Climate models also suggest that greenhouse gases such as carbon dioxide and methane may enhance the transport of water into the stratosphere. Though not fully understood, it seems the increased transport of water vapor to the stratosphere was probably induced by human activities. Shindell noted that his global climate model coincides with satellite observations of the world's stratospheric ozone levels when the water vapor factor is increased in the stratosphere over time. The impact on global warming occurs because both water vapor and ozone are greenhouse gases, which trap heat leaving the Earth . Increased water vapor in the stratosphere traps heat making it warmer on the ground, while the ozone loss makes it colder on the ground.
Water vapor has a highly greater effect, so that overall, the changes increase global warming.
Shindell stressed that although ozone depletion cools the Earth's surface, repairing stratospheric ozone is vital to block harmful ultraviolet radiation, and other greenhouse gas emissions need to be reduced. He also used 14 years of lower stratospheric measurements that show sizable increases in water vapor. Although some studies don't agree with lower stratospheric observations of water vapor trends, studies released since Shindell's paper was written, do agree with the increases he used, and indicate that they have been taking place for more than four decades already. Its mission includes improvement of understanding stratospheric ozone depletion by analyzing vertical profiles of ozone, hydrogen chloride, hydrogen fluoride, methane, water vapor, nitric oxide, nitrogen dioxide, and aerosols. Comet Exploration Past Weeks' News Archives - Archives of past weeks' Daily Selected News Stories.