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.
