lightblueline

Tam Hunt over at the Community Environmental Council sent me an article from the Real Climate site with a detailed examination of what's in, what's what, and what's NOT in the recent IPCC report about predicted sea-level rise. The article, submitted March 27th, is a great resource for scientists and others trying to determine how to use the IPCC report.

You can read the whole article here:

The IPCC sea level numbers

One point to note is that the author also suggests that cutting off discussion of sea-level rise to the next 90 years makes little sense if our actions in the coming decade might cause this to continue to rise, and perhaps to rise more dangerously over the subsequent decades and centuries. The point is to do what we can do NOW to limit future sea-level rise to at most, say, one meter. The author's conclusions are below:

"The main conclusion of this analysis is that sea level uncertainty is not smaller now than it was at the time of the TAR, and that quoting the 18-59 cm range of sea level rise, as many media articles have done, is not telling the full story. 59 cm is unfortunately not the “worst case”. It does not include the full ice sheet uncertainty, which could add 20 cm or even more. It does not cover the full “likely” temperature range given in the AR4 (up to 6.4 ºC) – correcting for that could again roughly add 20 15 cm. It does not account for the fact that past sea level rise is underestimated by the models for reasons that are unclear. Considering these issues, a sea level rise exceeding one metre can in my view by no means ruled out. In a completely different analysis, based only on a simple correlation of observed sea level rise and temperature, I came to a similar conclusion. As stated in that paper, my point here is not that I predict that sea level rise will be higher than IPCC suggests, or that the IPCC estimates for sea level are wrong in any way. My point is that in terms of a risk assessment, the uncertainty range that one needs to consider is in my view substantially larger than 18-59 cm.

A final thought: this discussion has all been about sea level rise until the year 2095. Sea level rise does not end there, as the quotes from the SPM at the beginning of this article show. Over several centuries, without serious mitigation efforts we may expect several meters of sea level rise. The Advisory Council on Global Change of the German government (disclosure: I'm a member of this body) in its recent special report on the oceans has proposed to limit long-term sea level rise to a maximum of one meter, as a guard-rail to guide climate policy. But that’s another story."