Computer models are inaccurate and imprecise. They are not at the point where we can rely on them for the things were relying on them for in predicting global warming. Yet any policy that deals with global warming will ultimately be based on a computer model. Monitoring the earth's temperature is difficult because of the lack of standards historically. Global warming measurements are often taken at the Mauna Loa Observatory in Hawaii.
Some models indicate that global warming is largely Northern Hemisphere and polar phenomena.
They also indicate that nighttime temperatures are rising but daytime temperatures are stable. Furthermore, while winters are getting warmer, summer temperatures remain stable. Others argue against that claiming that since the polar ice caps are so far below zero, 4-5 degree rise in mean temperature will induce no effect on the ice caps. Global warming theorists predict such dramatic climate changes as to cause massive desertification. Anti-theorists point out that the temperature rise is in the winter and the evening hours.