New Scientist, Issue 2699 (14 March 2009) carries a rather confusing news story that reports that recent measurements show that sea level has been rising by 3 millimetres per year since 1993 which is higher than the 2007 forecast of the Intergovernmental Panel on Climate Change (IPCC). It seems that the differences comes from melting from the Greenland and Antarctic ice sheets which was not included in the IPCC forecast because of uncertainty over the models used to predict this. The IPCC forecast was for a sea level rise of 18-59 centimetres by 2100 but apparently if the current trend continues a rise of 1 metre or more by 2100 is likely. However, if you take the 3mm per year figure from the current measurements and extrapolate this out to 2100 you get a rise of about 27 cm (that’s 3 mm/year x 90 years = 270 mm = 27 cm) which is slap-bang in the lower-middle part of the 2007 IPCC forecast range. So, where’s the story gone…?
Tim O'Hare 