They are used in refrigeration. He proposed that the deadlines for the cessation of the use of CFCs be advanced by a decade. The global agreement was to phase out CFCs among industrialized countries by 2030 and among developing countries by 2040. It was also later discovered that HCFCs warm up the earth a lot faster than carbon dioxide (Lean). HCFCs were first assumed to be beneficial alternatives to CFCs (Baker 2000). These chemicals were found to be potent greenhouse gases, which heat up the earth up to 4,000 times more than carbon dioxide (Lean). The Montreal Protocol was successful in immediately phasing out ozone-depleting chemicals, such as CFCs, by replacing them with less damaging alternatives (Sengupta 2005). Manufacturers of fire extinguishers and refrigerators could be commended for their response. But the real effects of that response will not be evident until after many years, as CFCs remain in the atmosphere for long periods. These chemicals create the greatest damage in the Antarctic region because of its unusual weather. High-altitude clouds form best at those levels and thus enhance the conditions and reactions, which destroy the ozone layer. The weather influences changes in the size of the hole from one year to another. It first appeared to be shrinking at the start. But in 2003, it grew to a record size. Then it grew smaller, an indication of rapid repair. Despite this trend, Jonathan Shanklin of the British Antarctic Survey said that hole would not disappear completely until the middle of the century, at the earliest (Sengupta).

The analysis of the first and second Stratospheric Aerosol and Gas Experiment or SAGE and the Halogen Occultation Experiment or HALOE offered evidence for the first stage of ozone layer recovery (Steitz 2003). In 1997, scientists found less ozone depletion in the upper stratosphere at 22-28 miles altitude. The decrease was consistent with the reduction of man-made chorine and bromine-containing chemicals. These changes were documented by satellite, balloon, aircraft and ground-based measurements. Associate Professor Mike Newchurch of the University of Alabama and lead scientist in the SAGE II-HALOE study said that total ozone recovery would take decades. More information was needed, such as the effect of climate change on ozone recovery. SAGE I was launched in 1979 on the Applications Explorer Mission B. spacecraft. SAGE II was launches in 1984 on the Earth Radiation Budget Satellite. HALOE was carried by the Space Shuttle Discovery on the Upper Atmosphere Research Satellite in 1991. The research was funded by the National Aeronautics and Space Administration's Science Enterprise in order to better understand and protect the earth. Ozone depletion not only allows the sun's ultraviolet rays into the earth and threatens health and life. It also causes the ozone hole over Antarctica every spring (Steitz).

Policies in Reducing Ozone Depletion and Forecast

Measurements provided by the three satellites and three ground stations confirmed the slowing down of ozone depletion in the past decade (Connor 2003). But Professor Newchurch emphasized that it would take at least half a century before the ozone layer could completely repaired. He and fellow scientists acknowledged the success to the Montreal initiative of 1987 to phase out the production of CFCs in products, such as aerosol sprays and refrigerators. It is the chlorine content in CFCs, which destroys the ozone layer. He said that ozone depletion was declining at roughly 8% per decade. At that time, the depletion was only at about 4% per decade (Connor).

Despite the first indication of recovery, Professor Newchurch stressed that ozone-depleting chemicals should be produced again (Connor 2003). The harmful ultraviolet light produced by the sun is naturally destroyed in the absence of pollution. But the chlorine in CFCs is far more destructive than pollution alone. It is responsible for large-scale ozone destruction in the polar regions at the end of winters when sunshine induces photochemical reactions (Connor).

California Congressman Richard Pombo introduced the Methyl Bromide Fairness Fact (Baker 2000). It focused wide-scale attention on methyl bromide, a toxic and ozone-depleting chemical used primarily by California strawberry and Florida tomato farmers. The Act would postpone U.S. phase-out deadline to 2015. This was the deadline for developing countries to stop producing and consuming the chemical. It is already banned in many countries, including the Netherlands and Canada. Methyl bromide has been linked to almost 500 cases of poisoning since 1982 in California. Of this number, 19 were fatal. The government and the scientific community agree that the use of methyl bromide compounds should be regulated. The EPA categorizes methyl bromide as a Class I ozone-depleting chemical, scheduled for phase-out by the Clean Air Ac. The United Nations Environment Programme said that the phase-out of CFCs and the removal of methyl bromide emissions from industries...

Bill Thomas of the EPA's Stratospheric Protection Division commented about farmers' reluctance in changing their crop rotation systems. These have been developed around methyl bromide. But there are effective substitutes, which would allow them to continue crop production in ways they have been used to (Baker).
Professor Newchurch recommended the continuing adherence to the Montreal Protocol in the collective effort at fully regenerating the ozone layer (Chafe 2003). Stepher Montzka of the National Oceanic and Atmospheric Administration and lead author of the study on methyl bromine sustained Professor Newchurch's suggestion. He said that the Protocol was quite important in the overall initiative. He pointed to decreases in measured ozone-depleting substances as the direct result of international limits placed on the production of these substances. Continued and worldwide observance of these restrictions, as set out in the Protocol, could either slow or delay ozone recovery. and, indeed, a day after the release of the study on bromine, New York Times reported that the Bush Administration sought to exempt methyl bromide from the Protocol's list of banned substances. Strawberry farmers and golf course owners argued that the pesticide had no inexpensive substitutes (Chafe).

California Institute of Technology researchers predicted that the accumulation of hydrogen gas could indirectly decrease atmospheric ozone by 10% ((Tindol 2003). Hydrogen gas can leak from pipelines and storage tanks. Findings of the research showed that 60-120 trillion grams of hydrogen would be released into the atmosphere every year if used to replace fossil fuel entirely. Doing so would double or triple the hydrogen content in the atmosphere from all natural and human sources. Molecular hydrogen easily and freely mixes with the stratospheric air. This puts in more water at high altitudes and increases dampening of the stratosphere. These conditions will cool the lower stratosphere and disturb the ozone chemistry (Tindol).

The researchers said the effects of hydrogen gas on the atmosphere remained uncertain on account of limited knowledge and understanding of the hydrogen cycle (Tindol 2003). Assistant geochemistry Professor John Eiler said that the impact of hydrogen gas would depend largely on the earth's ability to take in "anthropogenic hydrogen." This man-made gas will either be absorbed in the soil or react with other substances in the atmosphere. The impact would be minimal if the soil absorbs it. But if let out in the atmosphere, it would most likely cool the stratosphere and destroy the ozone layer (Tindol).

Conclusion

The life-protecting ozone layer in the stratosphere has been damaged by substances, primarily CFCs and methyl bromide. The discovery of a gaping hole over the Arctic region in the 80s confirmed the occurrence of ozone depletion. Consequences could include increased incidence in skin cancers and disturbed plant functions. The Montreal Protocol was immediately signed by 173 concerned nations. It set a schedule for the phase-out of the chemicals from manufacturing and use.

Ozone levels over the Arctic region fell at 40% lower than normal, creating fear that an ozone hole could form over Britain, North America and Russia. But all sorts of obstacles lie on the path of an immediate, entire and effective implementation of Protocol goals. Industrialized nations have an earlier phase-out timetable than developing nations. There are also local violations to contend with. A 1997 SAGE II - HALOE study provided evidence of initial ozone recovery but it was limited to a particular portion of the atmosphere. Scientists recommend faithful adherence to the intents of the Montreal Protocol in eliminating the manufacture and use of all ozone-depleting substances in the earliest possible time. Even faithful adherence is unlikely to see total ozone recovery until half of this century in the earliest, according to scientists.

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