A paper in 1991 claimed that regions affected by desertification experience warming trends relative to neighboring areas. To assess this, an index of aridity/humidity based on the ratio of annual precipitation to annual potential evapotranspiration totals (P/PET) is developed. This index is used to define regions experiencing increases (and those where the increase is statistically significant) in aridity and humidity. We also consider regions always arid (average values of P/PET2.0). Trends of average annual and summer surface air temperature are then calculated for regions in the various aridity/humidity categories and compared to most of the rest of the world's land areas equatorward of 60¿. The results indicate that most of the differences in trends between categories are not statistically significant. ¿ 2001 American Geophysical Union