Getting warmer

Natural History, Sept, 2004 by Spencer R. Weart

In his review of my book The Discovery of Global Warming ("Heat Exchange" 4/04), Robert Ehrlich asks why I did not mention satellite data on global temperatures, which "show a much smaller increase in global warming than do measurements at ground stations or projections based on computer climate models." My answer is that I was reluctant to devote space to the arcane technical interpretations of such data because most scientists find the subject suspiciously complex and uncertain. My hesitancy appears justified by the results of more recent studies, which indicate that the satellite measurements have underestimated tropospheric warming. It now appears that these data offer no support to the position of those who would deny the probability of global warming.

Mr. Ehrlich and I agree that some global warming is highly likely, that we can't know for sure whether that will cause severe damage within our lifetimes, and that we can take steps now that will retard the warming without harm to--even with benefit to--the economy.

Spencer R. Weart

American Institute of Physics

College Park, Maryland