New paper finds no long-term trend in stratospheric water vapor, IPCC claims opposite

A paper published today in the Journal of Geophysical Research Atmospheres by Andrew Dessler et al finds "little evidence for a long-term trend in water entering the stratosphere through the tropical tropopause layer over the past three decades."

The IPCC, however, claims "The TAR noted that several studies had indicated long-term increases in stratospheric water vapour and acknowledged that these trends would contribute a significant radiative [warming] impact."

And a 2010 paper by Susan Solomon et al is one [#7] of the 57 excuses for the 18+ year "pause" in global warming:

"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% as compared to estimates neglecting this change. These findings show that stratospheric water vapor is an important driver of decadal global surface climate change."

In opposition, the modeling paper below shows increases of CO2 and water vapor in the stratosphere act as cooling agents, not warming agents, by increasing the radiative surface area to space.

So, take your pick of the settled science:

• IPCC says there are long-term increases in stratospheric water vapor that are having a significant warming effect
• Dessler says there is no long-term trend in stratospheric water vapor 
• Solomon says decreased stratospheric water vapor is the cause for the "pause"
• The modeling paper below finds increased stratospheric water vapor acts as a cooling, not warming, agent, contradicting the warming claims of the IPCC and Solomon. 
• IPCC claims CO2 acts as the "control knob" of water vapor concentrations, but if that was true, there would not have been a 10% decrease in stratospheric water vapor 2000-2009 as claimed by Solomon above and there would be a long-term positive trend, not found by Dessler
• Tropospheric water vapor has been on a long-term declining trend, and is the source of all stratospheric water vapor as noted by Dessler above. However, if tropospheric water vapor has declined, how could stratospheric water vapor increase 1980-2000 according to Solomon, or have a "long-term increase" according to the IPCC, or have no long-term trend according to Dessler?

All mutually exclusive, but certainly not unprecedented for the settled climate science™. 

Excerpt from prior post:

3. Stratospheric cooling rates:  The picture shows how water, carbon dioxide and ozone contribute to longwave cooling in the stratosphere.   Colours from blue through red, yellow and to green show increasing cooling, grey areas show warming of the stratosphere.  The tropopause is shown as dotted line (the troposphere below and the stratosphere above).  For CO2 it is obvious that there is no cooling in the troposphere [or warming!], but a strong cooling effect in the stratosphere.  Ozone, on the other hand, cools the upper stratosphere but warms the lower stratosphere.  Figure from: Clough and Iacono, JGR, 1995; adapted from the SPARC Website.  Please click to enlarge! (60 K)  [Source] [Rebuttal] [Ozone O3 is shown as a cooling agent in the upper stratosphere, but a warming agent in the upper troposphere to lower stratosphere]

Note the scale at right side of graph indicates cooling rates and show water vapor is a cooling agent throughout the troposphere and stratosphere [only the brown colors indicate warming]. Also note that the computer-model output above demonstrates that CO2 is a very strong cooling agent in the stratosphere and CO2 is neither a cooling or warming agent of the troposphere [indicated by the light blue at the CO2 primary wavenumber at ~700 cm-1, or ~15um]. The modeled output shows CO2 to have a tiny blip of slight warming effect [light gray] at the tropopause [shown by dotted horizontal line], but clearly the net effect of CO2 shown in this diagram from the surface to the stratosphere is cooling, not warming.

Variations of stratospheric water vapor over the past three decades

A.E. Dessler et al

We examine variations in water vapor in air entering the stratosphere through the tropical tropopause layer (TTL) over the past three decades in satellite data and in a trajectory model. Most of the variance can be explained by three processes that affect the TTL: the quasi-biennial oscillation [which may be controlled by solar activity], the strength of the Brewer-Dobson circulation, and the temperature of the tropical troposphere. When these factors act in phase, significant variations in water entering the stratosphere are possible. We also find that volcanic eruptions, which inject aerosol into the TTL, affect the amount of water entering the stratosphere. While there is clear decadal variability in the data and models, we find little evidence for a long-term trend in water entering the stratosphere through the TTL [tropical tropopause layer] over the past 3 decades.