Ozone Layer Depletion
The ozone layer over the U.S. and worldwide has been found to be thinning, which is likely to have serious health and biological implications (1,5,11,15,21-23). The hole over Antartica is still growing and reached a high for this time of year in 2003(24,25). The 2003 Antarctic ozone hole was the second largest ever observed, say scientists from three U.S. federal agencies. Researchers from the National Oceanic and Atmospheric Administration (NOAA), the National Aeronautics and Space administration (NASA), and the Naval Research Laboratory made the observations. The seasonal ozone hole over Antarctica widened sharply in 2005, making
it the biggest hole since 2000 and the third largest on record, according to measurements reported here on Tuesday by the European Space Agency (ESA). . There has been a resulting increase of approx. 0.5% per year in ultraviolet radiation(UV) since the mid 1980s, with an even larger increase of approx. 2% in 1992 (2).
Ozone losses reached record levels in 1993, with the levels over Canada for the first 4 months about 11 to 17 % below normal(9). According to satellite measurements as confirmed by ground measurements throughout the eastern U.S., the ozone layer losses reached record levels in the northern hemisphere in 1994(12) again in 1995(7), and in 1999 and 2000(21,22). The ozone layer was 10% below normal over Europe in the winter of 1995, and 15% to 20% below normal over the U.S. in March 1995. The level was 35% below normal in some Arctic regions. Average ozone measurements in the northern hemisphere by NOAA for Dec 95 to March 96 were 10 to 25% lower than levels during the base period 1979-1986(19) and the lowest in history in March 1997. 20 to 25% reductions were seen in far northern regions of Greenland, Europe, and Siberia(19). The reduction over Alaska was approx. 10% and over the mainland U.S. was 6%. These record levels of ozone thinning result in corresponding increases in UV-B increases(11,13,21). The record low ozone levels over Antarctica in 1993, 1994, and produced increases in UV-B levels that were 44 % higher than in 1992 for one monitoring site(13). Recent years have again reached even lower levels and the worst hole on record in 2000(11,23). Since 2000 total chlorine is declining, while bromine from industrial halons is still increasing, albeit at a slower rate than was occurring previously(25).
Biologists indicate that the increased ultraviolet radiation due to ozone declines is already having significant adverse impacts on ocean plankton, coral reefs, and ocean food chains(11,16). UV-B inhibits growth of plants and accumulation of biomass, causing serious damage to crops, plants, trees, and plankton(9,10,16). Controlled studies have found that UV-B retards the growth of freshwater and ocean algae, and also of the larva and small animals that live on the larvae(10,16). The increased UV-B in the 1990s has caused failures in reseeding Canadian forests and significant decreases in seedling growth rate. The increased UV-B levels could also be a factor along with global warming in dramatic declines in plankton levels in recent years, such as the 80 % decline in zooplankton levels in the Pacific Ocean off the coast of California(18).
A 1% decrease in ozone in the atmosphere has been found to lead to an increase of over 2 % in UV-B(11,21), and a 2% to 4% increase in skin cancer and a 0.6 to 0.8% increase in cataracts. Studies have found UV radiation levels to be a major factor in causing skin cancer- being both a tumor initiator and tumor enhancer(11,15,21). The number of cases of the most serious type of skin cancer, melanoma, has risen by over 4% per year over the last decade, and incidence doubled in the U.S. between 1980 and 1994(4). Other types of skin cancer are also increasing(4). The northern hemisphere is seeing approx. 3 % reduction per decade in atmospheric ozone levels, resulting in a 2 to 3% increase per year in related skin cancer in Europe(21,22).
UV exposure also adversely affects the immune system, and has been documented to be related to immune system diseases and genetic or metabolic problems such as herpes simplex, tuberculosis, leprosy, lupus, etc. Higher doses of UVB appear to have even more widespread adverse effects on plants, animal, and ecosystems. Frogs and other amphibians are declining in numbers drastically all over the world, and scientists at Oregon State University and the Univ. of California at Santa Cruz have found increased levels of ultraviolet radiation B along with acidic water to be a major factor by damaging frog eggs(6). This is also resulting in increases in insect populations and drops in the number of frog-eating fish and wildlife. Forests have also been found to be adversely affected. UVB also damages polymers used in building materials, paints, packaging, etc(4).
The ozone layer has declined globally over 6 % since 1980, and even more over northern U.S. latitudes(1,11,21). Satellite measurements by Nimbus-7 in 1992, 1993, and 1994 show levels have reached record lows over much of the earth and declined much more rapidly in 1992 than ever before. The global decline in 1992 alone was over 2 % and perhaps was aided somewhat by aerosols from the Mt. Pinatubo eruption(1). An ozone hole has been found to be forming over the Arctic area similar to the one previously documented over Antarctica(11,21,22). The formation of polar statospheric clouds act as catalyst in ozone destroying chemical reactions in the stratoshpere, especially over Antarctica and the Arctic(11,21-23). While the formation of such clouds in the Arctic is not as heavy and consitent as in Antarctica, such formations are increasing and appear to be increased by global warming. Scientists have also found concentrations of ozone destroying chlorine monoxide over the U.S. to be much higher than previously expected. Chlorine compounds such as chlorofluorocarbons(CFCs) and other ozone layer destroyers such as nitrous oxide have been found to be rapidly increasing in the atmosphere in recent years. Space shuttle measurements of hydrogen chloride(Hcl) and hydrogen fluoride(HF) levels in the upper stratosphere found an increase in concentration of 37% and 62% respectively between 1985 and 1992(14). The program also determined that the main source of the increases in ozone destroying chemicals in the stratosphere appears to be man-made sources such as CFCs, HCFCs, and halons. HF levels were growing at exponential rates of over 5% per year. NASA has found natural chlorine to account for only 20% of the chlorine effect on ozone in the stratosphere, while virtually all fluorine, which is even more harmful to ozone, is from manmade sources(11). Another destroyer of ozone in the stratosphere for which manmade emissions from power plants, high flying aircraft, and other sources are increasing is nitrous oxide(N2O). Power plant combustion at lower temperatures to reduce overall levels of nitrogen oxides can produce higher levels of nitrous oxide. Conversion of tropical forests to farm or ranch land can reduce CO2 sequestration while increasing nitrous oxide emissions by as much as a factor of 3 (11,17).
This decline could have large effects on Florida's sun based tourist businesses, as well as on increased health costs and crop losses(3). Florida tourism is a multibillion dollar industry, and insurance cost of skin cancer treatment are already rapidly increasing. A Florida Dept. of Commerce official indicated that there appears to have been a significant decline in beach tourism in the last 5 years due to ultraviolet skin damage concerns. Tourist related sales in beach areas amount to over $10 billion per year, not counting large amounts of uncounted real estate business, so even a decline of 1% would result in reduced tourism spending in the hundreds of millions of dollars.
Air conditioning and refrigeration systems are a major user of CFCs, and some types of units will be both less efficient and more expensive in the future due to limits or bans on the use of CFCs. New cooling technologies that do not use CFCs such as natural gas chillers, natural gas heat pumps, heat pipe cooling systems, and desiccant cooling systems appear to be cost effective for many applications and are likely to expand their share of the cooling market(8).
New technologies for refrigeration that are much more efficient than conventional compressors are also being developed. HFCs, which are being used in some cases to replace CFCs because of their lesser effect on the ozone layer, have been found to have an average of about 30 times as much greenhouse gas effect as CO2.
Countries reached an agreement in 1987 to phase out CFCs over the next 10 to 15 years(26). The decline of the ozone layer has been stabilized since 2005 at a little over 3% less than the 1964-1980 average, and the magnitude of the loss is no longer increasing. According to new studies(27) based on monitoring data,the winter ozone hole is expected to gradually decline and repair over the next 60 years. The hole in the Earth's ozone layer has shielded Antarctica from the worst effects of global warming until now, according to the most comprehensive review to date of the state of the Antarctic climate. But scientists warned that as the hole closes up in the next few decades, temperatures on the continent could rise by around 3C on average, with melting ice contributing to a global sea-level increases of up to 1.4m. The western Antarctic peninsula has seen rapid ice loss as the world has warmed, but other parts of the continent have paradoxically been cooling, with a 10% increase in ice in the seas around the region in recent decades. Many climate change sceptics have used the Antarctic cooling as evidence against global warming.
But John Turner of the British Antarctic Survey said scientists are now "very confident" that the anomaly had caused by the ozone hole above Antarctica. "We knew that, when we took away this blanket of ozone, we would have more ultra-violet radiation. But we didn't realise the extent to which it would change the atmospheric circulation of the Antarctic."
These changes in weather have increased winds in the Southern Ocean region and meant that a large part of the continent has remained relatively cool compared with the western peninsula. But because the the CFC gasses that caused the ozone hole now been banned, scientists expect the damage to repair itself within the next 50-60 years. By then the cooling effect will have faded out and Turner said the Antarctic would face the full effects of global warming. This means an increase in average air temperatures of around 3C and a reduction in sea ice by around a third.
The biggest threat to the continent comes from warming seas. Robert Binschadler, a glaciologist at Nasa who monitors Antarctic ice sheets, said: "The heat in the ocean is getting underneath the floating ice shelves, these floating fringes of the ice sheet that are hundreds of metres thick. That warm water is melting the underside of the ice shelf, reducing the buttressing effect." Thinning of the ice shelf at the fringes leads to glaciers moving more quickly. Average sea-level rise will be closer to 1.4m by the end of the century- more than the IPCC estimate which not take changes in the ozone layer over Antarctica into effect.
(1) J.F. Gleason et al, N.A.S.A., "Record Low Global Ozone in 1992", Science, April 23, 1993 & Science News, April 24, 1993
& "NASA identifies cause of ozone depletion", Science News, Vol 146, p422. & J.R. Herman et al, N.A.S.A., "Ozone Depletion at Northern and Southern Latitudes- 1979 to 1991", Journal of Geophysical Research, Vol 98, No. D7, July 20, 1993, pages 12783-12793.
(2) Kerr et al, Science, Vol 262, 1993, p1022 & T. Eck et al, Geophysical Research Letters, Feb/Mar 1995 & National Aeronautics and Space Administration & National Oceanic and Atmospheric Administration, in Florida Times Union, page B1, 12-27-92.
(3) U.S. EPA, in Science News, 1988.
(4)Science News, 1-22-94, p54 and Vol 151,6-21-97,p383; & The Miami Herald, "Lifetime Skin Cancer Risk Projected to Hit 1 in 75", June 3,1991.
(5) J.Herman et al, NASA Goddard Space Flight Center, Journal of Geophysical Research, Volume 98, 1993, p12738 & J.of Geophysical R., Vol 99, 1994, p3483 & Science News, April 13,1991 & Science News, Vol 139 & Science News, Volume 138, p198 and p228, & Science, Volume 252, p204.
(6) Dr. Andrew Blaustein et al, Oregon State Univ., "The Puzzle of Declining Amphibian Populations", Scientific American, April 1995, p52-56 & Univ. of California at Santa Cruz(408-459-2495), the Furturist, May 1996, p7.
(7) National Oceanic and Atmospheric Administration, Science News, Vol 147, 5-6-95, p277.
(8) Gas Research Institute, Gas IRP Review, July/August 1995.
(9) Dr. J. Kerr, Director: Canadian Ozone Research Program & Dr. B. Worrest, U.S. EPA Ozone and Global Exchange Program Head, International Conference on Ozone Depletion and Ultraviolet Impacts, Whistler, B.C., 1993.
(10) M.L. Bothwell et al, Canadian National Hydrology Research Institute,
Science, July 1, 1995.
(11) Subcommittee on Global Change Research, National Science and Technology Council, Our Changing World, 1995.(Report to Congress); & NASA, in News on Earth, July 1998.
(12) NOAA Climate Analysis Center, U.S. Monthly Climate Summary, Weekly Climate Bulletin, Vol 94, p5, Nov 1994.
(13) World Meteorological Organization Global Ozone Research and Monitoring Report 37, Geneva, Switzerland, 1995 & Science News, Vol 148, p245.
(14) M.R. Gunson et al, Geophysical Research Letters, Vol 21, p2223-2226, 1994. (15) A. Ziegler et al, Nature, Vol 372, p773-777, 1994.
(16) D. Hodgson et al, Nature, Vol 370, p 547-549, 1994.
(17) Reesburgh et al, Global Atmosphere-Biosphere Chemistry, 1995.
(18) J.McGowan et al, Science, Vol 267, p1324-1326, 1995.
(19) National Oceanic and Atmospheric Administration, Northern Hemispehre Winter Summary, in Clean Air Compliance Review, April 22, 1996.
(20) P.K. Bhartia, NASA Goddard Space Center, Science News, Vol 151, 5-10-97.
(21) P. Simon, Director, Belgium Institute of Space Aeronomy, & J. Pommereau, Director of Research, Centre National de la Recherche Scientifque(France), Sept 2000
(22) European Space Agency, Press Release, Dec 3, 1999; & E. Jensen, National Aeronautics and Space Administration(NASA), Ames Research Centre, May, 31, 2000; & O.Toon, Univ. Of Colorado,
(23) M Proffit, U.N., World Meteorological Organization(Switzerland, Oct 10, 2000); & National Aeuronautics and Space Administration, Press Release, Sept 8, 2000; & L.Amarales, Chilean Health Minister; & D. Casiccia, Dept Head, Univ. of Magallanes;
(24) straight to the source: Australian Broadcasting Corp., Reuters, 13 Sep 2003<www.gristmagazine.com/forward.pl?forward_id=1498>
(25) Bryan Johnson
of NOAA's Climate Monitoring and Diagnostics Laboratory.
2004 & NOAA Scientific Assessment of Ozone Depletion: 2002, http://esrl.noaa.gov/csd/assessments/2002/
(26) CFC Phaseout Agreement, Montreal Protocol ,1987