To the Editor.
—Readers of JAMA deserve a balanced account on whether global warming (because of increases in greenhouse gases) will be good or bad for human health. The article by Dr Patz and colleagues1 fails to do this.First, dealing with climate science, the article presents ice core data of carbon dioxide (CO2) and temperature for the last 180 000 years (Figure 1) and notes the close correlation, implying that past increases of CO2 have led to strong warming and that the current increase will do the same. This is misleading. Readers should be warned that the compressed time scale (100000 years per inch) cannot show the cases where temperature increases preceded the CO2 increases. Nevertheless, one can discern a CO2 increase 125 000 years ago associated with a drop in temperature.Figure 1 in the article shows a dramatic (projected) doubling of CO2, but the