There are also naturally occurring swings and shifts in the system. One hundred million years ago, during the Mesozoic era , the average temperature was 20 degrees warmer and alligators lived in Alaska. All this makes divining what is happening to the climate a difficult exercise. As the researchers added carbon dioxide to the models, the temperature increased. F. The models, however, are only crude approximations of natural processes and there are some phenomena, such as cloud formation, that are poorly understood.
Bad data can lead to bad forecasts.
When run for this century, for example, the models predict a two 2 degree F rise in average global temperature. In fact, it appears that temperatures have risen only one 1 degree. As a result, critics, including Lindzen and Balling, argue that the models are grossly overstating the warming effect. The models, however, are not the only signs of warming. An increasingly strong case for climate change is being made with other evidence and measurements.