U.N. Agency Says Ozone Depletion Running at Record Levels
GENEVA (AP) _ A combination of manmade chemicals and volcanic gases caused unprecedented destruction of the protective ozone layer over large parts of the globe the past year, a U.N. environment agency said Friday.
The World Meteorological Organization said ozone levels over northern Europe, Russia and Canada last winter and spring were 12 percent below the seasonal average, ″an occurrence never before observed in more than 35 years of continuous ozone observations.″
″Statistically one could expect such low values only once in 100 years,″ said Dr. Rumen Bojkov, a weather expert with the organization.
The Geneva-based agency also reported worryingly high depletion rates for ozone over the South Pole and southern Argentina and Chile.
The ozone layer shields the Earth against the sun’s damaging rays. Its depletion has been tied to increased incidences of skin cancer and vulnerability to disease and blindness. Its depletion has also been linked to reduced crop yields and damage to marine food chains.
When evidence of ozone depletion emerged in the 1970s, it was concentrated over the Antarctic during its spring period of September and October. However, scientists are increasingly reporting significant ozone decreases all year round and in all latitudes except the tropics.
The meteorological organization released its latest findings on the eve of a U.N.-sponsored meeting aimed at agreeing to faster targets for phasing out ozone-consuming chemicals.
The conference opens Tuesday in Copenhagen, Denmark, and ends with a ministerial session Nov. 23-25. It is expected to ban chlorofluorocarbons, or CFCs, by the start of 1996 - five years earlier than originally planned. CFCs are used in refrigeration, air conditioners and aerosols.
However, there is more controversy over phaseout targets for other substances like hydrofluorocarbons, developed as an alternative to CFCs but now also said to destroy ozone, and methyl bromide, used as a pesticide and fumigant.
″Implementing these decisions is a matter of urgency since our observations have proven that we are indeed running out of time,″ said Godwin Obasi, head of the meteorlogical group.
The report was based on data from 140 ground stations and satellites.
It said that ozone amounts over most of the northern hemisphere were ″exceptionally low compared to long-term averages″ during last winter and spring.
Average values in January were 20 percent below normal over northern Europe and down 16 percent over Canada. They were 15 percent below normal over Russia in February and March, it said.
Over the South Pole, ozone destruction of up to 65 percent was reported in the second half of September and early October. For nearly four weeks ozone sounding stations in Antarctica reported their lowest-ever daily values, it said.
″Scientists also observed that for a few days in early October permanently inhabited areas of southern Argentina and southern Chile were covered with an ozone layer containing only 50 percent of normal ozone amounts,″ it said.
The group said the situation was likely caused by a combination of manmade chlorine and bromine components reacting with lower-than-normal temperatures in the Antarctic. That combined with stratospheric aerosols from last year’s volcanic eruptions of Mount Hudson in Chile and Mount Pinatubo in the Philippines to produce chemical reactions that speed ozone destruction.
The group said that during the past three weeks the Antarctic ozone hole had been slowly filling and the worst of this year’s depletion was over.