> As for Bangledesh and the like -- the fear is not of a
> multi-decade rise in sea level, but of a typhoon or hurricane
> surge that is higher than those in the past. The increase in
> height need not be much, just enough to cause survivors to leave
> the coast rather than stay.
That's true...but the evidence supporting global warming causing
stronger hurricanes is far weaker than that supporting global
warming. It's mixed at the moment ...
As far as I know, rivals have not much studied hurricanes crossing
warm core eddies. Studies have been on sea surface temperatures
instead. Unfortunately, my knowledge of hurricanes suggests that they
retain or become more powerful when they cross water that stays warm a
long ways down rather than water that is warm on the surface but is
cold further down. Hurricanes really churn the ocean. And they need
lots of energy.
So I am more inclined to think that warm core ocean eddies provide a
better predictor than simple sea surface temperatures. Also, I am
told that modern satellites can provide information on rather small
ocean height differences. In combination with warm, satellite-sensed
sea surface temperatures, an ocean height increase tells you the
location of a warm core eddie. Put another way, with a prediction of
a hurricane's path, which has got better in the past decade, and a
knowledge of warm core ocean eddies, a meteorologist can predict a
hurricane's intensity better than in the past.
> Past observations have shown that when hurricanes pass over
> warm core ocean eddies and are located in atmospheric
> conditions favorable for strengthening, they will often
> strengthen ...
Yes...but heat differential and wind sheer are also critical
factors....and models indicate that heat differential should stay
fairly constant and that shear will rise with
temperatures....which inhibits the formation of large hurricanes.
I agree that the heat differential should stay fairly constant.
However, it is not clear to me what the net effect of wind shear will
be on a decade by decade basis. Will it provide enough counter
feedback? (Obviously, the amount of wind shear will go up and down on
an annual basis. For the Atlantic, it will depend on the Pacific El
Nino and other factors. Also, the development of hurricanes appears
to depend on conditions in the Sahara.)
... the odds on things staying close to the same are very slim in
all models. After changes in rainfall, changes in vegetation
growth patterns due to changes in temperatures will probably be
the greatest impact.
I agree. Or maybe rain, which depends on temperature, is a more
proximate cause of impact.
From what we've seen and modelled, the tropics will be the least
affected ...
Weirdly enough, that may not be the case for humans. In an article in
Science, Vol. 316, 13 April 2007, on the report issued following an
agreement among bureaucrats from more than 100 countries as well as
climate specialists, the author says that a small warming in the
tropics is more than plants can handle. (Specifically, the text is
about yields in a harvest. In the tropics, yeilds go down with a
relatively small temperature rise.)
In other words, without further genetic engineering, without another
`green revolution', more people will have trouble. If there is only a
little hunger, and it is expected to continue, people may migrate.
(Too much starvation and people will not be able to migrate.)
As you say, the forecast is for a larger warming towards the poles.
According to the article, that warming will promote plant growth
(i.e., produce higher yields) by causing more rain -- or, at least, so
long as the warming is less than 3 degrees C or so.
--
Robert J. Chassell GnuPG Key ID: 004B4AC8
[EMAIL PROTECTED] [EMAIL PROTECTED]
http://www.rattlesnake.com http://www.teak.cc
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