The School of Earth and Atmospheric Sciences Presents Dr. Rob Chadwick, UK Met Office

How Does the Tropical Water Cycle Respond to Climate Change?

Many tropical countries are exceptionally vulnerable to changes in rainfall patterns, with floods or droughts often severely affecting human life and health, food and water supplies, ecosystems and infrastructure. However, there is widespread disagreement among climate model projections of how and where annual or seasonal mean rainfall will change over tropical land.

This disagreement is largely caused by the diversity of climate model responses of the atmospheric circulation to warming, with different models predicting current tropical wet and dry regions to shift in different ways. Changes in the frequency and intensity of daily rainfall are more robust in climate projections, but are not physically well understood or well constrained by observations.

In order to reduce uncertainty in these projections, and to provide more robust advice on climate change impacts, the processes that drive changes in the tropical water cycle need to be better understood. A hierarchy of simple and complex models have been used to examine these processes, and these results give some insight into regional climate change in the tropics.