An improved version of the 2-D Zonal Climate Model in comparison with that published in WP-93-58 is presented. The modifications introduced lead to a closer agreement of the global energy distribution with current estimates and to a more complex behaviour of the coupled model, namely to the occurrence of internal oscillations in the climate system on a decadal time scale. 

The results give additional support to the idea that simplified climate models can be successfully used as a climatic part of integrated models of climate change.