Get ready for seven-foot sea level rise as climate change melts ice sheets

The IPCC's 2007 report missed out the melting of the Greenland and West Antarctic ice sheets which would be the key drivers in dramatic sea level rises. From Yale Environment 360, part of the Guardian Environment Network

Rob Young and Orrin Pilkey for Yale Environment 360, part of the Guardian Environment Network
guardian.co.uk, Friday 15 January 2010 11.57 GMT

The reports from the Intergovernmental Panel on Climate Change (IPCC) are balanced and comprehensive documents summarizing the impact of global warming on the planet. But they are not without imperfections, and one of the most notable was the analysis of future sea level rise contained in the latest report, issued in 2007.

Given the complexities of forecasting how much the melting of the Greenland and West Antarctic ice sheets will contribute to increases in global sea level, the IPCC chose not to include these giant ice masses in their calculations, thus ignoring what is likely to be the most important source of sea level rise in the 21st century. Arguing that too little was understood about ice sheet collapse to construct a mathematical model upon which even a rough estimate could be based, the IPCC came up with sea level predictions using thermal expansion of the oceans and melting of mountain glaciers outside the poles. Its results were predictably conservative — a maximum of a two-foot rise this century — and were even a foot lower than an earlier IPCC report that factored in some melting of Greenland's ice sheet.