Dupont Danisco Opens Cellulosic Ethanol Demonstration Facility
ClipperCreek Plug-in Charging Equipment CE-Certified for Deployment to Europe

Study Finds Stratospheric Water Vapor Is An Important Driver of Decadal Global Surface Climate Change

Decadal warming rates arising from (i) greenhouse gases and aerosols alone (black); (ii) that obtained including the stratospheric water decline after 2000 (red); and (iii) including both the stratospheric water vapor decline after 2000 and the increase in the 1980s and 1990s (cyan). Credit: Solomon et al., Science. Click to enlarge.

A 10% drop in stratospheric water vapor concentrations 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 CO2 and other greenhouse gases, according to a new study by researchers from NOAA Earth System Research Laboratory; the University of Colorado, Boulder; and the University of Bern (Switzerland). Their paper was published online in the journal Science on 28 January.

Earlier observations from satellites and balloons 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 ignoring this change, according to the authors.

These findings show that stratospheric water vapor represents an important driver of decadal global surface climate change.

—Solomon et al.

Over the last century, global average surface temperatures have warmed by about 0.75 °C (0.42 °C), with much of it occuring the last half. However, note the authors, the trend in global surface temperatures has been nearly flat since the late 1990s despite continuing increases in the forcing due to all the greenhouse gases.

Previous studies suggested that stratospheric water vapor might contribute significantly to climate change. The new study is the first to relate water vapor in the stratosphere to the specific variations in warming of the past few decades.

Stratospheric water vapor and radiative processes. Source: NOAA. Click to enlarge.

The stratosphere is the region of the atmosphere from about eight to 30 miles above the Earth’s surface. Water vapor enters the stratosphere mainly as air rises in the tropics.

Stratospheric water vapor changes affect the fluxes of longwave (infrared) and—to a lesser extent—shortwave (solar) radiation, and can thereby influence the temperature in the stratosphere and troposphere. In general, increases in stratospheric water vapor cool the stratosphere, but warm the troposphere; the reverse is true for decreases in stratospheric water vapor.

The researchers used data from the HALogen Occultation Experiment (HALOE) that flew on the Upper Atmosphere Research Satellite (UARS) from late 1991 through November 2005, with coverage from the troposphere to the stratosphere overs 65°S to 65 °N. Combined with two additional and independent sets of satellite data, the data provide evidence for “a sharp and persistent drop of about 0.4 parts per million by volume (ppmv)” in stratospheric water vapor after 2000.

Balloon data suggest a gradual mid-latitude increase in lower stratospheric water vapor of more than 1 ppmv from about 1980 to 2000. Other data also support increased in lower stratospheric water vapor during the 1990s of about 0.5 ppmv.

...recent observations have suggested a correlation of the post-2000 stratospheric water vapor decrease to sea surface temperature [SST] changes near the tropical warm pool region and associated cooling of the cold point that governs water vapor input to the stratosphere in the tropics. However, the relationship between SSTs in the warm pool region and stratospheric water vapor changes character (from negative to positive short-term correlations) from 1980–2009, suggesting that other processes may also be important, or that the correlation may be a transient feature linked to the specific pattern of SSTs at a given time rather than to the average warming of SSTs around the globe.

It is therefore not clear whether the stratospheric water vapor changes represent a feedback to global average climate change or a source of decadal variability. Current global climate models suggest that the water vapor feedback to global warming due to carbon dioxide increases is weak but these models do not fully resolve the tropopause or the cold point, nor do they completely represent the QBO, deep convective transport and its linkages to SSTs, or the impact of aerosol heating on water input to the stratosphere.

This work highlights the importance of stratospheric water vapor for decadal rates of warming based directly upon observations, illuminating the need for further observations and a closer examination of the representation of stratospheric water vapor changes in climate models aimed at interpreting decadal changes and for future projections.

—Solomon et al.

Authors of the study are Susan Solomon, Karen Rosenlof, Robert Portmann, and John Daniel, all of the NOAA Earth System Research Laboratory (ESRL) in Boulder, Colo.; Sean Davis and Todd Sanford, NOAA/ESRL and the Cooperative Institute for Research in Environmental Sciences, University of Colorado; and Gian-Kasper Plattner, University of Bern, Switzerland.


  • 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. Science Express doi: 10.1126/science.1182488



"A 10% drop in stratospheric water vapor concentrations 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 CO2 and other greenhouse gases"

So, this is certain?


Kelly: So this is certain.

It seems rather tentative to me after a very quick reading. But others with far more knowledge will be commenting soon.


Hate to sound cynical - this looks like a major CO2 backpedal. But in the right direction since we know that 80% of the greenhouse effect results from water vapor. The lead author Soloman is a major AGW proponent.


....It is not clear whether stratospheric water vapor changes represent a feedback to global climate changes OR is a source of decadal variability....

Can anybody answer this question with acceptable support data?


I read it as global warming would be 25% worse if not for this 10% water vapor drop.

But to know/state whether this drop is normal/abnormal, to continue/increase/decrease needs more $$$/study.


Hate to sound cynical

But you do it so well... ;^) This isn't a backpedal, it's just more information. We've always known water vapour is a GHG but its not a forcing agent. H2O, when it is in the troposphere (the lower part of the atmosphere), is a feedback effect. Simply put, any artificial perturbation in water vapour concentrations is too short lived to change the climate. Too much in the air will quickly rain out, not enough and the abundant ocean surface will provide the difference via evaporation. But once the air is warmed by other means, H2O concentrations will rise and stay high, thus providing the feedback. Or at least that's true when the H2O is in the lower part of the atmosphere. This study "Finds Stratospheric (the atmospheric layer above the troposphere) Water Vapor Is An Important Driver of Decadal Global Surface Climate Change." This water vapour is still only a feedback but because it has reached a higher atmospheric level it has a longer residence time because it's on the other side of the tropopause (the boundary between the troposphere and stratosphere).

On average the lowest part of the troposphere is warmest and temperature decreases with altitude. This promotes vertical mixing because warm air rises. In the stratosphere temperature increases with height, which restricts turbulence and mixing. Any water vapour that gets as high as the stratophere will stay there for a longer (decadal) time scales.


I would imagine, but don't actually know for sure, that the difficulty of water vapour getting into[?] and leaving the stratophere creates a lagging effect where the changes from forcing agents in the lower atmosphere are felt later. I for one would like to know if this guess of mine holds water - pun intended.

Dave R

@ai_vin - water vapor seems to stay in the stratosphere on the order of years.

This post on the Wunder Blog says it takes about 1.2 years for water vapor to reach the stratosphere.

There's a nice chart which illustrates the seasonality of water vapor concentrations in the stratosphere.


Not quite, what it says is; "Once in the lower stratosphere, the waver vapor takes about 1.2 years to travel to the upper stratosphere" and "its potency is much higher when it is located in the lower stratosphere where temperatures are extremely cold." How much time does it spend in the stratophere as a whole - both the upper and lower parts? Interesting link BTW, thanks.

Approximately 99.13% of the Earth's water vapour is contained in the troposphere (where its residence time is only about 10 days), only a very small amount reaches the stratophere in the first place.


So water vapor is labeled as the most prevalent GHG, but magically it does not contribute GW because of it's short half-life in the atmosphere? I think this article says different. CO2 is 9% to 30% of GW. What is responsible for the rest?
"We've always known water vapour is a GHG but its not a forcing agent." Sounds like semantic nonsense to me. Is it a GHG that contributes to GW or not?
Think about it. With no CO2 in the air water vapor would still have a significant GW effect. It helps keep the plant warm. Feedback? Sure, but also a direct effect. That's common sense science. It's labeled as "GHG" for a reason.

Account Deleted

water vapor is good to certain extent because it forms cloud which limits the solar radiation. Water on the earth surface vaporize when it absorbs heat thus it indirectly balances the excess heat from sunlight.

To tackle the global warming, we really need to find ways to bring water to desert area. high temperature desert surface is a really bad news.

Stan Peterson

Ferenc Miskolczi's theories of Saturated Green House Effect, in the planetary Atmosphere, speaks to variations of GHG composition in the atmsophere so that the energetic effects of all totalized GHGs are maintained and balanced.

Water vapor is added or subtracted to keep almost constant, the overall GHG effect. If more CO2 is present for example, there will be less water vapor. Less CH4, is balanced by more water vapor. All driven by Energy equilibrium considerations.

Recent research such as this and others, the Lindzen ERIS observations and resultant hypothesis on tropical storms, and the recent, outstanding paper by Lindzen-Choi on ERBE satellite results, all seem to confirm that the additions of GHGs does not function to decrease IR energy escaping into Space, anymore. Or in other words, more CO2 does not add to global warming the Earth.

This may also be viewed as evidence of a negative feedback to additions of CO2 to the atmosphere, doing away with the concept of Catastrophic Anthropogeninc Global Warming.

In effect the Earth appears to follow an energetic equilibrium, not allowing GHG changes to alter the basic temperature much, while tending to drive pertubations back toward were they were originally.

Stan Peterson


The Earth does have a way to bring water to desert areas, its called ...R-A-I-N.

Account Deleted

stan, i agree with you but the question is how can we make rain fall frequently on deserts

The Goracle


OUCH!!! So what the deniers, the skeptics, the stoopid have been saying all along may be true?!?! These "researchers" MUST all be FIRED immediately.

How can we possibly change marketing plans, **again**, mid-game? CO2 has been our Satan for years and now we have research showing the H2O is actually Satan. It's going to be tough regulating the emission, transportation, and storage of the pollutant H20 but we MUST do it in order to save the planet!

Lets hear it Algore!!!



@Goracle: I agree, all we need to do is to call it something sinister like Dihydrogen Monoxide and the masses will fall for it. See for more information on this silent killer :-)


It is well accepted that quick cycling water vapour in the atmosphere is an ongoing (about 100%) natural phenomena and constitutes up to 95% of the GHG average baseline. Without it, we would not be here to discuss climate changes because Earth would be as dry as Mars and the Moon.

Water vapour (WV) is and has been a major climate regulator. The sun + current Earth condition are probably the major water vapour generators. There is a high probability of a snowball effect between rising ground temperatures and atmospheric water vapour content. By progressively destroying wet lands, tropical and other forests, to make room for paved roads, flat roof buildings, parking lots, mono-culture farms etc we are modifying the natural WV cycle, GHG and climate. Mankind will have to address this before deserts and waste lands cover 80 + % of the planet.

As the planet gets hotter and desertifies, atmospheric water vapour content will progressively go down and the climate change cycle will reverse.

We can do something about the other 5% GHG created by 20+ other gases.

It is also very well accepted that CO2 accounts for about 99.438% (and rising) of the non-water vapour GHG.

Reducing CO2 emissions (and many other GHG gases) could reduce overall GHG and contribute to rising climate reversal.

Another potential problem would be to over do it and drive the Earth into an early negative climate change and open the door to the next cold-freezing period.

Will mankind be able to modulate future natural climate cycles? If so, to what extend?


consider this:
“Did Early Global Warming Divert A New Glacial Age?”
- December 2008


Now THAT is an interesting idea, but I'll wait to see if it has gotten pass the peer review process.

The Goracle


I'll wait to see if it has gotten pass the peer review process.

It has already been shown that the Climate Change® peer review process is simply a process used to keep out valid explanations for Climate Change® that do not claim that Climate Change® is caused by humans. Please see the EAU, et al., emails released by the whistleblower for proof.



If any of the AGW claim had real merit - why did the "world's leading climate scientists" have to falsify, hide, delete, and manipulate the data to prove it??


Goracle, Sulleny:

Are you compensated in any way for your posts?

Do you post under multiple names?

Steve Funk

So, the question will be, is variation in stratospheric water vapor a predictable long term trend or something cyclical. Coby Beck's website
claims that water vapor varies as a function of temperature, and is therefore a feedback, not a forcing. I would like to read the whole study by Solomon et al.



So water vapor is labeled as the most prevalent GHG, but magically it does not contribute GW because of it's short half-life in the atmosphere?

No. It contributes, but there is only one way to influence the water vapour content of the atmosphere that I know of: by changing the temperature of the atmosphere. Any increase in temperature (for example by adding CO2) leads to more water vapour and additional heating. That is an inevitable physical law, and the reason why water vapour is called a feedback (although I prefer the term amplifier) and not a forcing. Physics, not semantics.



If any of the AGW claim had real merit - why did the "world's leading climate scientists" have to falsify, hide, delete, and manipulate the data to prove it??

Before the leaked emails, the data was already available, but it was not easy to get for a non-scientist. Since the email leak, the data has been made available to anyone. And what have the deniers found? Nothing. Zip. Nada.

As an exercise in critical thinking, start looking at the data that purportedly has been deleted and hidden and manipulated and how exactly that gave the scientists the desired results. And how would the results look completely different when those deletions and manipulations had not taken place? I am eagerly awaiting your analysis. Time to support your accusations with evidence.

The comments to this entry are closed.