Sunday, December 21, 2008
The art and science of climate modeling has improved enormously over the years with both an increasing sophisticated understanding of climatic feedback effects and the empirical knowledge that can set the parameters or values used in the models. A 2005 study by Wentz indicated that global rainfall is increasing about 1.5% per decade, about five times (500%) faster than the value used in the 4th IPCC Assessment Report. A new study by Aumann and his colleagues presented at the fall meeting of the American Geophysical Union found a strong correlation between the frequency of very high clouds and seasonal variations in the average sea surface temperature of the tropical oceans. For every degree Centigrade (1.8 degrees Fahrenheit) increase in average ocean surface temperature, the team observed a 45-percent increase in the frequency of the very high clouds. At the present rate of global warming of 0.13 degrees Celsius (0.23 degrees Fahrenheit) per decade, the team inferred the frequency of these
storms can be expected to increase by six percent per decade. These two studies will help improve climate models since clouds and rain have been "the weakest link in climate prediction," according to Aumann.