Paul R. Epstein, MD, MPH, is Associate Director of the Center for Health and Global Environment at Harvard Medical School and a medical doctor trained in tropical health. He contributed to the work of the Intergovernmental Panel on Climate Change, which was awarded the Nobel Peace Prize in 2007.Dan Ferberis a contributing correspondent forSciencemagazine. His feature articles have appeared in many publications, includingPopular Science, Audubon,andNature Conservancy.