Map of Greenland Ice Sheet
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 heGuardian Environment Network.
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.
The IPCC's 2007 sea level calculations — widely recognized by the academic community as a critical flaw in the report — have caused confusion among many in the general public and the media and have created fodder for global warming skeptics. But there should be no confusion about the serious threat posed by rising sea levels, especially as evidence has mounted in the past two years of the accelerated pace of melting of the Greenland and West Antarctic ice sheets.
Most climate scientists believe melting of the Greenland Ice Sheet will be one of the main drivers of sea level rise during this century.
The message for the world's leaders and decision makers is that sea level rise is real and is only going to get worse. Indeed, we make the case in our recent book, The Rising Sea, that governments and coastal managers should assume the inevitability of a seven-foot rise in sea level. This number is not a prediction.