ars ago, could provide an exact description of today's climate. Only recently have models been developed that are capable of realistically depicting the present global climate without a lot of tinkering-adjustments often called "fudge factors" (Suplee 47). The reason for this is that only the most powerful computers are fast enough to handle the job, and in part, that some aspects of climate change are still mysterious (Suplee 47). Even the fastest computer cannot take in all of the natural variability of the climate in the effort to diagnose human induced climate changes. Apparent long-term trends can be artificially amplified or dampened by the contaminating effects of undiagnosed natural variations (Mahlman 1416). Significant reduction of key uncertainties will require a decade or more. The uncertainties concerning the responses of clouds, water vapor, ice, sulfates, and ocean currents remain formidable (Mahlman 1416). Cloud cover in models is also poorly treated and inaccurately predicted in GMC's (Lindzen 3). Current models depend heavily on undemonstrated positive feedback factors to predict high levels of warming. According to Kevin Trenberth, chief climate analyst at the National Center for Atmospheric Research in Boulder, Colorado:
             All GMC's project global warming, but they can provide only a range of projected temperature change. The warming could be a half a degree C (1degree F) over the next century, or it could be as much as three times greater than that. Used properly, models can be useful tools, but they cannot solve the problem (Silverberg 54).
             There is ample evidence that the average equatorial sea surface has remained within plus or minus one degree C of its present temperature for billions of years, yet current models predict average warming of two to four degrees even at the equator (Lindzen 4).
             There are multiple reasons for these discrepancies with the computer simulati...