World population growth is slowing down. By 2050, there will be approximately 9 billion people on Earth, and by 2100, there will be about 10 billion. However, after that, many demographers believe that the world's population will plateau or perhaps even decrease. Still, food shortages are a potential threat if agricultural output doesn't double by 2050. Unfortunately, a new analysis in PLoS ONE suggests that current crop yield trends are falling well short of this goal.