An anonymous reader writes: University of Wisconsin climatologist Reid Bryson has argued that the climate is changing but carbon dioxide is not the main cause. According to Bryson, water vapor absorbs 80% of the heat from the Earth's surface, and carbon dioxide absorbs only 0.08%. He believes that computer models that predict future climate put too much emphasis on carbon dioxide and not enough on water vapor and cloud coverage. Ice core studies show atmospheric carbon dioxide tracking closely with temperatures, but also show that carbon dioxide changes follow temperature changes, rather than lead. Bryson blames the long-term natural variation of the climate for our current warming: 'All this argument is the temperature going up or not, it's absurd. Of course it's going up. It has gone up since the early 1800s, before the Industrial Revolution, because we're coming out of the Little Ice Age, not because we're putting more carbon dioxide into the air.'