AbstractsAstronomy & Space Science

Abstract This thesis examines global warming and the possible contribution that ozone depletion provides to this warming. An examination is performed to determine the extent of any warming/cooling events within the Earth-atmosphere system. The change in energy corresponding to this warning of the Earth- atmosphere system is estimated as being equivilent to an increase of mean solar input of 0.22W/m2. This is compared to the predicted changes of solar input for the two most common global warming scenarios: greenhouse gases and solar irradiance variance; and for a less well explored scenario, snow-ice albedo change. Examination of ozone depletion data shows that an absence of ozone in the stratosphere produces an increase in UV-B radiation at the surface of the Earth. This increase in UV-B light has not previously been thourougly examined in any of the global warming scenarios. This is presented as a fourth scenario for global warming. An analytical three layer model of the Earth-atmosphere, based on an earlier two layer model, is developed. Using this model it is determined that greenhouse gases, solar irradiance, snow-ice albedo feedback and ozone depletion can cause warming of the Earth's atmosphere. After comparison with other models, a snow-ice albedo mechanism is incorporated into the three layer model. This produces an amplification effect of any warming that occurs. Compared to the observed increase of surface temperature between 1975-2000 of 0.55 K, the model using a snow-ice albedo feedback, produced an increase of temperature of 1.4 K for greenhouse gases, 0.294 K for a solar irradiance increase and 0.119 K caused by a decrease in the ozone layer. Of the greenhouse gas, solar irradiance and ozone depletion scenarios, ozone depletion demonstrates the most realistic relative changes with a cooling of the stratosphere and a warming of the troposphere and Earth's surface as has been observed. It is concluded that ozone depletion is likely for a reasonable part of observed global warming.