Comments on: Provoking comment and framing risk http://2risk.wordpress.com/2012/07/30/provoking-comment-and-framing-risk/ Science, policy and decision-making Mon, 27 May 2013 12:32:35 +0000 hourly 1 http://wordpress.com/ By: Brian http://2risk.wordpress.com/2012/07/30/provoking-comment-and-framing-risk/#comment-685 Thu, 02 Aug 2012 15:38:45 +0000 http://2risk.wordpress.com/?p=681#comment-685 Sorry for the delay in commenting. I thought I’d throw in a couple of links to recent material on sea level rise which support the notion that we need to concentrate on mitigation as well as adaptation, and there is a premium on acting now. It seems to me that your earth scientist correspondent desires a relaxed and comfortable life.Depending on his age he may be granted his wish. If he has grandchildren, however, he should have a thought for his grandchildren’s grandchildren, and indeed their grandchildren.

The first reference is to a paper by Schaeffer et al which looks at the implications for sea level rise up to 2300 for several scenarios. You need to follow the links to understand what the scenarios mean, but in broad terms RCP4.5 refers to stabilisation at forcing of 4.5W per square metre, or 650ppm CO2e. RCP3-PD means 450ppm CO2e, which is roughly where we are now.

Their conclusions are disturbing. They find, for example, that a 2 °C warming limit would probably see many metres of sea level rise in oncoming centuries, and would maintain rates of SLR higher than today for many centuries. SLR of 1.5m is virtually unavoidable and could only be limited to that by “large-scale deployment of CO2-removal technologies”.

The second reference is to an OECD study looking at the exposure of 136 port cities with more than a million population to the risk of a 1 in 100 years storm event. Go to this post by Alex Kasdin and follow the links.

The study looked at the risk exposure now and in 2070, taking into account changes in population, half a metre of sea level rise, subsidence where relevant, and expected increased storminess. They looked at “exposure” on the assumption that adaptation measures don’t exist. Essentially because it would have been too complicated, and pointing out that such measures may in fact fail as they did in New Orleans.

Right now $3 trillion worth of property and 40 million people are exposed. By 2070 those numbers become $35 trillion (roughly 9% of forecast world GDP) and 147 million (not 120 million as stated in the post). They point out that there is a 74% chance of one or more of these cities being impacted by a once in a century event every year. I’m not sure whether they take account of the notion that what is now a 1 in 100 event becomes much more frequent with half a metre of SLR. Their “increased storminess” refers to the expected increased intensity of severe storms.

That’s what is in prospect for today’s children’s grandchildren, or rather just on aspect of what they will probably experience.

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