Predicting future sea level rise
The two main contributors to sea level rise are thermal expansion of water and melting ice. Predicting the future contribution from melting ice is problematic. Most sea level rise from ice melt actually comes from chunks of ice breaking off into the ocean, then melting. This calving process is accelerated by warming but the dynamic processes are not strongly understood. For this reason, the IPCC didn’t include the effects of dynamic processes, arguing they couldn’t be modelled. In 2001, the IPCC Third Assessment Report (TAR) projected a sea level rise of 20 to 70 cm by 2100. In 2007, the IPCC Fourth Assessment Report (4AR) gave similar results, projecting sea level rise of 18 to 59 cm by 2100.
Figure 1: Sea level change. Tide gauge data are indicated in red and satellite data in blue. The grey band shows the projections of the IPCC Third Assessment report (Allison et al 2009).
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