More Frogs, Fewer Monarchs

First it was rising seas and altered weather. Now, say experts writing in Science, global warming is helping spread disease as well--not just in humans but also in oysters, butterflies, birds and plants. Says co-author Richard Ostfeld of the Institute of Ecosystem Studies in Millbrook, N.Y.: "The evidence cuts across so many diseases and organisms that it has us quite alarmed."

Part of the danger comes from pests that carry such illnesses as malaria, dengue fever and Lyme disease, which are expanding their ranges from the tropics toward the poles or to higher altitudes. Parasites like warm weather too: a tiny protozoan that breeds between the abdominal scales of monarch butterflies is just one example.

The news is not all bad: some fungi, including those that are wiping out frogs in Australia and Central America, are happier in cool weather. But on balance, says Ostfeld, "a warmer world will be a sicker world." --A.D. and M.D.L.