[Coral-List] Atolls and SL rise
Bill Allison
allison.billiam at gmail.com
Tue Oct 5 05:41:47 EDT 2010
Here is what the German public is being treated to:
http://www.spiegel.de/international/world/0,1518,707884,00.html
On Tue, Oct 5, 2010 at 2:09 PM, Richard Dunne <RichardPDunne at aol.com> wrote:
> Dear Listers and Bill
>
> Bill makes a very valid point for the seasonal influences in the Maldives
> where (particularly in the northern islands) there is a significant
> difference as Han et al point out. However, further south in the Chagos for
> example, this is not the case. The Han et al model shows a lot of
> heterogeneity both overall and seasonally throughout the Indian Ocean which
> emphasises the regional nature of long term sea-level changes.
>
> Richard P Dunne
>
>
> On 05/10/2010 03:13, Bill Allison wrote:
>
>>
>> As I pointed out in my post of Sep 30, 2010, Han et al. (2010) also
>> suggested on page 549 that seasonal variation in sea level could have
>> significant effects.
>>
>> "However, statistically significant sea-level rise is shown during winter
>> in both ocean general circulation models and Simple Ocean Data Assimilation
>> data (Supplementary Fig. S2), which could have significant impacts on the
>> Maldives because of its low elevation." p. 549
>>
>> Factor in storm surge or a tsunami riding on the back of such variation
>> and the risk increases appreciably.
>>
>>
>>
>> On Mon, Oct 4, 2010 at 7:41 AM, Richard Dunne <RichardPDunne at aol.com<mailto:
>> RichardPDunne at aol.com>> wrote:
>>
>> Dear Paul and List
>>
>> By casting aside the more recent evidence from Han et al 2010 (Nature
>> Geoscience) into the category of "a little absurd" you fail to
>> distinguish between regional sea-level rise and globally averaged
>> effects, between analysis which incorporate regional ocean-atmosphere
>> circulation changes and which do not, between examination of recent
>> (from the 1960s up to 2008) rates of change, and those incorporating
>> semi-empirical modelled and predicted events. These things cannot be
>> easily resolved or selectively dismissed in this way.
>>
>> Han et al. conclude "Our results indicate that warming-induced
>> regional
>> atmospheric circulation changes - although challenging for climate
>> models, especially over the Indian monsoon region - should be
>> considered
>> seriously, together with thermal expansion, melting land ice and
>> natural
>> variability, to achieve reliable regional sea-level and climate
>> prediction."
>>
>> A recent comprehensive review of of sea-level rise by Cazenave &
>> Llovel
>> (Annual Reviews of Marine Science 2010) considers an earlier paper by
>> Rahmstorf (2007) which like the recent Vermeer & Rahmstorf (2009)
>> produced comparable values of between 50 and 120cm by 2100, describing
>> it as "offering plausible ranges of future sea-level rise and an
>> interesting alternative to still uncertain coupled climate model
>> projections.".
>>
>> Also, if it is indeed "widely accepted" as you say, that the IPCC AR4
>> (AB1) scenario for future globally averaged sea-level rise is a
>> serious
>> underestimation then why for example do the eminent scientists of the
>> Royal Society (Climate change: a summary of the science. Sept
>> 2010) not
>> share these views? There is no evidence that they accept the large
>> values that you cite, quite the contrary. They conclude that
>> "Because of
>> the thermal expansion of the ocean, it is very likely that for many
>> centuries the rate of global sea-level rise will be at least as
>> large as
>> the rate of 20 cm per century that has been observed over the past
>> century." and "There is currently insufficient understanding of the
>> enhanced melting and retreat of the ice sheets on Greenland and West
>> Antarctica to predict exactly how much the rate of sea level rise will
>> increase above that observed in the past century for a given
>> temperature
>> increase."
>>
>> This is, and remains an area of considerable uncertainty and
>> controversy
>> and I dare say will remain so until a reliable longer term dataset has
>> accumulated. In the meantime we should be cautious to oversimplify the
>> issues involved and close our minds to all the alternatives.
>>
>> Richard P Dunne
>>
>>
>>
>>
>> On 03/10/2010 05:08, Paul Blanchon wrote:
>> > Dear Richard and list,
>> >
>> > The argument that some atolls "may survive for generations" and
>> > should be considered for re-population seems just a little absurd,
>> > regardless of the politics.
>> > It is widely accepted that not only is the IPCC AR4 prediction of SL
>> > rise a serious underestimation, but that over the last few decades
>> > "...sea level has in fact risen 50% more than predicted by its
>> > models..." (see the illuminating climate-science blog at:
>> >
>> www.realclimate.org/index.php/archives/2010/03/ippc-sealevel-gate/
>> <
>> http://www.realclimate.org/index.php/archives/2010/03/ippc-sealevel-gate/>).
>>
>>
>> >
>> > The IPCC underestimation has been the subject of several subsequent
>> > publications which all conclude SL rise by 2100 will likely
>> exceed one
>> > meter: for example, Vermeer and Rahmstorf 2009 (PNAS 106:
>> 21527-21532)
>> > predict average rates over the 21st century will be 8-18 mm/year.
>> > Thus, as Chip Fletcher implies, the experience of Micronesians is
>> > likely to be repeated in all low-lying coastal communities,
>> regardless
>> > of past or future regional variation.
>> >
>> > Re-population of any atoll would therefore seem to be an
>> exceptionally bad idea.
>> >
>> > Saludos,
>> > Paul.
>> >
>> > Paul Blanchon
>> > Marine Geoscience Lab.,
>> > Reef Systems Unit,
>> > Institute of Marine Sciences& Limnology
>> > National Autonomous University of Mexico
>> > Tel. +52 (998) 87-10009 Ext 166
>> > _______________________________________________
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>>
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>>
>>
>> --
>> ________________________________
>> "reality leaves a lot to the imagination..." John Lennon
>>
>
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"reality leaves a lot to the imagination..." John Lennon
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