Climate predictability and simulation with a global climate model

fulfillment of the requirements for the Degree of Doctor of Philosophy Various theories of both internal and external causes of climate change on the time scale of 100 years are critically examined. Volcanic dust; solar variation; anthropogenic carbon dioxide, aerosols and heat; and stochastic variability (almost intransitivity) are all considered plausible. Data on the past variations of these forcings are collected. Observational data on climate change during the past are also assembled, and the sources of error in the data are evaluated. A seasonal, zonally-averaged, vertically-averaged, highly-parame-terizpd numerical model, similar to that of Sellers (1973, 1974) is used to test the above theories of climate change. The model simulates the present climate fairly well, but several improvements are suggested for further studies with the model. These include more accurate formulations of cryospheric and other seasonal variations, radiative flux, and oceani