the Air Vent

Because the world needs another opinion

Pielke Sr. on Stratospheric Water Vapor

Posted by Jeff Id on February 15, 2010

Roger Pielke Sr. has an interesting commentary on the recent paper on stratospheric water vapor.  The paper seemed important when it came out and apparenlty isn’t getting enough attention.  Dr. Pielke has comments turned off but he has a bunch of links to his commentary.  I’ve copied the post in full because he has comments off on his blog and there are several links to other sections of his site.


Comments On “Contributions Of Stratospheric Water Vapor To Decadal Changes In The Rate Of Global Warming By Solomon Et Al 2010

The paper

Susan Solomon, Karen Rosenlof, Robert Portmann, John Daniel, Sean Davis, Todd Sanford, Gian-Kasper Plattner, 2010: Contributions of Stratospheric Water Vapor to Decadal Changes in the Rate of
Global Warming. / 28 January 2010 / Page 1 / 10.1126/science.1182488 ( see also)

has already received considerable attention on blogs (e.g. see).  [thanks to Marcel Crok for first alerting me to the paper].

The abstract of this paper reads

“Stratospheric water vapor concentrations decreased by about 10% after the year 2000. Here we show that this acted to slow the rate of increase in global surface temperature over 2000-2009 by about 25% compared to that which would have occurred due only to carbon dioxide and other greenhouse gases. More limited data suggest that stratospheric water vapor probably increased between 1980 and 2000, which would have enhanced the decadal rate of surface warming during the 1990s by about 30% compared to estimates neglecting this change. These findings show that stratospheric water vapor represents an important driver of decadal global surface climate change.”

I have two comments on the implications of this paper:

1. This study reinforces that climate variability and change is more complex than just a response to added CO2 and a few other human greenhouse gases. This conclusion has been emphasized in a variety of publications; e.g.

National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., 208 pp.

Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell,  W. Rossow,  J. Schaake, J. Smith, S. Sorooshian,  and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413


2. The evidence that the stratospheric temperatures have not been behaving as the IPCC models have predicted (i.e. with a more-or-less monotonic cooling in the absence of major volcanic eruptions of ash into the stratosphere) has been clear to anyone who has looked at the data.

I discussed this  lack of cooling  in my post

Is there Continued Stratosphere Cooling? [from March 13, 2006]. The most recent lower stratospheric data can be seen in the figure below from RSS MSU data (see Figure 7 where since about 1995 the trend has been about flat).

Channel TLS Trend Comparison

The reason for the lack of a multi-year trend in the lower stratosphere since 1995 has not received the attention it needs. Indeed, since the IPCC multi-decadal global climate models have not predicted this behavior, this is yet another reason to question the skill of their forecasts of climate for the coming decades.

12 Responses to “Pielke Sr. on Stratospheric Water Vapor”

  1. DeWitt Payne said

    I posted this at The Blackboard, but it fits a lot better here, so pardon the cross-posting.

    The problem with the stratospheric temperature seems to be that the effects of volcanic eruptions last longer than current theory predicts. We know that convection in the stratosphere can be neglected compared to radiative heat transfer. Of course, that also implies that mixing is slow because it has to be done by diffusion. But then again, with the low density of the stratosphere, diffusion may not be all that slow. Someone who cares might want to check that. Anyway. The residual plot of a linear regression of the UAH global LS data looks like this. If you assume that the linear trend is actually correct, then a volcanic eruption first heats and then cools the stratosphere. The recovery from the heating is rapid because it’s from particulates which fall out rapidly. But the cooling must be from the injection of something that takes longer to equilibrate. CO2 perhaps? That would cool by increased radiation in the IR. Or maybe it’s something that destroys ozone. That would cool by lowering heating. Since ozone is being tracked, I would have thought someone would notice that. But maybe the change is too small to be seen. Of course if that’s true than mixing between the stratosphere and the troposphere must be slower than thought.

  2. Pete said

    Let’s not forget Miskolczi, whose theory explains this AGW-anomaly:

  3. Leonard Weinstein said

    The diffusion rate is not pressure dependent until the mean free path becomes very large. Even the lower stratosphere is not low enough for that to happen. A mean free path of mm or even cm is still very small at the scales involved. I would agree that the effect of volcanic eruptions lasts longer than theory. I mentioned that in:

  4. linn said

    Water vapor fans, check this one. I hope it stimulates discussion.

    Theor Appl Climatol

    Trends in middle- and upper-level tropospheric humidity from NCEP reanalysis data

    Garth Paltridge & Albert Arking & Michael Pook

  5. Kondealer said

    Linn- how much more evidence do we need?

    Positive water vapour feedback exists only in computer models. It is up to the warmists to PROVE radiosonde data is not reliable and that atmospheric water vapour behaves the way that they want before they can so much as write a single line of code in their useless GCMs

  6. Braille said

    I’ve been following this blog since Climategate broke out in November, so I’m still fairly new to this subject.

    That being said, here’s what I’d like to know: Would an increase in water vapor in the atmosphere directly correspond to an increase in cloud cover? If that’s the case, does it not follow that there would then be more albedo effect present, thereby decreasing overall sunlight intake for the atmosphere, further distorting the temperature analysis of the paper in question?

    It sounds like they’re trying to say that water vapor in the atmosphere has been decreasing in the last decade, and that’s shifted the temperatures downward, without addressing how the overall sunlight intake of the atmosphere was altered by the decrease in cloud albedo that I would expect to occur with a decrease in atmospheric water vapor.

    As I said, I’m not sure if that connection actually exists, but it seems logical to me.

  7. RB said

    #6, NASA on clouds:

  8. Braille said

    Thanks for the link, RB. It seems from the NASA article on clouds that the net temperature change would be neutral when the total amount of cloud cover changes as long as the average type of cloud is still the same. So if the 10% decrease in atmospheric water vapor didn’t change the overall average type of cloud present, the clouds wouldn’t have any net effect on the temperature that would noticeably correspond to the amount of atmospheric water vapor. That’s really interesting, and leads me to another possible line or reasoning.

    I understand that air can hold a certain amount of water vapor, which is represented by our measure of humidity, and that the humidity of a portion of air can change if the pressure or temperature of the air changes. And I know that water vapor can condense out of the air if the temperature falls far enough, as any child can see water vapor condensing out of the air onto a cool surface, or see dew on the grass in the morning when water vapor dropped out of the air as the air cooled the previous night.

    Is it possible that this person observed a loss of water vapor that resulted from a reduction in temperature and not the other way around, as the article claims? What if the temperature dropped from something other than a change in the amount of atmospheric water vapor, and that temperature change is what caused the decrease in water vapor?

  9. RB said

    #8, I’m not sure where you are going with this, but this paper is about stratospheric cooling while clouds are found almost exclusively in the troposphere. Since models don’t predict the observation in this paper, I don’t believe they understand it well, but there’s some additional coverage here:

  10. linn said

    Dear Kondealer,

    More evidence is always better.

    GCMs need constant relative humidity for a positive feedback. That paper contradicts that assumption.

    It seems that only Dessler et al and Soden et al are quoted.


  11. RB said

    Dewitt #1,
    This supports your notion of increased CO2 leading to cooling.

  12. DeWitt Payne said

    Re: RB (Feb 16 17:48),

    The problem is the rate. The half life (or maybe 1/e life) of 14C and 90Sr in the stratosphere is about 1.3 years. Atmospheric nuclear weapons tests provided the radioactive isotopes for that measurement. That looks about right for the decay time of the warming. But the decay time of the cooling is a lot longer than that or you wouldn’t see it at all.

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