Dr. Roy W. Spencer is a principal scientist at University of Alabama in Huntsville.
Statements on global warming
- Everybody assumes that the earth naturally is in radiative balance, and yet we don’t even know that from an observational point of view. It could be that the earth is constantly out of radiative balance. We know it certainly is locally, because that is what drives the weather. Weather is a complex, fluid system that is forced by heat inequalities around the earth; that is what drives it. I wouldn’t be surprised if there were substantial imbalances in the earth’s radiative budget and yet everybody starts out assuming that it is in balance. My personal opinion is that the modelers who believe this are mostly physicists rather thanscientists and they not as familiar with the climate system complexities that we atmospheric types tend to focus on. All of these assumptions about the Earth being in radiative balance are made by modelers, but I don’t think anybody had demonstrated them. They are just assumptions. 
- One thing I try to point out to people, and Dick Lindzen has pointed this out in the past, too, is that, as most of you probably know, about ninety percent of the earth’s greenhouse effect is water vapor, then carbon dioxide, methane and some trace gases. The water vapor con-centration in the atmosphere goes up and down quite a bit, but it is self-regulating. Things don’t get too warm before precipitation systems suck the water vapor out again. I don’t understand how we can know how much warming there will be with global warming until we understand how precipitation systems change with warming. We don’t under-stand that, and I have papers from modelers who have said the same thing. Modelers don’t like to talk about what they don’t know. So until we understand these natural proc-esses that remove the earth’s primary greenhouse gas, water vapor, from the atmosphere – which is a self-regulating part of the earth keeping a constant temperature – I don’t think we can predict how much warming there will be due to increasing CO2. It is a mat-ter of faith again, I think. We are not saying that we don’t believe that there can be sig-nificant global warming. As John said, if you add CO2, something has to change. But things are changing all the time anyway. The big question is: So what? How much is it going to change, compared to other things? And what can you do about it? 
- It should come as no surprise that there is no shortage of environmentalist exaggeration and half-truth that also "misleads people about climate change". After all, professional environmentalists and climate scientists might lose their jobs if the global warming problem was to ever go away. (...) As a result, everyone in the global warming debate is biased. People can expect that corporations will emphasize research that supports their opinions and goals, while environmental lobbying groups will do the same. Everyone has financial motives, and government-funded scientists and environmentalists acting as if they own the moral high ground is an increasingly tiresome pose.