Erosion, salinization, urbanization, and unsustainable agricultural practices are causing desertification in many parts of the planet, according to delegates at a weekend conference in Egypt. Desertification is the process by which the water and nutrients needed to sustain diverse plant and animal life are drained from the soil. British scientist Brian Johnson blamed the problem in part on intensive farming methods such as overgrazing, which reduces the capacity of soil to retain water. About 1 billion people — many of them impoverished — live in the world’s dry areas in Central and West Asia and North Africa, where desertification is most intense, and that number continues to grow. Crops that have been genetically modified to withstand drought and salinization could help reduce hunger problems stemming from desertification and population growth. But many environmentalists see that solution as leaping from the frying pan into the fire, arguing that GM crops haven’t been adequately tested and may have unintended dire consequences for the environment.