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Re: [Phys-l] Global Warming



I know arguing from authority is frowned upon, but William
Gray has taken a stand on the issue: the current trend, in
his view, is due more to natural cycles, and the effect of
human activity is minimal. Just do a Google with his name
and global warming. He certainly qualifies as someone who's
opinion should be considered given his experience with
modeling ocean/atmosphere vis-a-vis hurricanes.

I don't know William Gray but I am familiar with Kerry Emmanual,
professor of meteorology at the Massachusetts Institute of Technology,
author of the book, Divine Wind. I have a lot of respect for him and
this is what he says (from
<http://www.democracynow.org/article.pl?sid=05/08/29/145206>):

AMY GOODMAN: And for those who criticize you, those scientists like
William Gray of Colorado State, saying that hurricanes are not
intensifying and that the cause of rising ocean temperature is natural,
not man-made?

KERRY EMMANUEL: Well, Bill has spent his career looking at the Atlantic
hurricanes. And I want to emphasize again that the Atlantic is only 11%
of the total. If you look at the Atlantic, it's perfectly fair to say
that both the increase in ocean temperature in the last couple of
decades and the upswing in hurricane activity is mostly natural. If
there's a global warming signal in that, it's very hard to see. And that
natural cycle, we don't fully understand it, by the way, I don't think
anyone pretends that we do, but there have been in history, you know,
periods of 20 or 30 years of inactivity followed by 20 or 30 years of
activity. It's nothing new, in fact. Before the 1990s, a lot of
hurricane specialists had forecasts that we were going to go back to an
active period in the Atlantic, and again, this has nothing to do with
global warming.

So, when you focus on the Atlantic, it's the natural cycles that are the
big thing, at least up until now. And I don't think anybody, certainly I
wouldn't look the at the Atlantic record all by itself and say, oh,
there's global warming. It's when you look at the global record of
storms that this signal really starts to stand out. And we're interested
in that, of course, because we're interested in how the climate responds
to global warming. But there is the other question of what does this
mean for actual damage done by hurricanes? And the surprising answer is
that in the last -- next 20 years or so, probably not much, simply
because of statistics. I mean, big hurricanes hitting land are a
comparatively unusual phenomenon, only a few per year globally. And you
just don't expect to see a trend like this in the land-falling
statistics, at least not for another 50 years or so.

----------------------------------------------------------
Robert A. Cohen, Department of Physics, East Stroudsburg University
570.422.3428 rcohen@po-box.esu.edu http://www.esu.edu/~bbq