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Professor Robert Balling, Arizona State University, USA,

spoke about the inter-relationships between the global climate system, drought and desertification, including the impact of desertification on climate change and global warming. The first part of his presentation addressed what is known about climate in the drylands. The major characteristic of dryland climates is their unusual variability. Precipitation varies from season to season and year to year and consistent cycles are not typically found in dryland rainfall data. He then addressed the question of whether dryland droughts can be predicted. Dryland precipitation levels are linked statistically to sea surface conditions, the impact of El Ni´┐Żo and southern oscillation events, general atmospheric circulation patterns, solar patterns, volcanic eruptions, typhoons and hurricanes. At this point scientists understand what is driving the climate patterns in drylands and can predict the rainfall in seasons, if not in months. Human activities have impacted the surface and atmosphere in drylands primarily by reducing vegetation cover through overgrazing and cultivation practices. He elaborated on the scientific debate on the relationship between a decrease in soil and vegetative cover and climate change. He commented that drylands are not major emitters of greenhouse gases or major carbon sinks. Climate change is bad news for drylands where temperatures may increase by 2-5 degrees.