2. Two scientists at the University of Alabama-Huntsville, in a 1998 report, produced evidence from high altitude satellite measurement of atmospheric temperatures, that the planet actually cooled slightly in 1997. This evidence supports scientists who claim we still do not know enough about the earth's highly complex climate to draw conclusions of global warming.
3. Computer simulations claim that the greenhouse effect should have raised global temperature by about one degree Celsius. However actual temperature records only show a rise of 0.5 degrees over the century peaking before 1940 and then declining until the 1970's since it has risen modestly by 0.2 degrees. As 80% of carbon dioxide emissions have occurred since 1940, then the rise of 0.5 degrees before 1940 must natural. Based on the evidence of sunspots who Galileo began observing in 1610 suggests that computer models overlook the influence of sunspots on temperatures. Sunspots are cooler darker areas of strong magnetic fields. These sunspots peak and change direction every 11 years or so creating 22 year cycles. The sun is brightest at peak sunspot periods thus is brightest during short cycles. Changes in the length of the cycle and in northern hemisphere land temperatures are closely correlated over three centuries. If this is correct then changes in the sunspot cycle would explain the average temperature change of about one degree Celsius over the last 100 years.