In order to account for the actual, much-lower rates of temperature rise, modelers have inserted a number of cooling factors into their models, particularly sulfate particles produced by burning dirty coal. The modelers postulate that sulfate particles brighten clouds that cool the surface by reflecting sunlight back into space. The physics of atmospheric warming are uncontroversial, as is the fact that atmospheric carbon dioxide is increasing. Climate computer models try to replicate this process so as to predict what the earth s climate will be over the next century. So far, though, the model results do not match the actual temperature trends found in the satellite record.
Clouds are probably the main cause.
Richard Lindzen, a professor of atmospheric sciences at the Massachusetts Institute of Technology, has published a study in the current issue of the Bulletin of the American Meteorological Society which could explain what s going on. High, thin cirrus clouds tend to act as insulators, trapping heat before it can radiate into space. Looking at weather satellite cloud data and ocean surface temperature data for the western Pacific, Lindzen found that for every 1 degree centigrade increase in ocean surface temperature, there is an average 22 percent decrease in cirrus cloud cover. Lindzen suggests that cumulus clouds over warmer seas produce rain more efficiently thus leaving less moisture in the atmosphere to produce heat-trapping cirrus clouds. Preliminary calculations using this cloud thermostat cut computer climate model temperature estimates of global warming by almost two-thirds.