A trend that has already helped accelerate the spread of certain infectious diseases - the northward movement of tropical regions - could become much worse as global warming continues to intensify. In a recently published article in the journal Nature Geoscience, Dian Seidel of NOAA and her colleagues write about signs they observed in the stratosphere that indicate that tropical climate patterns may have expanded by up to 4.5° of latitude in the Northern hemisphere over the past 25 years.
This movement is much more dramatic than the one predicted by prior climate models, which had suggested an expansion of 2° of latitude north and south - within the next century. To discover this worrying trend, Seidel and her fellow researchers studied five sets of data from 1979 to 2000 containing information about tropical climate pattern indicators, such as ozone concentrations and temperatures. Both were seen to increase, suggesting an expanding tropical belt.Seidel attributes the large discrepancy between her study's predictions and those made by other climate models to the impact of the stratosphere, which doesn't tend to be well represented in models. Aside from subjecting subtropical and temperate ecosystems to tremendous pressure, Seidel is worried about the unpredictable effects the migrating tropical belt will have on the spread of vectors, such as mosquitoes, and infectious diseases.
Via ::Science: Tropics on the Move (news website), ::National Geographic News: Climate Change Pushing Tropics Farther, Faster (news website)