UV The Antarctic ozone "hole" is unambiguously caused by anthropogenic emissions of halocarbons, and such emissions are strongly implicated in the observed depletion of the global ozone layer. These findings are drawn from extensive ground-based and satellite measurements, four major airborne campaigns, and the development and application of stratospheric models. This body of evidence underlies both domestic and international policy decisions, including the London (1990) and Copenhagen (1992) amendments to the Montreal Protocol and the U.S. Clean Air Act Amendments of 1990 to accelerate the phaseout of halocarbons.

Although there is a worldwide network of ozone monitoring stations, there is no analogous network for measuring the changes in ultraviolet (UV) radiation. There is particularly a need to monitor increases in UV-B radiation (radiation within the wavelength range most suspected to cause biological damage) that might be expected due to stratospheric ozone depletion. Collecting accurately calibrated, high-quality, spectrally-resolved UV data is both technically difficult and expensive. Although the U.S. and other nations are operating a number of UV monitoring sites, there are too few measurements currently available to verify predicted increases in surface UV radiation resulting from stratospheric ozone depletion other than in Antarctica, or to provide a comprehensive understanding of the effects of other change in the global system.

Beach image © 1993, Paul Grabhorn