The State Of The Ozone

The Not-So-Good and the Bad News About the Ozone

The world has received a continual stream of negative news about the ozone layer over the past five years. In August, 1994, UNEP issued its latest analysis of the state of the ozone layer (Scientific Assessment of Ozone Depletion: 1994), and for the shor t term, the only good news is that we have managed to slow down the rate of chlorine loading in the atmosphere.

According to UNEP, the rate of build up of "human-made compounds that deplete the ozone layer (e.g. chlorofluorocarbons (CFCs) and halons) have slowed in recent years as a direct result of reductions in global emissions of these compounds". 1 The downside of this good news is that there is still a positive build up of chlorine and bromine from industrial sources in the atmosphere.

The bad news from UNEP is that "record low global ozone levels were measured over the past two years..." and that the worst is yet to come around the year 1998 when the peak stratospheric chlorine and bromine abundances are expected to occur.2 "The ozone layer's most vulnerable period still lies ahead." 3

The Executive Director of the United Nations Environment Programme (UNEP), Ms Elizabeth Dowdeswell, prudently stated that: "While the 1994 Assessment Panel report confirms that we are heading in the right direction, we cannot afford to be complacent. The line that divides complacency from catastrophe is very thin and now is not the time to break that momentum." 4

If Only There Were No Volcanoes

The record low ozone levels over the past two years are attributed to the 1991 eruption of Mt. Pinatubo which "led to a large increase in sulfate aerosol in the lower stratosphere throughout the globe...[accelerating] the photochemical ozone loss associat ed with reactive hydrogen (HOx), chlorine, and bromine compounds in the lower stratosphere in mid latitudes and polar regions."5

The impact of Mt. Pinatubo's eruption upon the ozone layer, underscores the vulnerability of the Earth's protective shield and the necessity to immediately eliminate human sources of ozone destroying chemicals.

The UNEP Report warns "[If] there were to be a major volcanic eruption like that of Mt. Pinatubo or if an extremely cold and persistent Arctic winter were to occur, then the ozone losses and UV increases could be larger in individual years."6

Unusually Low Seasonal Ozone Ratings Over Antarctica Recorded

The UNEP report suggests that with the dust from Mt. Pinatubo having settled down the 1994 global ozone levels "are returning to values closer to those expected from the long-term downward trend..." 7 However there is always room for n asty surprises. The U.N. World Meteorological Organization (WMO) reported on August 16, ('94) that "the ozone level over Antarctica during February, March, and April was 10 percent lower than in the 'pre-ozone hole years,' a highly unusual phenomenon for the Antarctic summer.8

Ozone Depletion Caused by Humans Confirmed

Volcanic eruptions are clearly beyond human control, but the emission of ozone destroying substance is well within our purview. The UNEP Scientific Assessment confirms, yet again, "that the observed middle-and high-latitude ozone losses are largely due to anthropogenic chlorine and bromine compounds..."

Unfortunately, there is very little that we can do to "change the timing or the magnitude" of the amount of industrial chlorine and bromine that will reach the stratosphere around the turn of the century. Nor can we prevent the ensuing ozone losses. That damage is already done.

Humans Can Help Speed Up The Recovery of The Ozone Layer

However, the UNEP Report points out, "there are four approaches that would steepen the initial fall from peak halocarbon levels in the early decades of the next century" and speed up the eventual recovery of the ozone layer. These four approaches are: ( a) totally eliminating the emissions of methyl bromide from agricultural, structural, and industrial activities by the year 2001; (b) totally eliminating the emissions of HCFCs by the year 2004; (c) ensuring that "halons presently contained in existing equipment were never released to the atmosphere"; and (d) ensuring that "CFCs presently contained in existing equipment were never released to the atmosphere". 9

It is estimated, that these four measures combined, could speed up the decline of the industrial chlorine content of the stratosphere by up to 30% over the next 50 years, provided that there is full compliance to the Amendments and Adjustments to the Mon treal Protocol.

The UNEP report writes:" Based on assumed compliance with the amended Montreal Protocol (Copenhagen, 1992) by all nations, the stratospheric chlorine abundances will continue to grow from their current levels (3.6ppB) to a peak of about 3.8ppb) around the turn of the century....After around the turn of the century, the levels of stratospheric chlorine and bromine will begin a decrease that will continue into the 21st and 22nd centuries....Global ozone losses and the Antarctic ozone "hole" were first disce rnible in the late-1970s and are predicted to recover in about the year 2045, other things being equal."

From the Frying Pan Into the Fire: Global Warming

Unfortunately, the UNEP report also notes that "Many of the substitutes for CFCs and halons are also notable greenhouse gases..." but because they do not deplete the ozone they "fall under the purview of the Framework Convention on Climate Change. There is a wide range of values for the Global Warming Potentials (GWPs) of the HFCs (150-10,000)--about half of them having values comparable to the ozone-depleting compounds they replace...."10 Furthermore, as "the atmospheric growth ra te of several major ozone-depleting substances have slowed..." the atmospheric abundances of the CFC substitutes [e.g. HCFCs and HFCs] are increasing.

While the Montreal Protocol does not address the issue of global warming, the report does point out that "consideration of ozone change will be one necessary ingredient in understanding climate change..." [and] "changes in ozone since pre-industrial times as a result of human activity are believed to have been a significant influence on radiative forcing: this human influence is expected to continue into the foreseeable future."

Past Statements Regarding Ozone Depletion

April, 1991: U.S. NASA scientists announced that ozone destruction over the Northern hemisphere's mid latitudes including highly populated region such as the U.S. and Europe was two to three times as great as scientists had previously calculated. 11

April, 1991: The U.S. Environmental Agency (EPA) revised its skin cancer statistics, and projected that over the next fifty years 12 million Americans will contract skin cancer and 200,000 will die from malignant melanoma, as a result of increased UV -B radiation reaching the surface of the earth due to ozone depletion in the stratosphere. 12

July, 1991: British scientists reported that the ozone layer over Europe had depleted by as much as 8% during the past decade, a rate twice that of the previous decade. 13

October, 1991: The Scientific Assessment Panel of the United Nations Environment Programme (UNEP) announced that significant ozone destruction was now occurring over highly populated regions of both hemispheres in spring and summer, when the sun's ha rmful ultraviolet rays are the strongest and pose the greatest danger to human health, crops, wildlife and marine ecology. 14

In its October, 1991 report UNEP predicted that ozone depletion over mid-latitudes in the 1990s will be at least double those experienced in the 1980s. UNEP also concluded that the current stratospheric chlorine loading level of 3.6 parts per billion by volume (ppbv) will peak at about 4.1 ppbv at the turn of the century. 15

October 15, 1991: Dr. Joseph Farman, the British scientist who discovered the Antarctic ozone hole in 1985, warned that ozone loss over the UK and Northern Europe could reach as high as 30% by the year 2000. 16

November, 1991: UNEP published a report on the Environmental Effects of Ozone Depletion. The report states that the effects of increased UV-B radiation resulting from ozone depletion includes induction of immunosuppression in humans and substantial increases in cataract cases and blindness worldwide. 17 "A 1% decrease of ozone, other things being equal, would lead to between 100,000 and 150,000 additional cases of cataract-induced blindness world-wide." 18

December, 1991: The Scientific Assessment of Ozone Depletion, stated that "extensive ozone holes have been observed in four of the last five years over the Antarctic." The report also states that "it is important to recognize that the environmenta l impact of ozone loss, with corresponding enhancement of ultraviolet-B exposure, may be cumulative over the years with high ozone depletion. 19

February, 1992: NASA and European Scientists reported the highest ever stratospheric levels of chlorine monoxide (ClO), 1.5. ppbv over parts of the Northern Hemisphere. ClO is the reactive form of chlorine that triggers ozone loss. Scientists feared 1 to 2 percent daily ozone over some latitudes. 20

April 7, 1992: The European Arctic Stratospheric Ozone Experiment reported ozone depletions ranging from 10 to 18 % over various locations in Europe. The report concludes that "the potential for large ozone loss will increase with the higher chlorine amounts which are inevitable in the stratosphere later this year." 21

Dr. Michael Kurylo, NASA's Arctic ozone Project Manager, was quoted in the February 5, 1992 issue of The Guardian as saying: "Everyone should be alarmed about this...Even if CFCs were phased out at once, it would take until 2060 or 2070 to restore th e ozone layer to health - this legacy will be with us for a long time." 22

Delegates to the Open Ended Working Group of the Montreal Protocol (Geneva, April 6-15, 1992) were told by NASA's Dr. Bob Watson that beyond our current predictions there is "room for surprises with a chlorine regime that has become an unprecedented feature on the planet." 23 These surprises may come in the form of non-linear ozone depletions.

1992 models calculated ozone depletions with a chlorine and bromine loading up to 4.1 ppb. However, should chlorine and bromine loading exceed that level, scientists warned "that ozone losses may be more than linearly proportional to [such] increases, and depletions that were initially limited to the winter pole now [would] extend towards the equator." 24

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