From The Hockey Shtick, word of a new paper that supports Miskolczi’s theory of saturated greenhouse effect. We’ve seen this before, in the form of this graph.
In 2006, Willis Eschenbach posted this graph on Climate Audit showing the logarithmic net downward IR forcing effect of carbon dioxide relative to atmospheric concentration:
The flatter portion of the graph gradually smooths out, as the effect of CO2 forcing becomes saturated with increased concentration. And this graphic of his shows carbon dioxide’s contribution to the whole greenhouse effect:
What’s more, in this new paper there appears to be some evidence for a negative climate feedback, in the form of slightly lowered relative humidity trend, which makes climate sensitivity lower. Relative humidity (RH) is the ratio of the actual amount of water vapor in the air to the amount it could hold when saturated expressed as a percentage OR the ratio of the actual vapor pressure to the saturation vapor pressure expressed as a percentage. The amount of water vapor the air can hold increases with temperature. Relative humidity therefore decreases with increasing temperature if the actual amount of water vapor stays the same. While the study found a slight increase in specific humidity (the mass of water vapor per unit mass of air), relative humidity (near the surface, 2 meter measurement) decreased by 0.5% per decade, resulting in an overall slightly drier atmosphere.
If a positive water vapor feedback response existed in the climate system, you’d expect both the specific and relative humidity to increase with time. It didn’t. This ends up putting the kibosh on the idea of tipping points, and a lack of positive water vapor feedback pretty much takes all the scare out of CO2 induced climate change.
Of note is the issue with station inhomogeneity which apparently had been masking the signal in earlier studies. This study looked at stations individually to determining where such inhomogeneity existed. Here’s an example in figure 3 of their paper:
From THS:
A paper published today in the Journal of Climate finds that relative humidity has been decreasing 0.5% per decade across North America during the 62 year period of observations from 1948-2010.
Computer models of AGW show positive feedback from water vapor by incorrectly assuming that relative humidity remains constant with warming while specific humidity increases. The Miskolczi theory of a ‘saturated greenhouse effect’ instead predicts relative humidity will decrease to offset an increase in specific humidity, as has just been demonstrated by observations in this paper. The consequence of the Miskolczi theory is that additions of ‘greenhouse gases’ such as CO2 to the atmosphere will not lead to an increase in the ‘greenhouse effect’ or increase in global temperature.
Journal of Climate 2012 ; e-View
doi: http://dx.doi.org/10.1175/JCLI-D-11-00003.1
Surface Water Vapor Pressure and Temperature Trends in North America during 1948-2010
V. Isaac and W. A. van Wijngaarden*
Physics Dept., Petrie Bldg., York University, 4700 Keele St., Toronto, ON Canada, M3J 1P3; e-mail: wlaser@yorku.ca
Abstract
Over 1/4 billion hourly values of temperature and relative humidity observed at 309 stations located across North America during 1948-2010 were studied. The water vapor pressure was determined and seasonal averages were computed. Data were first examined for inhomogeneities using a statistical test to determine whether the data was fit better to a straight line or a straight line plus an abrupt step which may arise from changes in instruments and/or procedure. Trends were then found for data not having discontinuities. Statistically significant warming trends affecting the Midwestern U.S., Canadian prairies and the western Arctic are evident in winter and to a lesser extent in spring while statistically significant increases in water vapor pressure occur primarily in summer for some stations in the eastern half of the U.S. The temperature (water vapor pressure) trends averaged over all stations were 0.30 (0.07), 0.24 (0.06), 0.13 (0.11), 0.11 (0.07) C/decade (hPa/decade) in the winter, spring, summer and autumn seasons, respectively. The averages of these seasonal trends are 0.20 C/decade and 0.07 hPa/decade which correspond to a specific humidity increase of 0.04 g/kg per decade and a relative humidity reduction of 0.5%/decade.
The full paper from the Journal of Climate can be viewed at this link.
The one critique that I have of the graphs presented above is the use of a linear instead of logarithmic scale on the carbon dioxide concentration factor. Of course David Archibald, in his “The Fate of All Carbon” article indicates that there may not be enough economically recoverable, combustible carbon remaining on Earth to ever bring the carbon dioxide concentration up to 560 ppm–just double the nominal pre-industrial concentration level.
As late as three years ago, many otherwise intelligent people in positions of power believed that there was an urgent need to cut carbon dioxide emissions by eighty percent before 2050 to prevent the destruction of our environment. It looks like resource depletion will eventually do this anyway. I believe we should now be preparing for the gradual loss of fossil or abiotic carbon as a source of energy while we still may have time to make a gentle transition, rather than worrying about a non-existent, super-accelerated, greenhouse effect.
The story as I understand it so far:
(and is only active in one moderate sized band in the overall radiation spectrum). A tiny increase of radiative temperature at the Earth’s surface can compensate for a far larger decrease of radiative temperature at 20 km. One needs to make the CO_2 at the tropopause many degrees colder, on average, everywhere, to make the surface one degree warmer, on average, everywhere and just the shift from DALR to WALR — which moves the lapse down and warms the tropopause utterly confounds CO_2-based increases; the feedback from more water in the atmosphere due to CO_2 based warming should strictly be negative, warming the CO_2 at the very place where it is radiating away its heat.
CO2 main absorption spectral lines are already stopping nearly all the LWIR in those bands from freely escaping the atmosphere.
However, there is spectral broadening caused by pressure and Doppler shift. It is these lobes that are now increasingly absorbing IR giving the presumably log effect.
I don’t think this is the major factor, although I could be mistaken. Pressure broadening depends on absolute pressure, not partial pressure (it’s related to the mean free time between collisions, and the collisions don’t have to be with other CO_2 molecules but with any molecules), and that isn’t really changing at all. Doppler broadening depends on temperature, so this is one degree of feedback removed from the increase in the GHE caused by increased concentration, a second order (but positive feedback) effect.
My understanding is that the increase comes strictly from raising the tropopause — or rather, raising the height above the ground where the atmosphere becomes sufficiently optically transparent to allow radiation from CO_2 molecules to actually escape to space. The higher the cooler, the cooler the greater the net GHE. There is considerable evidence for this — one of the reasons for El Nino warming is that it is a breathing mode atmospheric oscillation that lifts the tropopause and hence actually does increase greenhouse trapping, allowing for positive feedback amplification of the warming itself, for example.
The problem with this is that the tropopause isn’t like a CO_2-trapping plastic balloon between the troposphere and the stratosphere, so that taking partial pressure/net concentration of CO_2 inside the balloon from 280 ppm (0.03%) to 340 ppm (0.03% — ooo, looks like I need more significant figures, don’t I) isn’t going to blow the balloon up by, well, 0.006%, and if it did, the radiation would be cooled by an additional amount determined by the DALR (in the troposphere) of ~9K/km. If we assume the troposphere is a generous 20 km thick, and the tropopause went up linearly with CO_2 concentration (most unlikely), then the entire increase since the beginning of the industrial era would have raised the mean temperature at the tropopause by 0.01 K.
It’s not quite this simple, of course — the direct effect is so low that the second order effects might be comparable. However, those effects are far, far more powerfully modulated by things other than CO_2 concentration. The decadal oscillations move the troposphere up or down by gross amounts compared to the meter or so predicted by a simple linear model. The location of the tropopause and the stratosphere itself is highly multifactorial — in a way it is self-consistently determined just where the CO_2 does indeed start to radiate, producing a cool layer followed by a lateral transport layer in between the warm ground and the hot thermosphere. I have yet to hear a convincing argument (with actual empirical support) for why the GHE should be significantly modulated by further increases in atmospheric CO_2 once saturation has occurred. If the speculations in the top article are correct — and there is reason to think that they are, it isn’t some sort of violation of the laws of physics to think that they might be — the evidence suggests that macroscopic modulators of the Earth’s atmospheric dynamics are far more important for determining the location of the tropopause and optical radiation zone than concentration.
One can photograph the GHE in action in the form of LWIR spectra at the top of the atmosphere. However, we do not have anything like a sufficient baseline of data to identify specific changes wrought by increased CO_2. Everything is confounded by far larger secular oscillations and negative feedbacks throughout the system.
Note well that one needs large changes in the tropopause to significantly change the ground temperature. The CO_2 band is already “cold”, and the rate of power loss per square meter goes like
This is why I think that it is very, very wrong to try to explain the GHE in terms of “upwelling” or “downwelling” radiation. This is a false heuristic from the beginning. All that matters is the top of atmosphere spectrum, selective spigots on the outflowing radiation, the height/temperature where the atmosphere becomes transparent (enough) to it, and the lapse rate that self-consistently establishes the relation between height and temperature, the location of the tropopause, and so on. One cannot separate out an imagined individual variable in the multivariate nonlinear system like “downwelling radiation”, assert that it is responsible for “warming” the surface, and then solve a detailed balance equation for the surface pretending that what happens there somehow depends on what’s going on at 20,000 meters via a direct process with no complexity.
I think that there is very probably an extremely simple mathematical statement of the GHE that eliminates all of the arguable detail and permits one to directly numerically focus on a semi-empirical heuristic. If I live long enough and every have free time again, maybe I’ll look for it.
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Robert Brown says:
February 13, 2012 at 9:03 am
“Doppler broadening depends on temperature, so this is one degree of feedback removed from the increase in the GHE caused by increased concentration, a second order (but positive feedback) effect.”
There is also a potential negative feedback effect in the fact that a broader distribution is able to radiate energy away at lower wavenumber. That means the surface temperature does not have to be as high to balance the energy radiating away from the planet.
And, there is another negative feedback from higher concentration, and that is that less energy needs to radiate away from higher energy emitters like CH4 in order to achieve balance, so again, the surface temperature does not have to be as high to balance the energy radiating away from the planet.
There is also a potential negative feedback effect in the fact that a broader distribution is able to radiate energy away at lower wavenumber. That means the surface temperature does not have to be as high to balance the energy radiating away from the planet.
And, there is another negative feedback from higher concentration, and that is that less energy needs to radiate away from higher energy emitters like CH4 in order to achieve balance, so again, the surface temperature does not have to be as high to balance the energy radiating away from the planet.
Yeah, I admit to being frankly puzzled as to how one can believably estimate — not even compute, just estimate — the straight up GHE warming expected in response to CO_2. I’m really puzzled by the assertion that feedback from non-CO_2 channels will produce 3-5x as much warming as the CO_2 alone. This strong positive feedback could hardly fail to leave its mark in the dynamic responses to non-CO_2 related thermal fluctuations, characterized by extremely rapid warming, very slow cooling not just globally but locally. Yet global temperatures flow along according to seasonal norms, and seem if anything remarkably stable given the complexity of the climate system.
But I think the really big error is that they are probably getting the sign wrong for the feedback from water vapor, asserting that it is the big positive when it is really very likely a weak negative (or at worst, weak positive). The bottom line is that the data from the thermometric era alone (the last 150-160 years) suffices to solidly reject the more extreme of the positive feedback hypotheses. The “Catastrophic Window” is steadily narrowing.
rgb
Robert Brown says:
February 13, 2012 at 10:36 am
I’m with you all the way, there.
“I’m really puzzled by the assertion that feedback from non-CO_2 channels will produce 3-5x as much warming as the CO_2 alone.”
Confirmation bias. There was warming, and they were sure they had the culprit, so they misapplied the logic of a pulp fiction detective:
Only if you have a full set of potentialities, of course. They’d have been better advised to take heed of another quote from the same source:
Sorry, I found this in my notes. Just want to include the reference. GK
https://www.scientificamerican.com/article.cfm?id=planning-picnic-in-warming-world-satellite-forecasts-more-rain&posted=1#comments
@jjthoms…
Regarding your comment on backradiation recorded with pyrgeometers, I have been measuring downward radiation during nighttime and daytime and I can assure you that it is not thermal radiation emitted by the atmosphere. Any dome made with polished aluminum produces the same results. I have found serious deffects on the experiment you refered at
http://www.slf.ch/ueber/mitarbeiter/homepages/marty/publications/Marty2003_IPASRCII_JGR.pdf
In brief, the authors do not specify the conditions of the cloudiness. A cloud cover can produce biased results. Any species of clouds damages the results. The objective of the experiment that you referred was not to measure accurately downward longwave radiation, but the efficiency of pyrgeometers. From their results and my results, the sole conclusion is that pyrgeometers are not useful to measure downward radiation.