Re: global warming effect on coast

From: Ian St. John (istjohn_at_noemail.ca)
Date: 06/21/04 

Date: Mon, 21 Jun 2004 15:44:04 -0400

steve wrote:
> Josh Halpern wrote:
>
<snip>
>> There go the US East Coast Barrier Islands, and Bangladesh....
>
>
> Cummulative longwave forcing is approaching an equivalent
> doubling of CO2.

And yet CO2 has increases about 30%. Can you explain your reasoning?

>
> The rationale that temperatures have not risen as modeled
> is that the oceans are absorbing the additional heat.

That is true, and the current 2.6 cm/decade rise in sea level is mostly due
to this. Influx of water from glacial melt is only about 10% of the rise.

>
> If that is not so, the models appear in serious error.
>
> If that is so, thermal expansion of the oceans should
> already be in high gear

Not so, as the effect takes time and the forcing is still lagged.

> and high gear amounts to eight inches
> a century from now.

That depends. The current rise of 2.56 cm/decade, if steady, would result in
24.5cm rise from thermal expansion alone ( greater than the 8"/20cm you
claim). This is, however, not the complete story and there is no indication
that the current thermal expansion rate will hold steady as the greenhouse
warming increases in intensity ( up to the doubling )

http://www.grida.no/climate/ipcc_tar/wg1/428.htm

The range of possible results from the IPCC is from 11cm to 77cm with 49cm
( about a half meter ) the most likely. It is to note that the lagged
warming of the oceans ( the heat only penetrates so far quickly ) will
continue and the total rise from thermal expansion is predicted to be
anywhere from three times to nine times the early value ( in 500 years ).

However, their is also the fact that ice sheets, not taken into account
here, may contribute much more than their current value if they destabilise.
It is not out of the question to have Greenland lose a fair portion of it's
ice *** over the next century ( it lost it nearly entirely in both of the
last two interglacials ) under the effect of the positive NAO. IT was noted
to be losing 50 cubic kilometers per year recently just due to melting. And
the WAIS is considered at risk because it is grounded below sea level. A
change of .5meters may be enough to destabilise it and cause the start of a
breakup.

It is interesting to look at the USGS website on sea level and their notes
on ice *** vs sea level.
http://pubs.usgs.gov/fs/fs2-00/
"Sea levels during several previous interglacials were about 3 to as much as
20 meters higher than current sea level."
"Reduction of the West Antarctic and Greenland ice sheets similar to past
reductions would cause sea level to rise 10 or more meters. A sea-level rise
of 10 meters would flood about 25 percent of the U.S. population, with the
major impact being mostly on the people and infrastructures in the Gulf and
East Coast States (fig. 3). "

Since these sea level changes happened 'naturally' in the last two
interglacials, the most GW could do is make them happen *faster*. And
nothing we can do will stop them, expecially if we keep 'pouring on the
heat'.

> http://www.jason.oceanobs.com/images/actualites/applis/niv_moy.gif
>
> Clean water, immmunizations, education and political stability
> would appear to be far greater concerns than sea level for
> Bangladeshis.

Reductions in fascist ideology, removal of bible based curriculums,
suppression of tired racial bias based rants, and a return to principles
like honesty and fair play would appear to be far greater concern than
Bangladesh for Americans.

Looks like "steve" could be a test case to see if such improvements are
possible.

>
>
>>
>> josh halpern

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