He neglects to note that virtually all of the papers on this topic presented at last month's international conference on statistical climatology in Luneburg, Germany, reported that the pattern is largely consistent. He does correctly report that the current best estimates by the Intergovernmental Panel on Climate Change, a large international scientific review under United Nations and World Meteorological Organization sponsorship, are that average warming over the coming century will be between 2.5 to 10.4 degrees Fahrenheit. However, he then claims that when used properly, global climate models predict that there will be only 2.5 degrees of average warming. The dozens of co-authors of the IPCC report he cites include many of the scientists who developed those models, and presumably know how best to use them. Average sea level rose between 4 and 8 inches during the past century, but not, as Mr. Kelly suggests, mainly because of melting ice.
Water expands a little bit when it is heated, and like the atmosphere, the oceans are warming.
IPCC estimates of the amount of sea level rise that will occur this century range up to as high as 40 inches. This may not be enough to drown the Statue of Liberty, as some tabloid journalists have suggested, but it is enough to produce devastating flooding in many small island nations, and when combined with storm surge, cause serious damage to coastal buildings, infrastructure like the New York airports and tunnels, and salt marshes. But there is dispute over what causes it, and whether, on balance, it would be harmful. The issue of whether global warming will be harmful is a matter of values, not science. The impact during this century on the economy of the United States and other developed countries will likely be just a few percent or less.