Title: Mechanisms of the Greenhouse Effect and Subsequent Implications for Climate Change and Ozone Depletion.

The greenhouse effect or greenhouse warming has been the subject of many magazine articles, newspaper articles, TV programs and other media events. In general, this warming has been ascribed mainly to increases of carbon dioxide (CO2) but can include increases of other trace gases as well such as methane (CH4), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and various nitrogen oxides. Production of CO2 is generally accomplished by both volcanoes (natural) and the burning of fossil fuels (man-made) but in recent times, the man-made causes have far outweighed the natural ones.

The greenhouse effect or greenhouse warming has been the subject of many magazine articles, newspaper articles, TV programs and other media events. In general, this warming has been ascribed mainly to increases of carbon dioxide (CO2) but can include increases of other trace gases as well such as methane (CH4), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and various nitrogen oxides. Production of CO2 is generally accomplished by both volcanoes (natural) and the burning of fossil fuels (man-made) but in recent times, the man-made causes have far outweighed the natural ones.

The physical processes of this warming due to an increase in CO2 concentration have traditionally been ascribed, in an analogous manner, to those operating in a "greenhouse". However, this analogy is not quite correct and the actual processes operating may be explained as follows. It is well known that tropospheric temperature generally decreases with increasing altitude. From the physics of "black-body" radiation, it is also known that the amount of longwave (infrared or cooling) radiation is proportional to environmental temperature according to a mathematical expression called the Stefan-Boltzmann law. As the concentration of CO2 is increased throughout the atmosphere, so does the height of the emitting source to space of infrared (or cooling) radiation due to the increased atmospheric density. Since tropospheric temperature decreases with increasing altitude, this results in the reduction of the effective emission temperature for the outgoing radiation and hence the outgoing radiation itself at the top of the atmosphere due to the Stefan-Boltzmann relationship. In order to balance the outgoing infrared or terrestrial radiation with the incoming solar radiation (which has not changed), it is necessary to raise the temperature of the entire troposphere underneath to prevent the reduction of the outgoing terrestrial radiation. In other words, the troposphere must become warmer to compensate for the above reduction of cooling radiation to space in order to maintain an energy balance at the top of the atmosphere.

This greenhouse warming has important implications for climate change and ozone depletion. On the one hand, it causes the tropospheric temperature to increase with the potential consequences attendent upon that warming. On the other hand, it decreases the upper stratospheric temperature. By a complex sequence of photochemical and chemical process in the upper stratosphere, the decrease of stratospheric temperature can potentially cause a greater depletion of ozone than we are now experiencing. The first part of the workshop will concentrate on the physical mechanisms of the greenhouse effect and understanding them. The second portion will deal with simple mathematical problems to illustrate the principles and processes of both climate warming and ozone depletion.