Depolarization factor and other considerations.

Well, the original text from the old website that we were going to transfer cannot be found. If anyone has a copy of my old website on, please contact me.

There are a number of problems with climate models that need to be addressed. Some of the problems are:

1. The depolarization factor of air has increased over the last century due to added carbon dioxide. The effect is to make the atmosphere more reflective and cool the Earth. A change of about 0.07 W/m2 has occurred. Although small, the effect is easy to calculate and should be included in the models. It is probably omitted since it offsets the AGHG warming.

2. Subscale properties of clouds are parameterized. Just about any answer you want can probably be justified which is why clouds are the wild card in the models.

3. More layers need to be included in the radiative transfer codes of the models; otherwise, large errors is the radiation calculations can easily arise.

4. Land use changes are not fully included in the models.

5. There are a number of non-radiative sun-Earth interactions whose physics is not understood and not included in the models.

6. The spatial resolution of the models could be better. The same is true for the ocean models.

7. There are probably lots of other improvements needed that I am forgetting and other people are forgetting.

Additional discussion of model problems:

David R. Legates discusses model limitations here.

Chase et al. (2004) point out models cannot explain more warming at the surface than aloft either for forced or unforced changes in climate.

More on errors in the radiation codes here.

Patrick Michaels take on GCM errors is here.