The ozone layer, more than 12 miles up in the atmosphere, is formed and heated by high-energy, ultraviolet radiation from the Sun. When the amount of ozone is reduced (depleted), more of this sun-burning, cancer-causing radiation reaches Earth, cooling the ozone layer and warming Earth. This ultraviolet energy is 48 times hotter, 48 times more energetic that infrared radiation absorbed by greenhouse gases.
“There simply is not enough thermal energy absorbed by greenhouse gases to have much effect on global temperatures,” explains Dr. Peter L. Ward, a geophysicist and program leader who retired after 27 years working with the United States Geological Survey.
Energy absorbed by greenhouse gases has customarily been overestimated by scientists assuming light travels through space as waves, where energy is proportional to the amplitude of the wave squared. But waves result from deformation of the chemical bonds that hold matter together. There is no matter in space and there are no chemical bonds. Electromagnetic radiation, including visible light, travels through space simply as frequency, just as radio signals are transmitted. The thermal energy contained in this thermal radiation is directly proportional to its frequency: higher frequency means higher energy.
Ozone depletion began increasing in the early 1970s caused by increasing use of human-manufactured chlorofluorocarbons (CFCs). CFCs, at that time, were becoming widely used as refrigerants, solvents, and spray-can propellants. When these gases reach the ozone layer, they are broken down by ultraviolet radiation, releasing chlorine atoms that deplete ozone. Global temperatures began to rise.
Concern over the growing Antarctic Ozone Hole led to the Montreal Protocol, effective in 1989, agreeing to reduce CFC emissions. CFC concentrations began decreasing by 1993, stopping the increase in ozone depletion by 1995, and stopping the increase in temperatures in 1998. Global temperatures have not risen for the last 16 years even though greenhouse-gas emissions continue to climb.
Ozone is also depleted by volcanic eruptions emitting chlorine and bromine. Effusive, basaltic volcanic eruptions, typical in Hawaii and Iceland, cause global warming. Explosive volcanoes, on the other hand, such as the eruption of Mt. Pinatubo in the Philippines in 1991, cause early warming but net cooling because they eject megatons of sulfur dioxide and water just below the ozone layer, forming a mist or aerosol that reflects and scatters sunlight, cooling Earth for about three years.
Climate throughout geologic time appears to be controlled primarily by the duration of effusive volcanoes causing warming and the frequency of explosive volcanoes causing cumulative cooling.
“Because global warming is caused by ozone depletion,” Ward says, “reducing carbon dioxide emissions is unlikely to have any significant effect on reducing global warming.”