Browsing this months UK Climate Impacts Programme (UKCIP) newsletter I was pleased to see a recent analysis of sea level rise:

http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=214&Itemid=482

Title:
Pfeffer, W. T., Harper, J. T. & O'Neel, S. (2008), "Kinematic constraints on glacier contributions to 21st-Century sea-level rise," Science, 321, 1340-1343

Text:
"The IPPC AR4 estimates global (Eustatic) sea level rise (SLR) by 2100 to be between 0.18-0.6m"

"dynamically forced discharge, via fast flow and calving of marine terminated moraines (glacial deposited sediments) has been observed in Greenland, leading to rapid land-ocean transfer of ice" [nb this is where the media hysteria of 20m SLR comes from, as widely promoted by Al Gore]

"In order to try to take some account of these processes modelling, and Palaeoclimate (sediment and ice core indicators of climate history) comparisons have been undertaken. These suggested that sea levels are capable of rising by several meters within a century, leading to concerns that multiple meter SLR might occur during the coming century."

Ok pause for a minute. Comparisons of core indicators of climate history 'suggested sea levels are capable of rising by several meters within a century' without human influence. The typical AGW reponse is of course, what will happen with human influence? We'll come to that shortly. The point is that these climatic changes have occurred without human influence. I'll say it again because it feels nice to swirl this around: These climatic changes have occurred in the past without human influence.

"This paper addresses the plausibility of very rapid SLR from land ice occurring this century."

"The velocities required for very large increases in sea level (2-5 m) are found to be far beyond the range of observations, and while no physical proof is offered that these velocities cannot be reached, the authors recommend that they should not be adopted as a central working hypothesis."

Another pause for emphasis: the authors recommend that SLR of 2-5m should not be adopted as a central working hypothesis

"On the basis of their calculations the authors therefore suggest that an improved estimate of the range of SLR to 2100 taking account of increased ice dynamics lies between a 0.8 and 2.0 m increase."

It should also be noted that the estimates of the authors seem to be less than one meter; the two meter rise "combines all eustatic sources taken as high but reasonable values".

This is not unknown to the authorities in this country. At a private dinner to discuss ways to encourage the public to engage with climate change, I asked a very senior UK authority on all things environmental why we're not planning to build a new Thames barrier - surely this would be the clearest signal we could send to the public? The response was that all the models show that the current Thames barrier is sufficient to deal with any SLR to at least 2050 but probably many years beyond that. Shall I say it again? Well, perhaps just a little emphasis.

Two final things: firstly, let's average this out over the remaining 91 years:

0.8m by 2100 = 0.009m, or roughly 0.9cm per year.
2.0m by 2100 = 0.02m, or roughly 2 cm per year.

Of course, this rise will be location dependent due to the not-quite-spherical nature of the Earth. Given time I will try to find some info on regionality.

Secondly, what does this mean in practical terms? Basically it means a bit of flood defence should sort most of us out ok. We should do this whether we reduce CO2 emissions or not, it is simply common sense - see the pause above. It also means some low-level countries will be at risk. See my post here:
http://bumface.blog.co.uk/2008/10/06/lomborg-1-pachauri-4829607