The Thin Green Line blog really wants to mix it up and debunk those scientific myths propounded by skeptics. I had my hopes up for an interesting debate, until I clicked through and saw that the author spent the entire post fact-checking Sen. Inhofe’s counts of scientists who are skeptical. Barf. I wrote back in the comments:
I just cannot believe that your “best” argument is to get into this stupid scientist headcount scoreboard thing. Never has any argument had less to do with science than counting heads and degrees. Plenty of times the majority turns out to be correct, but on any number of issues lone wolfs have prevailed after decades of being reviled by the majority of scientists (plate tectonics theory comes to mind).
If you want to deal with the best arguments from the scientific rather than political wing of the skeptic community, address this next: It is very clear in the IPCC reports (if one reads them) that in fact catastrophic warming forecasts are based on not one but two independent theories. The first is greenhouse gas theory, and I agree that it is a fairly thin branch to try to deny that greenhouse gas theory is wrong. The IPCC says that greenhouse gas effects in isolation will cause about 1-1.2C of warming by 2100, and I am willing to agree to that.
However, this is far short of popular forecasts, which range from 3C and up (and up and up). The rest of the warming comes from a second independent theory, that the world’s climate is dominated by positive feedbacks. Over 2/3 of the IPCC’s warming forecasts, and a higher percentage of more aggressive forecasts, come from this second order feedback effect rather than directly from greenhouse gas warming.
There is a reason we never hear much of this second theory. It’s because it is very, very weak. So weak that honest climate scientists will admit they are not even sure of the sign (positive or negative) of key feedbacks (e.g. clouds) or which feedbacks dominate. It is also weak because many of the modelers have chosen assumptions for positive feedbacks on the far end of believability. Recent forecasts of 15F of warming imply a feedback percentage of positive 85%**, and when people talk of “tipping points” they are implying feedbacks greater than 100%.
There is just no evidence that feedbacks are this high, and even some evidence they are net negative. In fact, just a basic reality check would make any physical scientist suspicious of a long-term stable system with a 70-85% positive net feedback fraction. Really?
When global warming alarmists try to cut off debate, they claim the science is settled, but this is half disingenuous. It is fairly strong and I am willing to accept it for the greenhouse effect and 1C per century. But the science behind net positive climate feedback is weak, weak, weak, particularly when trying to support a 15F forecasts.
I would love to see this addressed.
(**note for readers new to feedback issues. The initial warming from CO2 is multiplied by a feedback F. F=1/(1-f), where f is the fraction of the initial input that is fed back in the first round of a recursive process. Numbers above like 70%, 85%, and 100% refer to f. For example, an f of 75% makes F=4, which would increase a warming forecast from 1C in 2100 from CO2 alone to a total of 4C.)