The top figure shows dryness trend as measured by the Palmer Drought Severity Index from 1900 to 2002 for different regions of the world. For most areas, drier (red and yellow) conditions are now significantly more common than wetter (blue and green) conditions. The bottom figure shows the trend over time of increasing drought, indicating that for much of the world, droughts are more common.

Source: IPCC AR4, Adapted from Dai et al, (2004)