Global Warming Cooling Shrinking Upper Atmosphere

The average density of the air in the region more than 60 miles up — just a trillionth of that near the surface — has dropped 10 percent over the last 36 years, and it could decline by a total of 50 percent by the end of the century, scientists at the Naval Research Laboratory in Washington report.

The link between carbon dioxide and high-altitude cooling is much clearer than the gas's link to warming near the surface, scientists said, because the highest atmospheric layer, barely more than a scattering of ions and molecules, sees no confounding influence from clouds, weather systems and oceans.