ENB:04:11
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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¤o 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.