Bio diesil...that is susstainable...the ultamate solution...here is another extract...
Professor Herman’s guest weblog follows.
After reading all sorts of statements from a wide range of scientists during the past few months, I am totally surprised at how knowledge and expertise must have been accumulated during this time period. I refer to predictions that most, or all warming during the past 50-100 years is due to greenhouse gases with 90% certainty. I had always been told that the models being used had considerable uncertainty so that I wonder how this degree of certainty has now been achieved.
I am, myself, not a climate expert, but rather a scientist who has spent most of his career working on problems of atmospheric radiation science and remote sensing, I have been reluctant to speak out on the climate change subject. However, I think I have to at this time. The recent IPCC summary report has just informed me, and the rest of the world, that there is little doubt but that the global warming we are experienced is due to greenhouse gas emissions into our atmosphere. That conclusion was really surprising to me, it having come from a world wide group of supposedly outstanding climate experts.
Let us first of all, settle what we can say with reasonable confidence. If we add infra red absorbing gases to our atmosphere, two things must result:
1. So long as the absorption of incoming sunlight does not change ( and the addition of the so-called “greenhouse” gases does not significantly effect the absorption of solar radiation) then the radiative equilibrium temperature of the entire earth atmosphere will not change
and
2. Due to the addition of IR absorbers ( the greenhouse gases), the lower atmosphere should warm and the upper atmosphere should cool. Now the next steps are where the questions arise. How much will the lower atmosphere warm? The very act of changing these atmospheric temperatures sets into action numerous feedback effects, one of the most important being the increase in water vapor as a result of the increased temperature. This feedback is of course, well known. Now, when I ask the question as to what changes in cloud cover, cloud height, etc. will result from the increased temperatures and the increased water vapor, there seems to be a unanimous agreement that “we don’t really know”. In fact, even if we did know, the models still can’t accurately predict the resulting temperature changes as a result of changes in cloud parameters. Yet, this feedback could substantially alter temperature predictions.
Now, the models also predict that the mid tropospheric warming should exceed that observed at the ground, but satellite data contradicts this. We have been looking into this problem here at the University of Arizona, and have concluded that the satellite temperatures from the UAH group are the most accurate, and these, after being corrected for stratospheric cooling, orbital drifts, hot target changes, etc. still show less tropospheric warming than do the ground temperatures. A paper addressing this will be submitted for publication shortly. If the models cannot accurately predict the temperature trends in the mid-troposphere, how accurate can they be at the ground?
I am also puzzled by the local area predictions that are becoming almost a daily happening. Here in Arizona, we are told we will experience severe drought, unbelievably hot temperatures, etc. If the climate warms enough, we would expect the global weather patterns to migrate poleward. While this would likely diminish our winter rains here in Arizona, it would also advance the Monsoon easterlies further north in the summer, likely producing more summer rains and a longer summer rainy season. It would also cause cooler summer temperatures as the sub-tropical high would be further north and we would not be exposed to the subsidence that results in our high temperatures now. The increased cloud cover due to the increase in monsoon rains would also help cool daytime temperatures Whether the net result would be a decrease, an increase, or no net change in rainfall I can’t say, but the models can’t predict this either. Yet the forecasts of what will happen are being made.
Another point I would also like to make is with respect to the rather rapid increase in temperatures that we have experienced over the past 10-15 years. Can the models explain this by the addition of greenhouse gases? I don’t believe the increase in CO2 has taken on a similar shape.
The above are but a few examples of uncertainties that exist. There are others. I point them out only to raise the question as to how statements about our past warming, and even our future weather can be made with 90% certainty while such important questions still exist.
remainder of article at:
http://climatesci.colorado.edu/2007/04 (4/6/07)