An Ozone Rebound?

WASHINGTON, D.C.: The amount of ozone-depleting chemicals in the atmosphere fell for the first time in 1995, according to report to be published Friday in the journal Science. Ground-level measurements several sites worldwide reveal a very slight drop in the presence of chloroflurocarbons and other ozone-depleting atmospheric compounds containing chlorine and bromine. The ground-level decline could lead to a recovery of upper atmosphere ozone levels within a few years when the cleaner air has circulated into the stratosphere. TIME senior science writer Michael Lemonick says the trend is a direct result of international agreements like a 1987 Montreal protocol to curb the production of ozone-killer chemicals. "We first saw a decline in the production of these compounds. Now is the second stage, where we see a decline in the levels in the atmosphere." Lemonick says that chemicals currently present in the upper atmosphere will linger for years, and it remains to be seen if the slight drop can become a steep cut. "Reversing the trend of ozone depletion is like turning around a huge ocean liner," Lemonick says. "You can reverse the engines, but it still takes a while to change the ship's direction." If this trend is sustained, scientists say the Antarctic ozone hole, first detected in the 1980s, could begin to disappear in about 10 years. -->