Nathan

Troubled Times: Shrinking Atmosphere: "But even after accounting for those fluctuations, Jarvis and his colleagues discovered that the thermosphere was in a long-term retreat. Compared with measurements from the late 1950s, the zone had 'shrunk' by about 5 miles - an indication that the thermosphere is cooling. What does this cooling and shrinking have to do with global warming? Plenty, Jarvis said. Cooling in the upper atmosphere is one of the widely predicted consequences of global warming. In computer simulations of the so-called greenhouse effect, carbon dioxide and other gases trap heat near the Earth's surface while causing the upper atmosphere to cool, and therefore contract. Jarvis called the finding 'not a shattering result, but another indicator that things are changing.' Earlier, less ambitious studies in Europe also detected a contraction in the thermosphere, while a report earlier this month by two Indian scientists was unable to confirm the trend. The British scientist stressed, though, that the five-mile drop in altitude 'is not in itself harmful to people.' 'It is however, another warning signal about what damage to the atmosphere can be caused by human impact,' he said. "