Stratospheric Water Vapor is a Global Warming Wild Card

A 10 percent drop in water vapor ten miles above Earth

Observations from satellites and balloons show that stratospheric water vapor has had its ups and downs lately, increasing in the 1980s and 1990s, and then dropping after 2000. The authors show that these changes occurred precisely in a narrow altitude region of the stratosphere where they would have the biggest effects on climate.

Water vapor is a highly variable gas and has long been recognized as an important player in the cocktail of greenhouse gases — carbon dioxide, methane, halocarbons, nitrous oxide, and others — that affect climate.

Physorg