China said Tuesday it was winning the struggle against encroaching deserts, with the threat to vulnerable land steadily decreasing over the past half-decade.

Tens of millions of people could be driven from their homes by encroaching deserts, particularly in sub-Saharan Africa and Central Asia. The study by the United Nations University suggests climate change is making desertification "the greatest environmental challenge of our times."

Half a century after Mao Zedong’s “Great Leap Forward” brought irrigation to the arid grasslands in this remote corner of northwest China, the government is giving up on its attempt to make a breadbasket out of what has increasingly become a stretch of scrub and sand dunes.

Scientists are looking at the potential for rapid climate change to create droughts. Droughts have affected all areas of the world, and could become more common.