Will a Warmer World Make Us Sicker?
Scientists are piecing together how climate impacts disease, strange patterns are emerging: mosquito outbreaks can follow drought, shorter migrations can make butterflies sick, and more birds (not fewer) can ward off West Nile virus.
by Roberta Kwok
From Conservation magazine, part of the Guardian Environment Network:
In the late 1990s, a set of alarming maps created a stir in the scientific community. Based on predictions by a team of Dutch and Australian researchers and initially published in the journal Environmental Health Perspectives, the maps charted how global warming could increase the risk of malaria in seemingly unlikely locales: northern countries such as Poland, the Netherlands, and Russia.
Over the next several years, versions of the maps continued to appear in journals and at scientific meetings as researchers raised the disquieting possibility that climate change could trigger an expansion of disease. An article in Scientific American reprinted one iteration of the maps and declared that "by the end of the 21st century, ongoing warming will have enlarged the zone of potential malaria transmission from an area containing 45 percent of the world's population to an area containing about 60 percent." Statements like these added to the popular perception that a warmer world will automatically be a sicker one.
But what if this isn't true, or is only partially true? Kevin Lafferty, an ecologist at the U.S. Geological Survey, is among a handful of scientists now raising these questions and rethinking conventional wisdom. Lafferty recently published a controversial article in the journal Ecology suggesting that, while climate change may shift the ranges of certain diseases, it won't necessarily increase the total amount of territory they affect. (1) And Sarah Randolph, a parasite ecologist at the University of Oxford, has reviewed recent disease outbreaks-some of which have been attributed to global warming-and concluded that human actions and other factors may have played a larger role than climate.
Lafferty's and Randolph's opinions have stirred intense debate. While there are credible arguments on both sides, the overriding point is that some scientists are beginning to see the ecology of disease as far too complicated to support simple declarations about the impact of global warming. It turns out that disease ecology is made up of a multitude of moving parts, ranging from precipitation patterns to animal migrations, that constantly shift and adjust in relation to each other. And when climate changes, the end result may be an increase in disease-or not.
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http://www.commondreams.org/headline/2009/08/03-3