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A DRAMATIC global shift in the world’s climate may have turned an area
covered with rivers and lakes into one of the driest places on Earth. Scientists
were convinced the Atacama Desert in western South America formed more than 10
million years ago when the Andes grew high enough to keep moist air out. But a
new study led by geologist Adrian Hartley of the University of Aberdeen is
challenging this interpretation. He says the Atacama region actually stayed wet
until around 3 million years ago (Geology, vol 30, p 43). This is when
the African deserts formed, which suggests that the southern
hemisphere—and possibly the entire globe—fell victim to the climate
change that created these great deserts.