Global Ozone Layer Still in Danger Despite Slight Improvements in Northern Hemisphere since 1990s

The Japan Meteorological Agency released the "Annual Report of Ozone Layer Monitoring: 2005" on April 28, 2006, a summary of ozone trends over Japan and the Earth in 2005. Analysis of long-term trends of the ozone layer revealed that depletion of the stratospheric ozone layer, which peaked during the 1980s, is still occurring globally except at low-latitudes.

The average total ozone amount from 1990 to 2005 decreased by 4 percent over the entire Earth (4.8 percent in the southern hemisphere and 3.3 percent in the northern hemisphere), when compared to the data from before the 1980s. The total ozone values in the northern hemisphere alone have been almost constant or slightly increasing since the 1990s. In Japan, total ozone levels dropped dramatically during the 1980s, but have remained fairly constant or even improved slightly since the mid-1990s.

According to observational data from 2005, the average monthly total ozone over the latitude range of 60 degrees north to 60 degrees south was often lower than the mean total ozone by TOMS (Total Ozone Mapping Spectrometer) for the period between 1979 and 1992. In addition, the Antarctic ozone hole begun to expand earlier than usual, which is believed to have resulted from an extended stratospheric cooling below minus 78 degrees Celsius, temperatures that accelerate ozone destruction.

The Meteorological Agency projects that even if the full compliance to the Montreal Protocol on Substances That Deplete the Ozone Layer is achieved, the ozone layer will still be susceptible to depletion over the next 10 years or so. Furthermore, some studies indicate that the leakage of chlorofluorocarbon (CFC) gases and other ozone depleting substances from existing products will delay the recovery of the ozone layer, suggesting the need for careful monitoring on ozone layer changes.

http://www.jma.go.jp/jma/indexe.html

Posted: 2006/07/22 10:17:50 AM
Japanese version