“An increase of 0.08 prcm in the global average w would result in the same
temperature rise – or a decrease by the same amount could completely hide the greenhouse effect of the CO2 doubling.” The atmosphere water content is 2.62 prcm in these calculations, so 0.08/2.62 = 3.0%.

A 0.08 prcm change in water vapour, with the same percentage (3%) change throughout the atmosphere, or a doubling of CO2 from 366 ppm, would increase the optical depth by 1.29%.

The temperature change is a direct function of optical depth, (but not a linear function), so either a 3% increase in water vapour or a doubling of CO2 would cause the same temperature increase. Using the global average TIGR radiosonde archive, this temperature increase is 0.48 C assuming no change in outgoing longwave radiation. This is the long term equilibrium condition, as for a stable climate, the incoming radiation must equal the outgoing radiation.

You say “I am a little confused about what those optical depth measurements even represent. Are they for a given wavelength of radiation or some sort of weighted average over a range of wavelengths?”

HARTCODE calculates the spectral radiation fluxes using in a spherical refractive environment using 9 streams, 150 vertical layers, 11 greenhouse gases to a 1 cm^-1 spectral resolution. The total flux optical depths are computed as the negative natural logarithms of the atmospheric transmittance, being the ratio of the transmitted flux to the upward surface radiation flux. This is integrated over the full spectral range 1 – 3000 cm^-1 and integrated over the solid angles.

I previously remarked “This graph shows that changing the water vapour content at the 300 – 400 mb level has 41 times the effect on out-going radiation as the same change near the surface. So only water vapour changes in the upper atmosphere matter.”

You thought “that would imply that we have had changes in water vapor between 1948 and 2008 that would be the equivalent of something like 5 or 6 halvings of the CO2 levels”

But you forget that the absolute amount of water vapour, specific humidity, at 300 mbar is only 2.25% of that at the surface. In the layer 300 – 400 mbar, over the last 60 years the water vapour content decreased by 55 g/m^2, but in the layer 850 mbar to surface the water vapour content increased by 165 g/m^2, according to the radiosonde data.

Concerning the Soden 2005 paper, the assumption of the T12 response to increased water vapour is contradictory. T12 is the radiation measurement at the water molecule 6.3 um band. An increase in water vapour would reduce the radiation measured at constant temperature, and a temperature increase would increase the T12 signal at constant water vapour mass.

But the paper says at the top of page 843, “As the atmosphere moistens, the emission level for T12 increases as a result of the increasing opacity of water vapor along the satellite line of sight.” Huh!! This must be a typo. This should say “emission level for T12 decreases…”

Soden assumes without any justification that the temperature effect on T2 is the same as the temperature effect on T12. This doesn’t make sense. T2 signal comes from the oxygen molecule in the upper atmosphere. The T12 temperature signal is radiation from the surface and non-water vapour molecules in the atmosphere that isn’t absorbed by water vapour. This is a completely different type of temperature signal, and the signals come from different regions of the surface-atmosphere system. The T2 is an emission signal, while the T12 is an attenuation signal. The T2 – T12 calculation makes no sense. There is no justification for assuming T12 is a relative humidity indicator. It is likely wrong because it disagrees with direct measurements.

By the way, I realized that I am a little confused about what those optical depth measurements even represent. Are they for a given wavelength of radiation or some sort of weighted average over a range of wavelengths?

The statement “A 3% increase in water vapour has the same effect (on optical depth) as a 100% increase in CO2″ was determined by HARTCODE line-by-line (LBL) code.

Okay…The new parenthetical statement you have added changes the meaning considerably. I had thought you meant that the radiative effect (radiative forcing) due to a 3% increase in water vapor is the same as that due to a 100% increase in CO2. However, as you note, “a change in optical depth is not proportional to a change in out-going long-wave radiation”, so this 3% vs 100% claim is really irrelevant to their effects on the global temperature.

Of course I know that Soden looks at the T12-T2 difference, but we don’t know if this cancels the temperature effect because we don’t know the relative contribution of water vapour and temperature to the T12 signal.

I don’t understand what you are saying here. The changes in T2 should reflect the part of the change in T12 that is due to temperature, because T2 is sensitive only to temperature and not water vapor. This is why Soden subtracts one from the other in order to remove the effect of the change in temperature. (In reality, the T2 and T12 don’t have exactly the same weighting over the various atmospheric levels but they are quite close so the cancellation of the temperature variation part of T12 should be quite good.)

And, as I noted, Dessler uses different satellite data to look at the changes in water vapor.

Nature has many ways to reduce specific humidity. In the tropics, every time the air temperature increases, thunderstorm clouds form and more SW light is reflected, the OLR increases, and rain increases, until the maximum air temperature is passed. See “the thermostat hypothesis”:
http://wattsupwiththat.com/2009/06/14/the-thermostat-hypothesis/

But it seems to me that such a hypothetical mechanism would not explain how there is a positive water vapor feedback for temperature fluctuations on, say, approximately annual timescales (where I believe that both the satellite and radiosonde data show it to be operating) but somehow does not occur on the longer multidecadal timescales.

” “A 3% increase in water vapour has the same effect as a 100% increase in CO2.”

Really? So, if your radiosonde data is to be believed and is representative of the drop in water vapor at the atmospheric levels important for the greenhouse effect, that would imply that we have had changes in water vapor between 1948 and 2008 that would be the equivalent of something like 5 or 6 halvings of the CO2 levels (e.g., dropping the CO2 levels by something like a factor of 50.)”

The statement “A 3% increase in water vapour has the same effect (on optical depth) as a 100% increase in CO2″ was determined by HARTCODE line-by-line (LBL) code. Accurate LBL codes are widely available for flux density and optical depth computations. A 3% increase in water vapour means we increase the water vapour content at all levels of the atmosphere by 3%.

In this calculation it is necessary to have the correct water vapour profile. You can not use the USST-76 standard atmosphere, which is inputted into the MODTRAN source code. The USST-76 has far too small H2O amount compared with the global average from TIGR, or the NOAA ESRR databases. Here is a comparison of USST-76 with the TIGR and NOAA water vapour profiles. You can see that the TIGR and NOAA profiles from 300 mbar to surface are almost identical, but the USST-76 profile has much less water vapour.

http://www.friendsofscience.org/assets/documents/FOS Essay/NOAA GAT USST76.jpg

You suggest that this somehow conflicts with the fact according to radiosonde data, water vapour specific humidity has declined 17% from 1948 to 2008 at the 400 mb level. You can’t compare a total atmosphere calculation with a water vapour decline at one level in the atmosphere. Specific humidity has increased through most of this period at the 950 mbar level, and from 1970 to 2008, specific humidity hasn’t changed much from 600 mbar 850 mbar levels. You have to compute the total atmosphere optical depth, as we have done and shown in the optical depth graph I previously presented and shown here:

http://www.friendsofscience.org/assets/documents/FOS%20Essay/Optical%20Depth2008.jpg

This shows that the decline in water vapour content in the 300 to 400 mbar levels offsets most of the warming effects of increasing CO2 and increasing water vapour at lower levels. This is not at all like “5 or 6 halvings of the CO2 levels”.

The early data may not be reliable. If you ignore the early data, the declining upper troposphere water vapour may still offset a significant portion of the CO2 effect. Nevertheless, it is clear that the declining water vapour during the last few decades has caused a negative feedback to CO2 emissions, contrary to computer models. You should also note that a change in optical depth is not proportional to a change in out-going long-wave radiation.

Of course I know that Soden looks at the T12-T2 difference, but we don’t know if this cancels the temperature effect because we don’t know the relative contribution of water vapour and temperature to the T12 signal.

Nature has many ways to reduce specific humidity. In the tropics, every time the air temperature increases, thunderstorm clouds form and more SW light is reflected, the OLR increases, and rain increases, until the maximum air temperature is passed. See “the thermostat hypothesis”:
http://wattsupwiththat.com/2009/06/14/the-thermostat-hypothesis/

[REPLY - OTOH, we don't delete opposing points of view like on nearly all pro-AGW blogs. Consider that. ~ Evan]

I respect that…practicing what you preach. Thanks.

Chris
Norfolk, VA, USA

Thanks. I do try to practice what I preach.

Ken Gregory,

Thanks for your reply. You say:

The paper assumes the T12 signal is proportional to relative humidity only because this signal has not changed much since 1982, and climate models project constant relative humidity. This is circular reasoning.

The Soden paper does not use T12 alone. It also looks at T2. By looking at T12-T2 it is able to at least approximately subtract out the effect of changing temperature and just get a measure of the changing absolute humidity. Dessler and co-workers (list of papers here: http://atmo.tamu.edu/profile/sub/239 ) have also independently looked at humidity as measured by satellites; I haven’t looked in much detail at their method of doing it but it uses different satellite measurements and they get similar results to Soden.

As for the radiosonde data, as Soden et al explain: “Although an international network of weather balloons has carried water vapor sensors for more than half a century, changes in instrumentation and poor calibration make such sensors unsuitable for detecting trends in upper tropospheric water vapor (27). Similarly, global reanalysis products also suffer from spurious variability and trends related to changes in data quality and data coverage (24).” [I couldn't find Ref. (27) but Ref. (24) is this paper: http://www.cgd.ucar.edu/cas/Staff/Fasullo/refs/Trenberth2005FasulloSmith.pdf ]

You also haven’t addressed the other reasons that I mentioned for the radiosonde data not being believable including the amount of negative radiative forcing it would imply (if your estimate of the strength of water vapor relative to CO2 is correct, which I admittedly don’t believe either) and the idea that the specific humidity is well-correlated with temperature fluctuations on the annual timescales but then fails to be correlated on the longer timescales.

Radiosonde measurements from thousands of weather balloons show that specific humidity in the upper troposphere has been falling over the last 60 years, especially in the 300 and 400 mbar pressure range. These are direct measurements.

You suggest that the humidity trends of the radiosonde data are not believable because they conflict with satellite data, which according to a paper Soden et al 2005, show increasing humidity in the upper troposphere.

We have confidence in the temperature measurements from satellite data because they are verified by radiosonde measurements. The satellite temperature measurements are calibrated by comparing individual satellite pixel readings to corresponding radiosonde readings.

Satellites do not measure humidity, they measure radiation emissions. The Soden paper relies on data from the High Resolution Infrared Radiometer Sounder (HIRS) which measures emissions from the 6.7 um absorption band, channel T12, and the Microwave Sounding Unit T2 channel, which is sensitive to temperature from oxygen atom emissions. The paper claims the T12 signal is sensitive to relative humidity because it response to both temperature and water vapour content. The paper only assumes that T12 varies with relative humidity, but the relative contribution of temperature and water content to the T12 signal is unknown.

The paper assumes the T12 signal is proportional to relative humidity only because this signal has not changed much since 1982, and climate models project constant relative humidity. This is circular reasoning. The T12 signal needs to be calibrated to radiosonde measurements to determine what it is measuring. Since radiosonde measurements show falling relative humidity in the upper troposphere, the T12 signal is not a relative humidity indicator.

So the paper makes the false assumption of no change in relative humidity based on little change in T12, and with increasing temperatures to 2002 (temperatures have been falling since then), the paper concludes that specific humidity is increasing.

The North American Regional Reanalysis (NARR) is a high quality dataset with a large number of radiosonde. It does not have data problem expressed with respect to the global reanalysis. This data confirms that relative humidity is falling as discussed here.
http://climatesci.org/2007/12/18/climate-metric-reality-check-3-evidence-for-a-lack-of-water-vapor-feedback-on-the-regional-scale/

There have been prominent voices saying that the developing world should not industrialise. Would you go that far? If not, why not? What evidence do you have that it is OK to industrialise?

Who has said that? I imagine you might be able to find a few people at the extreme, but I doubt it has been considered as a serious possibility. There are people who are saying that the developing world should not make the same mistakes that we did when we industrialized, but that is a different story. And, there are indeed examples of the developing world jumping technologies. For example, places have gone from no phones to cell phones, bypassing the telephone wire technology that we had.

I own a small house and I pay a surcharge on my utility bill in order to have the utility add a certain quantity of wind energy to the electricity grid.

How much will it cost to get the MUG tattoo removed?

If where you live is anything like the UK, no-one actually knows how much power is produced by wind because they don’t use bi-directional metering.

In case you didn’t know. When there is no wind, the turbines are often driven from the grid. I’ve seen wind turbines driven for days on end from the grid, using power, not generating!

There is no record of how much power is really generated, so how can they realistically charge anyone

DaveE.

“Would you please enumerate the areas of climate and the dollar amounts allotted to each of them so we can see the data that has led you to this conclusion?”

You’re asking the wrong question. Simply get familiar with the scientific literature, and you can see what people are studying. Your ignorance of the literature is causing you to draw false conclusions.

“We all know that billions have gone in to co2. So will you show us how much has gone in to these other areas you speak of?”

Do “we all” know that? From where, exactly? If you want to demand specific but irrelevant facts from people, you should first of all provide evidence for your vague claims.

Jenny Wade’s summary of the “concept of other” in Green / Affiliative Consciousness and the concept or other in the next level (beginning of second tier), Authentic Consciousness, is insightful. Color names for levels are not consistent between authors (I think Yellow and Teal are both used for this level) so I like Wade’s more descriptive labels.

So here is her take on “concept of other” from these perspectives:

Affiliative Consciousness
People are similar in kind to subject, but possess own point of view and interior life of varigated emotions
Sharing information about one’s inner life with others will lead to a consensus-based community
Differences are superficial, everyone is fundamentally equal
Differences and conflict are threatening
People need to be helped by being in close relationships

Authentic Consciousness
Very little ego-based distortion
True empathy
Respect for personal agency, diversity, and autonomy of others
Relatively free of enculturation and conformity to social expectations
Impatient with people who impede subject’s personal progress

And this level is not the end of the road, either. But, as you have mentioned, one can respect the values of other levels from this perspective without believing other values (and those who hold them) are right or are wrong in all situations. It is a viewpoint that can make for better understanding among scientists.

That correlates fairly well with what we have been seeing.

I am not saying CO2 has no effect, merely that it appears to be a minor fingerprint, not a prime mover.

Bear in mind when there is a correlation in one direction only, it is less significant than if there is something that correlates up, then down again.