Replies

Hi Palmer,

Thanks for your reply. I think your quote of Lindzen slightly mis-characterizes the point he was making in that article. What he was trying to say was that "IF you accept the fact that the 0.7C rise in temperature WAS due to the increased CO2, then BASED UPON THEIR MODELS it should have actually been more. He is not a believer that the CO2 increase led to the 0.7 degree temperature increase. If he accepted that, then he would presumably have to accept the alarmists projections of continued increases as future CO2 increases occur.

Regarding the water vapor feedback... just how proven is this? Is it proven beyond the fact that it is modeled in the GCM's to produce matches with past temperature records?

Regarding solar variability, I hear a lot of different opinions on just how much the sun has been increasing through various measurements. I think the jury is still out on just how the sun's variations affect the earth and our climate. I am very much aware of how little the IPCC attributes recent changes to solar variability. The following graph comes from the IPCC-friendly RealClimate.org's own website:

This graph clearly shows a dramatic increase in sunspot numbers and solar modulation. Notice the steady increase from 1900 to the present. The IPCC bases, as I understand it, their conclusion that the sun can not be responsible for the most recent temperature increase based upon the roll-off at the end of the graph, suggesting therefore that it could not be a forcing. As I understand it, they attribute some of the 1910-1940 steep temperature rise (a rise as steep as in recent decades) on increased solar irradiance. But they say that since the sun's irradiance in the last decade of the 20th century dropped off, that it could not be the cause. They don't want to consider a water vapor feedback from solar warming that could amplify the suns's increases, but they are eager to explain an increase of 1/100th of 1% increase in CO2 make-up of the atmosphere causing a large amplifying water vapor feedback.

Regarding GCR flux, I think the jury is still way out on just how much of an impact it may cause. There has been an orchestrated effort to discredit Svenmark, Calder and Shaviv in their efforts to uncover the link between GCR's and cloud formation. But they are going to continue their research anyway, and efforts to impede their research should be condemned by all scientists.

Often, sunspot numbers are considered a significant metric, but the paper by Jason Kirkby in 1998 at CERN, in Switzerland. Page 8 of this pdf document:

CLOUD Chamber (Cosmics Leaving OUtdoor Droplets Chamber)

Contains a very interesting correlation between average sunspot cycle length rather than sunspot number. Whether this really amounts to anything, I don't know, but I do believe we have a LOT more to find out about how the sun affects our climate than we currently know.

Hi Aaron,
As RealClimate is fond of pointing out, water vapor essentially *is* feedback. I think that's true as the water cycle dwarfs any water vapor forcing from volcanoes by many orders of magnitude. It is also mostly a positive feedback although at higher concentrations it can become negative (e.g. certain types of clouds). It also happens to fit their agenda that CO2 is mostly a forcing and mostly not feedback from warming although they would admit to some slow feedback.

The RealClimate approach to solar irradiance, cosmic rays and anything else that's not part of the agenda is strictly divide and conquer. If there's a solar component then it's small and slow (I tend to agree). Cosmic rays are unknown and small, Milankovitch is large but slow, etc, etc. Then they improperly use ancient ice cores to show that CO2 was always slow or bounded in the past which is ridiculous considering there are 1000's of years between measurements in the oldest cores so any fast rise (and fall) that occured would be invisible.

You correctly point out that once they have divided and conquered the non-CO2 forcings they rule out (and usually don't bother to model) any water vapor feedback from them.

In the end there are many factors involved and the twin approaches here at FR (discredit CO2 and toss around new forcings out of context) is not particularly convincing to me.