the importance of computer models in improving our understanding of climate change and global warming has remained a controversial issue. By feeding data on temperature, winds, solar radiation, ocean currents and a host of other climatic factors into a model, scientists can simulate what could happen over time if emissions of heat-trapping greenhouse gases increase.

These simulations are the basis of predictions that the average surface temperature of the earth will rise substantially and disrupt the world's climate in coming decades unless emissions of greenhouse gases are reduced.

The forecast of various models has been unanimous and has been widely accepted as gospel by some environmentalists and scientists. But critics