Friday, 14 November 2008

How good are global river flow predictions?

We recently highlighted findings on changes in future river flows predicted in a General Circulation Model (GCM). A key aspect of any predictions of future climate impacts is the skill and confidence with which they can be applied.

Recent work has investigated how river flow predictions in the Met Office Hadley Centre Global Environmental Model (HadGEM1) compare to flow gauge measurements around the world. These generally showed surprisingly good skill, given the limitations of coarse resolution and the driving GCM climate, rather than observed climate.

There is more work to be done to understand the detail - such as whether errors result from the river flow model itself, or mostly from the hydrology supplied to the model.

In addition to uncertainties in predicting observed changes, there are a number of sources of uncertainty in climate predictions which need to be addressed. With a better understanding of these uncertainties, it should be possible to develop nearer term predictions of impacts relevant to water and agriculture.