CFC Destruction of Ozone - Major Cause of Recent Global Warming!
There has been a lot of discussion about global warming. Some say anthropogenic carbon dioxide (CO2) emissions caused the earth to warm. Others say there is no abnormality at all, that it is just natural warming. As you will see from the data presented and analyzed, a greater than normal warming did occur in recent times but no measurements confirm an increase in CO2 emissions, whether anthropogenic or natural, had any effect on global temperatures. There is however, strong evidence that anthropogenic emissions of chlorofluorocarbons (CFCs) were the major cause of the near recent abnormal warming.
CFCs have created both unnatural atmospheric cooling and warming based on these facts:
- CFCs destroyed ozone in the lower stratosphere-upper troposphere causing these zones in the atmosphere to cool 1.37 oC from 1966 to 1998. This time span was selected to eliminate the effect of the natural solar irradiance (cooling-warming) cycle effect on the earth's temperature.
- The loss of ozone allowed more UV light to pass through the stratosphere at a sufficient rate to warm the lower troposphere plus 10" of the earth by 0.48 oC (1966 to 1998).
- Mass and energy balances show that the energy that was absorbed in the lower stratosphere- upper troposphere hit the lower troposphere-earth at a sustainable level of 1.71 x 1018 Btu more in 1998 than it did in 1966.
- Greater ozone depletion in the Polar Regions caused these areas to warm up some two and one-half (2 ½) times that of the average earth temperature (1.2 oC vs. 0.48 oC) rise. This has caused permafrost to melt, which is releasing copious quantities of methane, estimated at 100 times that of manmade CO2 release, to the atmosphere. Methane in the atmosphere slowly converts to CO2 and water vapor and its release has contributed to higher atmospheric CO2 concentrations.
- There is a temperature anomaly in Antarctica. The Signey Island landmass further north, warmed like the rest of the Polar Regions; but south at Vostok, there has been a cooling effect. Although the cooling at Vostok needs to be analyzed in more detail, because of the large ozone hole there, black body radiation from Vostok (some 11,400 feet above sea level) to outer space is most likely the cause. Especially, since this phenomenon occurred over the same period that stratospheric ozone destruction took place.
Recent empirical data (1) show that atmospheric CO2 concentrations have no discernible effect on global temperature, see Figure 1. The temperature plots shown are from two sources; the National Aeronautics and Space Administration's (NASA) Microwave Sounding Unit (MSU) and the United Kingdom's (UK) Hadley Climate Research Unit. The CO2 plot is from the Mauna Loa Observatory in Hawaii. A certified meteorologist developed the temperature -- CO2 concentration graph from the data sources.
While CO2 levels increased some 20 ppmv over the past 10 years, global temperatures did not increase as predicted by the IPCC models -- they fell! The earth's temperature from 1998 to 2008 dropped by 0.7 to 0.8 oC depending on which temperature set is chosen for comparison.
Besides a carbon dioxide increase in the atmosphere, concentration of methane has increased 2.5 times from pre-industrial time (700 ppbv) to 1,745 ppbv in 1998 (2). In 2000, methane concentrations leveled off at 1755 ppbv and currently are slowly dropping. Two years earlier, stratospheric CFC concentrations leveled off and started to drop slowly, so methane emissions look like they are tied to depletion of ozone. Where is the methane coming from? A recent study (3) showed that the permafrost is melting in North Siberia and is releasing methane from the surface of thawing lakes that has been sequestered there since the Pleistocene era (10,000 to one million years ago). Further, the researchers' estimate that methane carbon is being emitted at a rate some 100 times the rate of carbon dioxide released from the burning of fossil fuels. Methane (CH4) slowly converts to CO2 in the atmosphere and this is the most likely cause for increased CO2 concentrations in the atmosphere.
Ozone Loss Effect
Stratospheric ozone has been diminished by CFCs and other refrigerants-propellants released into the atmosphere. These compounds are broken down by the sun's UV rays and release chlorine and bromine molecules that destroy the ozone. Scientists estimate that one chlorine atom can destroy 100,000 ozone molecules over its life in the stratosphere. With less ozone in the stratosphere, more UV rays hit earth, warming it up and increasing the risk of skin cancer. The protective ozone layer extends from 8 km (upper troposphere) up throughout the whole stratosphere.
The annual mean stratospheric ozone concentration above Antarctica (4) as measured at the British Antarctic Survey Station in Halley Bay (Latitude 76 south, Longitude 26 west) was 319 Dobson Units (standard measurement of ozone concentration) in 1956. In 1995, the mean value was 212 Dobson Units, showing an average drop of 33% from 1966. Although not as severe, ozone concentrations, north of the Arctic Circle, have dropped as well.
It is well known that the warming of the stratosphere is caused by the reaction of ultraviolet light with ozone. Energy is absorbed and ozone (O3) converts to diatomic (O2) and (O) nascent oxygen. Conversely, ozone loss decreases the amount of UV light absorbed and thus causes the stratosphere to cool. The direct effect of ozone concentration on temperature is shown in Figure 2 (5). Excluding the volcanic eruptions of El Chichon, Pinatuba, and others, whenever stratospheric ozone concentration drops, the temperature drops with it and vice versa. This effect is shown clearly from 1995 to 2005.
The legendary hypotheses (6) of Paul Crutzen, Sherwood Rowland, and Mario Molina led to CFCs being banned because they were destroying stratospheric ozone. In 1978, the USA banned the use of CFCs in hair sprays and other aerosols. Then in 1987, the world governments, through the United Nations Environment Programme (UNEP), agreed to limit the production and release of a variety of CFCs at a meeting in Montreal, Canada. Since then the agreement has become known as the Montreal Protocol. CFC production was stopped in developed countries but not in developing countries. It will be produced in China, Mexico and other developing countries until 2010.
CFC's and CCl4 are nearly inert in the troposphere and have lifetimes of 50-200+ years. Total stratospheric organic chlorine is currently a little over 3 ppbv. It is different in the stratosphere; the major source of CFC decomposition there is photolysis (7) reaction with ultraviolet (UV) light radiation. Ultraviolet light has wavelengths in the 200-400 nanometer (nm) range.
UV-A light is a low energy light and only about 5% of the UV-A light is absorbed by ozone. Most reaches the surface of the Earth. UV-B light is of moderate energy and ozone absorbs most of the UV-B light before it reaches the surface of the Earth. UV-C light is a high energy UV light. Both ozone and oxygen molecules absorb the UV-C light before it can reach the Earth's surface. Therefore, when there is low stratospheric ozone, more UV (A, B & C) light from the sun passes through the atmosphere to hit earth and heat it up.
CFC chlorine can take other reaction paths, but this is believed to be the predominant ozone destruction cycle. Though the concentration of CFCs is only around 3 ppbv in the stratosphere, one chlorine atom can destroy some 100,000 ozone molecules during its lifetime there. Since the 1960's the stratosphere has cooled (8), see Figure 3. The data suggest that the cooling is due to a loss of ozone.
When CFC refrigerants started to be produced and released into the atmosphere in the sixties, the stratosphere started to cool. The exceptions to cooling occurred during the times of the major volcanic eruptions of Agung, El Chichon and Mt. Pinatubo.
In 1998, the stratosphere was 1.37 oC cooler than it was in 1966. This 1966 to 1998 time span was chosen for analysis to negate the solar irradiance cycle and large volcanic eruption effects. The increase in stratospheric temperature from major volcanic eruptions lasts only two to three years; then the temperature goes back to where it would have been if there were no eruptions. As the lower stratosphere and upper troposphere cooled (1966 to 1998), the troposphere and earth warmed (9) by 0.48 oC see Figure 4.
In the Arctic, from 1966 to 1998 (10), the surface temperature increased 2 ½ times the average global temperature (1.2 oC vs. 0.48 oC), see Figure 5. The much colder than normal stratospheric temperatures cause even a greater loss of ozone and thus make the Polar Region stratospheres even cooler. This is why polar landmasses have warmed more than the rest of the earth. Ice crystals that form provide a surface for chemical reactions that change chlorine compounds that do not react with ozone (e.g. hydrogen chloride) into more active forms that do:
The change in ozone depletion chemicals in the stratosphere versus time (11), including future concentration projections is shown in Figure 6. Because of the Montreal Protocol implementation, CFC concentrations peaked in the late nineties and then started dropping slightly.
The line at 2 ppb corresponds to the time when ozone depletion was first detected (1980). It also shows when major ozone recovery is anticipated (2050 to 2060). Figure 7 shows a correlation of CFC concentration and average stratosphere and earth temperature plotted versus time.
The author plotted this graph based on data from Figures 4, 5 and 6. As shown by the vertical lines, in a logical sequence, CFC concentration started to drop first causing a reduction in stratospheric cooling and then a reduction in earth warming. When one sees like trends, it is a good indication that the trends are related to one another.
Large solar heating-cooling cycle variations occur every 80,000 to 110,000 years, but the sun's thermostat also changes in shorter term cooling-warming cycles of approximately 11 years (12), see Figure 9. The period chosen for analysis to negate this effect as mentioned previously was from 1966 to 1998. At these two points in time, the solar irradiance hitting the earth was approximately the same (1368.8 W/m2).
According to NASA (13), the lower stratosphere and upper troposphere, both of which have cooled together, extends from 19 km down to 8 km above the surface of the earth with the lower troposphere being in the 0 to 8 km elevation. Knowing how much the lower stratosphere-upper troposphere cooled and how much the lower troposphere-earth warmed, mass and energy balances could be made to determine how much more radiant energy hit the earth in 1998 compared to 1966.
Table 1 show mass and energy balances for the lower stratosphere-upper troposphere (19 km down to 8 km above sea level). The balances were made by first calculating the mass of gas in the lower stratosphere-upper troposphere. Then the recorded average temperature for the lower stratosphere-upper troposphere for 1966 and 1998 was used. The lower stratosphere-upper troposphere was 1.37 oC cooler in 1998 than it was in 1966. By subtracting the energy in the lower stratosphere-upper troposphere found in 1966 from that found in 1998 the loss in UV light energy absorption could be calculated. The amount of stratospheric heating from UV-B light in 1998 was 1.7123 x 1018 Btu less than it was in 1966.
The mass and energy balance in Table 2 shows the effect of that additional energy being absorbed by the troposphere/earth in 1998 compared to 1966. The lower troposphere temperature in 1966 (484oR) was used as a base and the added UV light (1.7123 x 1018 Btu) energy passing through the lower stratosphere/upper troposphere was added to the earth/troposphere. Using that increase in UV light energy, after heating the lower troposphere up by 0.48o C there was enough energy left over to heat up ten inches of earth plus water by 0.48 oC. This matches the recorded earth temperature rise from 1966 to 1998.
Added UV light hitting earth accounts for observed warming from 1966 to 1998 (0.48 oC or 0.863 oR)
Many factors influence the earth's temperature. From a scientific analysis, the effect of CO2 is very minimal as shown by an earth temperature drop of around 0.7 to 0.8 oC from 1998 to 2008 during a period when CO2 concentration in the atmosphere increased some 20 ppmv. It should be obvious to anyone analyzing climate change that climate-driving forces, other than CO2 control the earth's temperature. Chlorofluorocarbon destruction of stratospheric ozone correlates nicely with both the stratosphere cooling and earth warming anomalies seen over the time span from 1966 to 1998. CFCs appear to be the dominant cause of greater than normal earth warming. One can account for most, if not all of the 0.48oC rise in earth's temperature from 1966 to 1998 with the additional UV light that hit the earth due to loss of ozone in the stratosphere.
(1) D'Aleo, J. S., "Correlation Last Decade and This Century CO2 and Global Temperatures Not There"
http://icecap.us/images/uploads/Correlation_Last_Decade.pdf Data used to develop graph:
NASA microwave sounding unit for temperature of lower troposphere:
Hadley Met Centre for the temperature of the land and oceans:
and Scripps monthly CO2 concentrations from the Mauna Lao, Hawaii Observatory:
(2) Houghton, J.T., et. al.,"Climate Change 2001: The Scientific Basis Contribution of Working Group I to the
Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), Cambridge University
Press, UK, pp 944, 2001.
(3) Walter, K.M., et al. "Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming",
Nature 443, 71-75, Sept. 7, 2006.
(4) Halley Bay ozone data taken by the British Antarctic Survey,
(5) United Nations Environmental Programme (UNEP) Vital Ozone Graphics, p. 13, ISBN 978-92-807-2814-9
(6) Nobel Prize in Chemistry, The Royal Swedish Academy of Sciences, October 11, 1995.
(7) Zander, R. et. al., "The 1985 chlorine and fluorine inventories in the stratosphere based on ATMOS
Observations at 30 degrees North latitude", J. Atmos. Chem. 15, 171, 1992.
(8) HadAT2 radiosonde developed by the United Kingdom Met Office Hadley Centre, maintained by Peter Thorne
and Holly Titchner. http://hadobs.metoffice.com/hadat/images.html. Hosted by Met Office Hadley Centre for
(9) Brohan, P., et.al. 2006: Uncertainty estimates in regional and global observed temperature changes: a new
dataset from 1850, J. Geophysical Research 111, D12106, doi: 10.1029/2005JD006548
(10) "Impacts of a Warming Arctic: Arctic Climate Impact Assessment, ACIA Overview Report", Cambridge
University Press, 2004
(11) "Australia State of the Environment 2001 Independent Report to the Commonwealth Minister for the
Environment and Heritage, p. 27.
(12) Lean, J. 2000, Evolution of the Sun's Spectral Irradiance Since the Maunder minimum. Geophysical Research
Letters, Vol. 27, No. 16, pp.2425-2428, Aug. 15, 2000
(13) Duan, A. (2007), "Cooling trend in the upper troposphere and lower stratosphere over China",
Geophys. Res. Lett., 34