Earth's upper atmosphere cooling dramatically

New research shows that the outermost layer of the atmosphere will lose 3 percent of its density over the coming decade, a sign of the far-reaching impacts of greenhouse gas emissions. As the density declines, orbiting satellites experience less drag.
© UCAR
When the sun is relatively inactive - as it has been in recent years - the outermost layer of Earth's atmosphere cools dramatically, new observations find.
The results could help scientists better understand the swelling and shrinking of our planet's atmosphere, a phenomenon that affects the orbits of satellites and space junk.
The data, from NASA's TIMED mission, show that Earth's thermosphere (the layer above 62 miles or 100 km above the Earth's surface) "responds quite dramatically to the effects of the 11-year solar cycle," Stan Solomon of the National Center for Atmospheric Research in Boulder, Colo., said here this week at the annual meeting of the American Geophysical Union.
Knowing just how the energy flowing out from the sun naturally impacts the state of the thermosphere also will help scientists test predictions that man's emissions of carbon dioxide should cool this layer. (While that may seem to contradict the idea of global warming, it has long been known that carbon dioxide causes warming in the lowest part of the atmosphere and cooling in the upper layers of the atmosphere.)
Earth's thermosphere is one of the least explored parts of the atmosphere, but it is important because "the thermosphere is where the sun first interacts with our atmosphere," said James Russell III of Hampton University in Hampton, Va.
http://news.mobile.msn.com/en-us/articles.aspx?afid=1&aid=34479085 Space.com 10:48 AM EST December 18, 2009