Ozone decline levelling off

A new global study involving long-term data from satellites and ground stations indicates Earth's ozone layer, while still severely depleted following decades of thinning from industrial chemicals in the atmosphere, is no longer in decline.

Betsy Weatherhead, a researcher with the Cooperative Institute for Research in Environmental Sciences, a joint institute of the University of Colorado at Boulder and the National Oceanic and Atmospheric Administration and corresponding author of the study, said the team documented a levelling off of declining ozone levels between 1996 and 2002, and even measured small increases in some regions.

"The observed changes may be evidence of ozone improvement in the atmosphere," said Weatherhead. "But we will have to continue to monitor ozone levels for years to come before we can be confident."

It most likely will be decades before the ozone layer recovers, and it may never stabilize at the levels measured prior to the mid-1970s, when scientists discovered human-produced chlorine and bromine compounds could destroy ozone and deplete the ozone layer, Weatherhead said.