Take 2 - Future weather projections
 

H. E. Taylor wrote:
Greetings,
Well this has been interesting. In spite of my request
to not worry about the validity of the assumptions, that
is precisely what 95% of responders did.
sigh

If you are writing science fantasy anyway,
why worry if any of the responses are valid?

Think of it this way.
There is this great big weather machine.
Do we undertand how it works?
What will it do if we set different initial conditions?
[Aside: this is sometimes called a 'what-if' scenario.]

Assume X, Y & Z. What is the resulting weather?
[What are the critical factors?
See IPCC: 6.13 Global Mean Radiative Forcings
http://www.grida.no/climate/ipcc_tar/wg1/251.htm]

*** If you don't like the assumptions,
treat it as a thought exercise.***

Assume the average global temperature rises 8C by 2500.
Assume the Arctic is ice free in the summer.
[Note that a lot of relevant IPCC factors are not specified.]

1) What would be the effect on the circumpolar vortex?
2) What would be the effect on the jet stream?
3) What will be the effect of an ice free Arctic on North
American, [& northern hemispheric] weather patterns?
4) Will the prevailing winds be shifted or re-oriented?

It is the mid-North American weather patterns in which I am most
interested. The weather here is roughly a result of the
interaction of Arctic circulation and Pacific fronts which
usually come up from the south west. How will that change?
Further desertification? New wind patterns?

curious
-het

Take 2 - Future weather projections
 

"H. E. Taylor" wrote in message
...
Greetings,
Well this has been interesting. In spite of my request
to not worry about the validity of the assumptions, that
is precisely what 95% of responders did.
sigh

Since there were only about 5 responder, I must assume
that I was the one who was responsible for the odd 15%!

One reason you are not getting your question answered
is because no one knows the answer, not only on these
newsgroups but also amongst the great scientific
establishment. The evidence would come from geologists,
but as most of them are employed by the oil industry, they
are not very sympthetic to suggestions of AGW. They
are also more concerned about things happening over
much longer timescales than 50 years.

Moreover the evidence of past climates, especially on
a local scale, is not readily available even to geologist.
In the case of North America, much of it was under a
shallow sea until recently in a geological sense. But on
the other side of the pond we do have some
new data. See;
http://news.bbc.co.uk/1/hi/sci/tech/3080854.stm

HTH,

Cheers, Alastair.

Take 2 - Future weather projections
 

Greetings,
Well this has been interesting. In spite of my request
to not worry about the validity of the assumptions, that
is precisely what 95% of responders did.
sigh
Think of it this way.
There is this great big weather machine.
Do we undertand how it works?
What will it do if we set different initial conditions?
[Aside: this is sometimes called a 'what-if' scenario.]

Assume X, Y & Z. What is the resulting weather?
[What are the critical factors?
See IPCC: 6.13 Global Mean Radiative Forcings
http://www.grida.no/climate/ipcc_tar/wg1/251.htm]

*** If you don't like the assumptions,
treat it as a thought exercise.***

Assume the average global temperature rises 8C by 2500.
Assume the Arctic is ice free in the summer.
[Note that a lot of relevant IPCC factors are not specified.]

1) What would be the effect on the circumpolar vortex?
2) What would be the effect on the jet stream?
3) What will be the effect of an ice free Arctic on North
American, [& northern hemispheric] weather patterns?
4) Will the prevailing winds be shifted or re-oriented?

It is the mid-North American weather patterns in which I am most
interested. The weather here is roughly a result of the
interaction of Arctic circulation and Pacific fronts which
usually come up from the south west. How will that change?
Further desertification? New wind patterns?

curious
-het






--
"Humanity is performing a 'great geophysical experiment', not in a laboratory,
not in a computer, but on our own planet." -R. Revelle & H. E. Suess(1957)

Global Warming: http://www.autobahn.mb.ca/~het/globalwarming.html
H.E. Taylor http://www.autobahn.mb.ca/~het/

OT: Take 2 - Future weather projections
 

In article ,
Steve McGee wrote:
[...]
If you are writing science fantasy anyway,
why worry if any of the responses are valid?

Welcome to the endless discussion regarding the difference
between science fiction and fantasy. Actually it's more
like you are welcome to it. I don't care about fantasy.

[...]

live well
-het



--
"Human history becomes more and more a race between education and
catastrophe." -H.G. Wells

How's yer crap detector? http://www.autobahn.mb.ca/~het/detector.html
H.E. Taylor http://www.autobahn.mb.ca/~het/

Take 2 - Future weather projections
 

In article ,
k Alastair McDonald wrote:

[...]
One reason you are not getting your question answered
is because no one knows the answer,


Yes but...
I was hoping for a good theory. ;-))

[...]
Moreover the evidence of past climates, especially on
a local scale, is not readily available even to geologist.


Yes but...
It is arguable that humans are triggering a rate of change
not seen in the paleoclimate record, which dumps us back
on first principles.

[...]

live well
-het



--
"It is difficult to say what is impossible, for the dream of yesterday
is the hope of today and reality of tomorrow." - Robert Goddard

Home of the PV FAQ: http://www.autobahn.mb.ca/~het/energy/pv_faq.html
H.E. Taylor http://www.autobahn.mb.ca/~het/

Take 2 - Future weather projections
 

"H. E. Taylor" wrote in message
...
In article ,
k Alastair McDonald wrote:

I was hoping for a good theory. ;-))

It is arguable that humans are triggering a rate of change
not seen in the paleoclimate record, ...

Well not really! I now seems as though the Late Palaeocene
Thermal Maximum (LPTM) was caused by a large methane
hydrate release which would have caused an even more
abrupt climate change than is being caused by humans. Use
google.com to find out more about the LPTM.

Of course, if I am right, then we will get a 5C increase by
2050 but it will happen in a period of a few years, not
spread over the whole 50. It will happen when the Arctic ice
melts, reducing global albedo. The increase in temperature
will cause runaway warming from more water vapour and the
greenhouse effect from it . This runaway warming will end
when the climate has changed such that increased clouds
cover compensates for the loss of ice in the albedo stakes.

Now for the speculation: clouds are not linearly dependent on
humidity. So the increase in clouds may involve a new
climatic regime. The polar vortex will no longer exist, because
there will be no cooling to cause a descending air stream.
Since the areas of rising and falling air must be equal in the
atmosphere, it is dificult to see what will happen, but we
may see rising air in the Arctic with descending air in only the
sub-tropics which will have moved poleward. So you have a
tropical region, wider than at present and wetter, and a
permanent source of hurricanes. The deserts would move
north crossing the Mediterranean and into the south of the
USA. Mediterranen climates would move into Britain,
the Great Lakes, Seattle and Vancouver. The Arctic would
return to the state when it was coal forming swamps, with
mild winters caused by permanent cloud cover. Of course
this is a non-seasonal description. The Arctic especially
will still be seasonal. During the summer they may be
an anticyclone there with high tempertures no longer limited
by melting ice on the surface.

The warmth would rapidly melt the Greenland ice sheet,
causing sea level rise, flooding coastal plains. This would
lead to a greater water surface and more water vapour in
the atmosphere, so more warming. The rise in sea level
would also break off the Antarctic ice shelves, which would
float north, melt, and reduce plantary albedo. This would
begin a postive feedback process which would melt the
Antarctic ice sheets as well. This would not all happen by
2050, though perhaps the removal of the ice shelves could
have happened by then.

I suppose the bad news is that it is probably too late to stop
all this happening away :-(

Cheers, Alastair.

Take 2 - Future weather projections
 

In article ,
H. E. Taylor wrote:
Greetings,
Well this has been interesting. In spite of my request
to not worry about the validity of the assumptions, that
is precisely what 95% of responders did.
sigh

rec.arts.sf.science is probably a better group for the sort of
consideration you'd like.

*** If you don't like the assumptions,
treat it as a thought exercise.***

Assume the average global temperature rises 8C by 2500.
Assume the Arctic is ice free in the summer.
[Note that a lot of relevant IPCC factors are not specified.]

Fair chance that for that amount of warming, and that time scale,
that the Arctic would be ice free year-round.

1) What would be the effect on the circumpolar vortex?

Well, in the NH, we don't have a solid circumpolar vortex in the
first place. The reason for that is the land-sea distribution,
aided by the presence of an ice sheet in Greenland. For that
magnitude of warming, and the 500 years, it's plausible that
Greenland will have melted away by then, permitting a more
vortex-like structure.

Not specified, and important, is whether the warming is uniform
with respect to latitude or not. Most expectations, based in part
on geological history, include increased warming towards the poles.
Given that, then a weaker vortex would be expected.

Net is to trade between a stronger vortex from melting off
Greenland, and a weaker vortex from the smaller latitudinal
temperature gradient. Pick whichever makes the story better :-)

2) What would be the effect on the jet stream?

If the equator-pole temperature gradient drops, expect a
weaker jet stream. Also, to judge by weather in our warmer
recent years, expect the jet stream to move some degrees
further poleward.

3) What will be the effect of an ice free Arctic on North
American, [& northern hemispheric] weather patterns?

Expect a lot more precip over high latitude land. If the
ocean goes ice free in the winter as well, expect much, much
more snow on land in high northern latitudes. Keep in mind
that this was the basis of a theory for ice age initiation from
the 1950s to early 1970s that was abandoned for reasons I still
haven't been able to track down.

Given ice free arctic and extensive snow cover in high latitude
land, expect strong near-polar storms due to the thermal contrast.

4) Will the prevailing winds be shifted or re-oriented?

Now that one's easy: Sure. The question of 'in which ways' is
not so easy.

As a start, figure we'll still have a '3 cell' circulation.
Though it's a misnomer to refer to 3, it's a handy simplification.
In other words, the tropical circulation will still be rising at
the equator and descending in the subtropics. The exact location
of descent will probably shift, and aesthetically I expect it to
weaken and move towards the equator. But I don't have a good
dynamical reason at hand, so feel free to reverse those signs.

The mid-latitude 'cell' is really the average of storm systems.
We intuitively expect that a reduced equator to pole temperature
gradient will reduce size and strength of storms, but that hasn't
been supported yet by observations (afaik).

The storm 'track' should shift along with the jet stream, to the
north. That can move the winter storm lines out of the central US
and up to southern Canada. Chicago, instead of its 'traditional'
meter or so of snow, and average January high of 19F, could wind
up with rain instead of snow, and a near freezing January high.
(As happened this past winter).


Anyhow, as long as you stay away from doing anything dreadful,
as happened in 'Fallen Angels' (Niven, Pournelle, Barnes), you're
fairly safe. Do be sure, of course, that you don't try to attribute
a reason for the 8 C shift. The rest can follow from that, but
you can have a lot of trouble if you put up any particular reason.

--
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

Take 2 - Future weather projections
 

On Sun, 07 Sep 2003 14:03:01 -0600, Steve McGee
wrote:

H. E. Taylor wrote:
Greetings,
Well this has been interesting. In spite of my request
to not worry about the validity of the assumptions, that
is precisely what 95% of responders did.
sigh

If you are writing science fantasy anyway,
why worry if any of the responses are valid?

Because he asked a simple question. If you don't wish to
answer it, stay out of the thread. Very simple. Even the greatest
dullard around should be able to follow along. What's your excuse?

Take 2 - Future weather projections
 

"Robert Grumbine" wrote in message
...
In article ,
H. E. Taylor wrote:
Snip

3) What will be the effect of an ice free Arctic on North
American, [& northern hemispheric] weather patterns?

Expect a lot more precip over high latitude land. If the
ocean goes ice free in the winter as well, expect much, much
more snow on land in high northern latitudes. Keep in mind
that this was the basis of a theory for ice age initiation from
the 1950s to early 1970s that was abandoned for reasons I still
haven't been able to track down.

I would expect that it could only be due to sediment cores not showing an
ice free arctic in association with the start of the ice ages. The increase
in sedimentation rate from the biological activity of an ice free arctic
would be clear and distinct.

http://www.pibburns.com/smmia2.htm#source5
"Since the 1960's several hundred sediment cores have been retrieved from
the central Arctic. In the world's deep oceans, sediment rich in biological
remains normally accumulates at rates varying from 1.5 to 3 centimeters per
thousand years. 27 In contrast to this, the sedimentation rate in the Arctic
cores has been only about 1.5 to 2 millimeters per thousand years over the
last 700,000 years or so, with the average at the low end of this range for
the last 70,000 or 80,000 years. It is very poor in biological material,
consisting largely of ice-rafted gravel. Everybody who has studied these
cores has agreed that the Arctic has remained ice-covered for at least the
last 70 or 80 thousand years. If the sea had been open for several thousand
years as Ginenthal claims, and therefore capable of supporting large-scale
photosynthesis, it would be quite obvious from a tenfold increase in
sedimentation and a dramatic change incomposition in the cores. Hunkins and
Kutschale note: "

OT: Take 2 - Future weather projections
 

In article ,
Robert Grumbine wrote:

[much stuff]


Just wanted to thank you for the thoughtful replies.

regards
-het


PS.
You too Alistair.


--
"If they can get you asking the wrong questions,
they don't have to worry about answers." -Thomas Pynchon

Hutton Inquiry: http://www.autobahn.mb.ca/~het/terror_war/hutton.html
H.E. Taylor http://www.autobahn.mb.ca/~het/