Current climate models fail to replicate past droughts

Nature : Atmospheric and oceanic dynamics are so complex that it is difficult to predict the next major drought in the US Southwest, concludes Sloan Coats of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York, and his colleagues. They presented their findings last week at the annual assembly of the European Geosciences Union in Vienna. To test their state-of-the-art climate model, they input such data as atmospheric carbon dioxide levels, changes in solar radiation and ash from volcanic eruptions, and changes in the El NiñoâSouthern Oscillation and then compared the results with data from the North American Drought Atlas. What they found was that although their model predicted several major, decades-long droughts, they did not coincide with the actual droughts that occurred. The researchers conclude that El Niño and La Niña events, clouds, and vegetation can all influence rainfall but are too complex for current models to anticipate their precise effects on the climate. Despite the fact that climate models fall short on predicting particular events, however, they all agree that the US Southwest is going to get warmer and drier over time.