Have we forgotten the Galveston hurricane of 1900?
Bob at PC
________________________________________
From: Phys-l [phys-l-bounces@mail.phys-l.org] on behalf of John Denker via Phys-l [phys-l@mail.phys-l.org]
Sent: Thursday, August 31, 2017 8:51 AM
To: Forum for Physics Educators
Cc: John Denker
Subject: [Phys-L] in the news: energy versus temperature
Hi Folks --
Here's a lesson about the difference between energy and
temperature, and about why you should care.
The surface temperature of the Gulf of Mexico last week
was warm, but not warm enough to explain, by itself, the
strength of Hurricane Harvey.
It turns out the interesting question is energy, not surface
temperature.
Back in the olden days, the Gulf would have a *thin* layer
of warm water at the surface. This would feed storms, but
as soon as the storm got going it would stir things up,
mixing in cooler water from below, and the storm would
effectively blow itself out.
Nowadays, however, the warmth extends much deeper into
the water column. So the storm can persist much longer.
Back in the olden days, the storm surge from a powerful
storm could wipe out a coastal city in a couple of hours.
Conventional wisdom was that the storm surge was the
thing to worry about. So people built barriers to keep
it out.
That wasn't what happened with Harvey. The storm surge
wasn't what got Houston. The problem was fresh water,
not salt water, and it arrived over the course of days,
not hours. Coastal barriers don't do any good when you
get 50 inches of rain falling on the supposedly-protected
side of the barriers.
All this was completely foreseeable, and indeed foreseen.
Houston was warned, again and again, year after year, that
they needed to do more in terms of flood abatement, but
they did virtually nothing. Not even a building code to
discourage people from building in low-lying areas. Also
they persisted in using out-of-date planning maps. One
neighborhood in Houston is /outside/ the 500-year floodplain,
according to the "official" maps, yet has flooded three times
in the last ten years. Prof. Poisson tells me the chance of
that happening randomly is about one in a million.
I wonder how many 200-billion-dollar losses people have to
sustain before they start taking climate change seriously.
As the saying goes, $200 billion here, $200 billion there,
and pretty soon it adds up to real money.