Recently, Professor William R. Cotton of the Department of Atmospheric Science at Colorado State University was asked the question below,
“I heard you are speaking out about global warming. Do you have a presentation you use that could help me understand your reasons?”
Bill has okayed my posting of his answer which is given below.
“I am not exactly speaking out against global warming. But, I don’t think the science is as solid as many lead us to believe. Don’t get me wrong, the science of how greenhouse gases directly affect climate is strong. But where it gets messy is all the feedbacks in the system that the theory relies upon and most particularly the role of clouds. Also when it comes to future scenarios (predictions?) decades or longer I point out there are many other factors affecting climate and some of these can be quite large but often are not predictable. Many of these are related to aerosols either natural (volcanoes) or manmade. Then there is also the wildcard with respect to solar variability impacting climate. I think there is something going on there that we just don’t understand. I try to keep up on papers in that area and so far am not convinced about their physical arguments especially the cosmic ray/cloud cover arguments But just because we can’t explain it doesn’t mean something important isn’t happening.
I have attached a copy of the recent talk I gave at the University of Tel-Aviv. I didn’t put it on a slide but I also point out that this position is purely from my personal scientific evaluation. My book on “Human Impacts on Weather and Climate,” 2nd Edition by Cotton and Pielke published by Cambridge is out by the way.
I also point out that I am very “green” as I ride a bicycle to and from work 12 miles a day, I have a Toyota Prius, fly a sailplane, sail boats and paddle kayaks, have an electric lawnmower and weedwacker, florescent lights throughout the house, and support reducing pollution of all sorts.
I put the figure showing the correlation between greenhouse gas emissions and population to show that the bottom line is we are overloading our planet and that as long as we keep putting more and more people on it we will be increasing the likelihood of serious impacts on water resources, air quality, and weather and climate. However, as a scientist I have to draw the line between being “objective” and being an advocate of policies.”
Professor Cotton’s powerpoint talk, entitled “Global Climate Change: A Skeptic’s Perspective“, which provides more depth into his research and perspective on climate change is available.