and measure." - Stephen Hales