I have been getting a lot of new readers of late, including a number of commenters who disagree with me fairly strongly. Welcome. Here are some general thoughts:
- Excepting some ads for Viagra and cell phones, I have never and will never delete a comment on this site. Folks are welcome to fill up the comment threads with contrary opinions. For those distrustful of the motives of skeptics, may I observe that sites like RealClimate cannot make this claim and routinely flush comments that don’t agree with the local prevailing doctrine, so make of that what you will.
- I almost never respond to comments in the comment thread itself. I like to think about and digest the comments for a while, and then incorporate them or respond to them in later posts. Trying to respond in real time in comment threads results in flame wars, not reasoned discussion.
- Unlike many skeptics, I accept that atmospheric CO2 produced by man can warm the earth. The IPCC and most climate scientists believe that the greenhouse gas effect alone may warm the earth about a degree over the rest of this century, an amount that would be a nuisance rather than catastrophic, and likely lost in the random noise of natural variations.
- However, I do not believe the earth’s climate is dominated by strong positive feedbacks and tipping points. It is this feedback hypothesis in climate models that multiplies warming to 3-4-5 degrees or more over the next century. In climate models, the catastrophe comes from feedback, not greenhouse effects, and I think this is a bad hypothesis. Believers in catastrophic warming have an interesting problem reconciling Mann’s hockey stick, which points to incredible stability in temperatures, with a hypothesis of very high positive feedback, which should make temperatures skittish and volatile. I also think that the hypothesis that aerosols are masking substantial amounts of warming is weak, and appears to be more wishful thinking to bail out model builders than solid science (while there is some cooling effect, the area of effect is local and shouldn’t have a substantial effect on global averages).
- I think the surface temperature record as embodied in the GISS analysis is a joke. I cannot respect scientists who eschew obviously superior satellite measurements for the half-assed surface temperature record just because it doesn’t give them the answer they want to here. The fact that the leader in fighting for surface temeprature measurement over satellites is James Hansen of NASA’s Goddard Institute for Space Studies is the ultimate dark irony. It’s like Bill Gates campaiging for increased abacus use in schools.
- I have built models of complex systems for years. I have been guilty many times of allowing seamingly reasonable assumptions to compound into meaningless results. Unfortunately and embarassingly, I have also been guilty of tweaking, plugging, and tuning models to better match history in order to build confidence in their future predictions. I see all too many of these same behaviors amoung climate modellers.