On Sun, 11 Sep 2011 20:30:47 +0100, Adam Lea wrote:

After the very destructive 2004 & 2005 hurricane seasons there was some
suggestion that a warming climate was increasing the intensity of
tropical cyclones. The general consensus now is that in a warmer
climate, tropical cyclone numbers globally will decrease

The "suggestion" that a warming climate would increase the number and
intensity of cyclones predates 2004 by a few decades. With increasing sea
temperatures I'd expect this to happen and for them to spread their area
of influence.

Is the counter-argument something to do with the upper troposphere being
forecast to warm more than lower down and so reducing instability?
Against that, the stratosphere is cooling as expected and so I'd expect
the depth of the troposphere to be increasing and hence, depth of
instability.

The last few years, hurricanes seem to have been hampered by shear more
than I've seen before. Has that got anything to do with the forecast
reductions?



--
Graham Davis, Bracknell
Whilst it's true that money can't buy you happiness, at least you can
be miserable in comfort.
Newsreader for Windows, Mac, Unix family: http://pan.rebelbase.com/

In article ,
says...
Is the counter-argument something to do with the upper troposphere being
forecast to warm more than lower down and so reducing instability?


I have heard it said, by those more knowledgeable than me, that the
reduction in the polar-equatorial temperature gradient (due to the poles
warming faster) would make tropical storms less likely, by making it
more difficult for "disturbed" ares of weather to organise.



--
Alan LeHun

On Sep 11, 7:37*pm, "Col" wrote:
Lawrence13 wrote:
On Sep 11, 5:18 pm, "Col" wrote:
Lawrence13 wrote:
On Sep 11, 4:30 pm, "Col" wrote:

Never mind the jokes Lawrence, I asked a serious question.
You talk of 'cooling ahead'. When will this said cooling lead
to an arctic sea extent comparable to the 1972-2008 average?
--
Col

Bolton, Lancashire
160m asl- Hide quoted text -

- Show quoted text -

I could turn that around Col and say when will these said rising sea
levels threaten our coastlines. When will the said increase in super
sized hurricanes start. Or when will the said disapearance of
snowfall begin. When all is said and done there's nothing shaking
but the leaves in the tree. I'm still waiting for the last said
three BBQ summers and they were predicted by tn experts the Met
Office, and golly gosh if anyone knows about AGW then they do.

You've answered a question with a question, Lawrence.

I ask again:
When will this said cooling lead to an arctic sea extent comparable
to the 1972-2008 average?
--
Col

Bolton, Lancashire
160m asl- Hide quoted text -

- Show quoted text -

The coming decade. Now answer mine.

Rising sea levels - nobody ever said we would be innundated
during the first couple of decades of the 21st century. It was
always a 50-100 year thing.

Super-hurricanes- *don't know about this one, you will have
to expand further.

Disappeareance of snowfall - Do you mean in the UK or in
the world in general? Do not allow a couple of cold & snowy
Decembers to delude you into thinking that the world climate
has changed.

BBQ Summers - I only ever remember one barbeque summer,
not three. You can take a swipe at the Met Office if you want to
but the scientific reasoning behind predicting the weather on a daily,
weekly or even seasonal basis is far removed from predicting the
general trends of AGW which take place over *decades*.
--
Col

Bolton, Lancashire
160m asl- Hide quoted text -

- Show quoted text -

"Rising sea levels - nobody ever said we would be innundated
during the first couple of decades of the 21st century. It was
always a 50-100 year thing."

Well Col let's look at sea level rise from the IPCC in 1990 in their
first assessment under impacts in which they say

"These scenarios pre-date, but are in line with, the assessment of
Working Group I which, for Scenario A (Business-as-Usual) has
estimated the magnitude of sea-level rise at about 20 cm by 2030"

In fact the sea level rise hasn't even been half that figure so far
with levels actually now falling that means for the IPCC prediction to
come true we need to see a 15 cm rise in the next 19 years so it had
better get it's skates on
http://www.ipcc.ch/ipccreports/1992%...r_overview.pdf

and

http://www.jpl.nasa.gov/news/news.cfm?release=2011-262


I'll continue tomorrow.

"Lawrence13" wrote:

....
Still not as warm as the last
interglacial - cooling ahead.

Not likely. Even if we reduced our emissions to zero (which
realistically
isn't going to happen, short of 7 billion people succumbing to a fatal
disease), global temperature would stabilise, but not fall.

http://www.realclimate.org/index.php...limate-change-...

If the cooling isn't imminent then that is fantastic news, it would
mean that humans utilised all that energy to bring to the cusp of
fantastic things that weren't even dreamt a couple of hundred years
ago and in doing so we get a bonus of a far more benign climate, far
more plant food in the atmosphere and thus better food production.
Looks like a win/ win to me. I still feel though that global cooling
is our future which would be a disaster. Let's keep our fingers
crossed that humans have slightly warmed the planet, because if other
climate forcing's far outweigh that of humans 100 PPM of co2 then we
are eventually in big, big trouble. If however our paltry 100ppm has
staved of global cooling then who said there's no such thing as a free
lunch. How good is that?

Does 8°C hotter qualify as 'far more benign' than 5°C colder? I'm not so
sure. We could be heading that way in a few decades. As for 'paltry', in
just 250 years our greenhouse gas forcing has reached 2.6W/m² - it took *125
million years* for solar irradiance to increase by an equal amount... and a
globally averaged forcing from Milankovitch cycles of less than 0.25W/m² was
enough to make the difference between the depths of an ice age and the
relative warmth of an interglacial... so I would say our greenhouse gas
forcing is pretty significant.

On 11/09/11 22:11, Graham P Davis wrote:
On Sun, 11 Sep 2011 20:30:47 +0100, Adam Lea wrote:

After the very destructive 2004& 2005 hurricane seasons there was some
suggestion that a warming climate was increasing the intensity of
tropical cyclones. The general consensus now is that in a warmer
climate, tropical cyclone numbers globally will decrease

The "suggestion" that a warming climate would increase the number and
intensity of cyclones predates 2004 by a few decades. With increasing sea
temperatures I'd expect this to happen and for them to spread their area
of influence.

Is the counter-argument something to do with the upper troposphere being
forecast to warm more than lower down and so reducing instability?
Against that, the stratosphere is cooling as expected and so I'd expect
the depth of the troposphere to be increasing and hence, depth of
instability.


One counter-argument is that it is not just the surface that would warm,
but the whole depth of the troposphere thus the vertical instability
would remain unchanged and the sea surface temperature threshold for
tropical storm formation would increase.

Another counter-argument is a (fairly) recent paper suggesting (via
climate model studies) that vertical wind shear will increase over the
Atlantic in a warming climate (something to do with changes in the
Walker circulation, I believe).

http://www.eurekalert.org/pub_releas...-aci041607.php

The last few years, hurricanes seem to have been hampered by shear more
than I've seen before. Has that got anything to do with the forecast
reductions?


Well last year was one of the most active on record, it was just no
hurricanes hit the U.S. 2009 was suppressed by a combination of Saharan
air outbreaks and an El Nino. 2008 was active and destructive. 2007 was
an oddball, much less active than it should have been given La Nina
conditions (I think that was due to wind shear). This year, it seems to
be reduced vertical instability that is hampering developing storms.
There are plenty of storms forming, just they are struggling to
intensify. This was similar to the case in early-mid August 2010 where
there was a break in TC activity until the lid came off in the third
week (that was due to reduced vertical instability as well).

We have just gone back into a La Nina so it may be we get some enhanced
late season activity this year (and a possibility of going into the
Greek alphabet again).

I have to say this years hurricane season is one of the most ridiculous
I have seen - 14 named storms but only two hurricanes so far. It also
looks like, since Irene, the U.S. hurricane deflector shield is back in
place with Atlantic storms recurving and TC Nate being driven into Mexico.

Lawrence13 wrote:
On Sep 11, 7:37 pm, "Col" wrote:


"Rising sea levels - nobody ever said we would be innundated
during the first couple of decades of the 21st century. It was
always a 50-100 year thing."

Well Col let's look at sea level rise from the IPCC in 1990 in their
first assessment under impacts in which they say

"These scenarios pre-date, but are in line with, the assessment of
Working Group I which, for Scenario A (Business-as-Usual) has
estimated the magnitude of sea-level rise at about 20 cm by 2030"

In fact the sea level rise hasn't even been half that figure so far
with levels actually now falling that means for the IPCC prediction to
come true we need to see a 15 cm rise in the next 19 years so it had
better get it's skates on
http://www.ipcc.ch/ipccreports/1992%...r_overview.pdf

and

http://www.jpl.nasa.gov/news/news.cfm?release=2011-262

If you actually read that article it says that the decline, and we're still
only talking half a centimetre in a 5cm rise since 1993, is a mere
temporary affair. It has been caused by La Nina giving extra rainfall
in Australia and South America. The general trend is still strongly upwards.
--
Col

Bolton, Lancashire
160m asl

In article ,
Alan LeHun writes:
In article ,
says...
Is the counter-argument something to do with the upper troposphere being
forecast to warm more than lower down and so reducing instability?


I have heard it said, by those more knowledgeable than me, that the
reduction in the polar-equatorial temperature gradient (due to the poles
warming faster) would make tropical storms less likely, by making it
more difficult for "disturbed" ares of weather to organise.


I can see how a reduced polar-equatorial temperature gradient might
reduce the number or intensity of mid-latitude depressions, but I can't
see how it could have an effect on hurricanes. But then my knowledge of
atmospheric dynamics isn't very good.
--
John Hall
"Men occasionally stumble over the truth, but most of them pick
themselves up and hurry off as if nothing ever happened."
Winston S Churchill (1874-1965)

On Sep 11, 7:31*pm, Dawlish wrote:
On Sep 11, 6:41*pm, Lawrence13 wrote:





On Sep 11, 5:18*pm, "Col" wrote:

Lawrence13 wrote:
On Sep 11, 4:30 pm, "Col" wrote:

Never mind the jokes Lawrence, I asked a serious question.
You talk of 'cooling ahead'. When will this said cooling lead
to an arctic sea extent comparable to the 1972-2008 average?
--
Col

Bolton, Lancashire
160m asl- Hide quoted text -

- Show quoted text -

I could turn that around Col and say when will these said rising *sea
levels threaten our coastlines. When will the said increase in super
sized hurricanes start. Or when will the said disapearance of snowfall
begin. When all is said and done there's nothing shaking but the
leaves in the tree. *I'm still waiting for the last said *three BBQ
summers *and they were predicted by tn experts the Met Office, and
golly gosh if anyone knows about AGW then they do.

You've answered a question with a question, Lawrence.

I ask again:
When will this said cooling lead to an arctic sea extent comparable
to the 1972-2008 average?
--
Col

Bolton, Lancashire
160m asl- Hide quoted text -

- Show quoted text -

The coming decade. Now answer mine.- Hide quoted text -

- Show quoted text -

Why on earth would you think that? And why doesn't anyone working in
the cryosphere appear to agree with you? Doesn't it concern you that
none do?- Hide quoted text -

- Show quoted text -

Another avoidance. You've been asked direct questions. Answer them.
You appear quick to demand that of others. Why do you expect Arctic
sea ice to decline in the next decade? That seems bizarre and goes
against every scientist working in the cryosphere area.

In article , nospam_nov03
@jhall.co.uk says...

I can see how a reduced polar-equatorial temperature gradient might
reduce the number or intensity of mid-latitude depressions, but I can't
see how it could have an effect on hurricanes. But then my knowledge of
atmospheric dynamics isn't very good.


Better than mine. I am at the very bottom of the pile for anything on-
topic in this particular ng.

I always understood the mechanism as being a reduction in the capability
of systems (tropical waves) to organise themselves, rather than any
effect on a system once it had become tropical.



--
Alan LeHun

On Sep 12, 5:50*pm, Dawlish wrote:
On Sep 11, 7:31*pm, Dawlish wrote:





On Sep 11, 6:41*pm, Lawrence13 wrote:

On Sep 11, 5:18*pm, "Col" wrote:

Lawrence13 wrote:
On Sep 11, 4:30 pm, "Col" wrote:

Never mind the jokes Lawrence, I asked a serious question.
You talk of 'cooling ahead'. When will this said cooling lead
to an arctic sea extent comparable to the 1972-2008 average?
--
Col

Bolton, Lancashire
160m asl- Hide quoted text -

- Show quoted text -

I could turn that around Col and say when will these said rising *sea
levels threaten our coastlines. When will the said increase in super
sized hurricanes start. Or when will the said disapearance of snowfall
begin. When all is said and done there's nothing shaking but the
leaves in the tree. *I'm still waiting for the last said *three BBQ
summers *and they were predicted by tn experts the Met Office, and
golly gosh if anyone knows about AGW then they do.

You've answered a question with a question, Lawrence.

I ask again:
When will this said cooling lead to an arctic sea extent comparable
to the 1972-2008 average?
--
Col

Bolton, Lancashire
160m asl- Hide quoted text -

- Show quoted text -

The coming decade. Now answer mine.- Hide quoted text -

- Show quoted text -

Why on earth would you think that? And why doesn't anyone working in
the cryosphere appear to agree with you? Doesn't it concern you that
none do?- Hide quoted text -

- Show quoted text -

Another avoidance. You've been asked direct questions. Answer them.
You appear quick to demand that of others. Why do you expect Arctic
sea ice to decline in the next decade? That seems bizarre and goes
against every scientist working in the cryosphere area.- Hide quoted text -

- Show quoted text -

You know back in the eighties when I was active on the left-the WRP in
fact. I remember saying to my internationalist comrades that now the
Trade Union movement has been curtailed by Thatcher our anti
capitalist stance should now be for the environment and particularly
AGW which I was gung-ho for in those days. For only socialism and
world revolution could/ can save the planet from global warming
disaster -yeah right the old soviet union and china were great
examples to follow.

So you see my little Dawlish Ying to my yang. I've been down that
route and in fact was a bleedin' pioneer of that shining green garden
path. That's why my views are now firmly , yes there has been warming,
and yes some may be due to fossil fuels being used to drag humans from
their wretched miserable existence only up until a hundred odd years
ago. However 90 odd % is political and from the IPCC what would you
expect.

As Richard Lindzen said something along the lines off:
You would have been hard pressed to find a couple of hundred climate
scientist thirty years ago now there are tens of thousands. Just doing
a study on sea temperature change and turtle droppings qualifies you
to be a climate scientist now
Whilst I'm at it my figures quoted from the IPCC first report in 1990
for sea level rise was correct and yet no one has the decency to
recognise that truth? Hey don't let the facts spoil a good ideology