The Sahara Desert has expanded by about 10 percent since 1920, according to a new study by National Science Foundation (NSF)-funded scientists at the University of Maryland (UMD).The research is the first to assess century-scale changes to the boundaries of the world's largest desert. It suggests that other deserts could be expanding as well. The study is published today in the Journal of Climate."The trends in Africa of hot summers getting hotter and rainy seasons drying out are linked with factors that include increasing greenhouse gases and aerosols in the atmosphere," says Ming Cai, a program director in NSF's Division of Atmospheric and Geospace Sciences, which funded the research. "These trends have a devastating effect on the lives of African people, who depend on agriculture-based economies."