From the West Nile virus that found its way to New York last year to an epidemic of cholera, malaria and Rift Valley fever spawned by flooding in the Horn of Africa, the evidence of global warming on human health is everywhere, according to Paul Epstein, associate director of the Center for Health and the Global Environment at Harvard Medical School. As the atmosphere has warmed over the past century, droughts in arid areas have persisted longer, and massive bursts of precipitation have become more common. It may kill fewer people in one fell swoop than a raging flood or an extended drought, but once it takes root in a community, it often defies eradication and can invade other areas. This shortfall has serious implications for the rest of the world, Epstein said. Mosquitos are notorious for carrying and speading infectious diseases.
Mosquitoes breed faster and bite more as the air warms up.
Warmer temperatures also increase the rate that pathogens inside them reproduce and mature. As whole areas heat up, then, mosquitoes could expand into formerly forbidden territories, bringing illness with them. Floods and droughts also trigger outbreaks of infectious diseases by creating breeding grounds for insects whose desiccated eggs remain viable and hatch in still water. Malaria and dengue fever are two mosquito-borne diseases most likely to spread as global temperatures increase. Malaria already kills 3,000 people, mostly children, every day.