sky higher

The sky is rising and human-caused changes in ozone and greenhouse gases are largely to blame, say researchers in the July 25 Science. The height of the tropopause — the boundary between the stratosphere and the troposphere, the atmosphere’s lowest layer that extends to the Earth’s surface — has risen by almost 700 feet since 1979. The tropopause is important because it plays an active role in the development of weather systems, said Brian Hoskins of the University of Reading’s Department of Meteorology in a related article. B. D. Santer of the Lawrence Livermore National Laboratory in California and colleagues used weather forecasts and other data from the past 20 years to computer-model a series of atmospheric simulations. The researchers discovered that greenhouse-gas warming in the troposphere and ozone-related cooling in the stratosphere accounted for about 80 percent of the rise. Hoskins writes, “Continuing changes in the properties of the tropopause as a result of human activity could have wide-ranging implications because of its physical and chemical roles in the climate system.”

This news brief appeared in the Random Data column of the Boston Globe’s Health/Science section on 8/05/2003.