I hope this is the best place for a question that’s been bothering me for a while.

I’ve read most of the posts on Richard Lindzen now & it seems to me that his entire skepticism of AGW theory — at least as far as his scientific skepticism goes — follows from his “Iris hypothesis”. That is to say, if it were proved to his satisfaction that the Iris hypothesis was wrong, and that water vapour provides the positive feedback everyone else seems to say it does, then he would concede that AGW is probably true.

Is this a fair comment?

My other question is, does anyone happen to know when he is likely to publish again? His homepage at MIT suggests he has had the following two works in progress for some time:

224. Lindzen, R.S. and R. Rondanelli (2006) On the need for normalizing satellite cloud data when applying results to climate. In preparation

225. Rondanelli, R. and R.S. Lindzen (2006) Reexamination of Iris Effect using TRMM and Kwajalein Ground Radar. In Preparation.

Best,
Alex

In a sense, the tropics (the Hadley-Walker flows) are like a “furnace in the basement” that heats the global atmosphere. If the warm tropical waters expand (like in El Nino) then the heat output grows and the mid-latitudes warm. If the tropical waters contract (like in the upcoming La Nina) then the globe chills a bit. The impact of the tropics is real.

In the 1970s, when the planet began its latest warming, something rather suddenly shifted in our basement furnace, the tropics. Its distribution of heat changed (see here ) . There seems to be more flow into the Northern Hemisphere since 1976, something like changing the ductwork settings in a house or apartment furnace.

Our “furnace in the basement”, even though it seems mundane, is very important.

the most important region is the tropics (remember that most of the earth’s surface area lies between 30S and 30N, so the 30 to 90 portion is not as big as it looks)

One half is the number I see most often as linked here.

One-half of the Earth’s surface area is contained between 30S and 30N.

Dave S, just to show I’m paying attention. This area apportionment came up in the Lorenz et al. (2006) thread and was an important factor there.

But, I imagine the question actually has to do with whether Lindzen’s experiment, which measured seasonal heating and cooling of the ocean, is really the same as increased trapping of IR by CO2.

Increased IR trapping would warm the troposphere and affect the lapse rate, which to some degree would affect the behavior of the rising air in thunderstorms, but I think that impact would be relatively small. My guess is that thunderstorms would continue to make “more raindrops /less ice” with warmth from higher CO2, just as they seem to do today due to seasonal changes.

Another aspect, as I see it, is whether the air in the thunderstorms will rise to the same height as today. I think this is an important question. If the air rises to higher, cooler temperatures, then it becomes drier. If the air doesn’t rise as far, then it is more humid. Ultimately the water vapor content of the upper tropical troposphere depends on the height to which the thunderstorms rise.

My guess is that, for a doubling of CO2, the thunderstorm height probably doesn’t change much, and to the extent that it changes, it’s higher (cooler and drier) due to more overshoots. But, that’s something that can be plausibly argued both ways.

I have no opinion (yet) as to whether Lindzen is right or wrong. But, I strongly believe that climate science would be farther along if it had more Lindzens.

David, there’s a bit more here.