Hulme (1995) analysed a database containing records from 8300 gauges throughout the world. He examined changes in different hemispheres and different latitudinal bands for the period 1900 to 1992. Results are shown in Figure 8. The Southern Hemisphere shows a weak trend towards increased precipitation. Within the Northern Hemisphere there is drying in the tropical latitudes (south of 23.4o North) and wetting in the high latitudes (north of 50o North, about the latitude of the south coast of England) in recent decades. Between 23.4o North and 50o North, there has been very little change. The drying in tropical latitudes of the Northern Hemisphere is dominated by the recent desiccation in the Sahel region of Africa.
Observed rainfall trends are qualitatively consistent with the GCM projections, however precipitation is more difficult to monitor than temperature as it varies much more in time and space. There are significant differences in the quality of the data sets and in the construction and efficiency of rain monitoring stations.
