A general circulation model is a computer-based model that calculates and predicts what climate patterns will look like in a number of years. The GCM programs look at
several equations at once. They take into account conservation of mass, energy, momentum in a grid box system. The model focuses on each grid box and the transfer of energy between grid boxes. Once calculated you can determine a number of climate patterns; from ocean and wind currents to patterns in precipitation and evaporation rates that could affect lake-levels and agricultural levels.
