Rainfall

Climate change is not just about changes in temperature. The whole water cycle is also affected.

A warmer world means the atmosphere has the capacity to hold greater moisture.

So there are changes in the amount of water vapour, rainfall and the circulation of water in the atmosphere.

Rainfall has many characteristics, including amount, frequency, intensity and type.

Long term changes in rainfall have been observed. The 20th Century has seen an increase in precipitation in Northern latitudes, but a downward trend in the tropics, particularly after the mid-1970s.

Areas that have seen an overall reduction in precipitation are also likely to have seen an increase in heavy rainfall events.

The maps and data shown here cover the period 1985 to 1999, represented as individual months and yearly average. There are global maps, maps for 18 of the world’s major river basins.

The maps make it possible to visualise the changes over a season as well as the year to year changes.