[ExI] sinking island, was: (asteroid) defense

[Alfio Puglisi]

On Tue, Mar 1, 2011 at 9:55 PM, spike <spike66 at att.net> wrote:

> ... On Behalf Of Damien Sullivan
> Subject: Re: [ExI] libertarian (asteroid) defense
>
> On Tue, Mar 01, 2011 at 10:36:10AM -0800, Samantha Atkins wrote:
>
> >> Please point to irrefutable non-fudged evidence of actually dangerous
> >> levels of current climate change.  Otherwise could we move on to
> >> something actually important?
>
> >Islanders are being evacuated because sealevel rise is destroying their
> property.  Next! -xx- Damien X-)
>
> The sea level hasn't risen enough to cause the evacuation by itself.  The
> island is sinking.
>
> As I recall there is a old city in Europe somewhere that is down at sea
> level.  Venice?  I hear it has been continuously occupied for several
> hundred years.


Make that 1,600 years. The most probable date for the first occupation of
the area is 421 AD. By 1000 AD or whereabouts, Venice was a major naval
power.

  That should provide us with good metrics for what the actual

> sea is doing.
>

Unfortunately the city of Venice is build over a layer of mud, which is not
a stable reference. The city is slowly sinking, in no small part because of
water extraction from the underlying water table. This ingenious activity
has been largely stopped and the sinking has slowed down, but the movement
of the soil is bigger than any recent sea level signature. Moreover, Venice
is in a lagoon with small openings to the sea, and the lagoon has the habit
of making up its own preferred sea level. It's called "acqua alta" (high
water), a kind of large and irregular local tide which forces inhabitants
and unsuspecting tourists to wear their high boots and place wooden boards
between buildings.

Can be entertaining to see, as long as you are somewhere else:
http://commons.wikimedia.org/wiki/File:Acqua_alta_a_Venezia_nel_settembre_2009.jpg


Alfio



>
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