There’s no predicted hotspot in the upper troposphere, and cooling of the stratosphere is now the new indicator. New paper finds “greenhouse cooling” of the stratosphere over past 52 years
A new paper published in Atmospheric Chemistry and Physics finds the stratosphere of the Northern Hemisphere cooled over the past 52 years due to the increase of greenhouse gases. The paper suggests that stratospheric cooling is a “more suitable” signal of anthropogenic global warming than trying to find a mid-troposphere hot spot (which was previously considered to be the definitive “fingerprint” of man-made global warming, but still has not been found despite millions of weather balloon and satellite observations over the past 60 years):
According to the authors,
A major open question that still remains to be answered is whether the stratosphere can be considered as a more suitable region than the troposphere to detect anthropogenic climate change signals and what can be learned from the long-term stratospheric temperature trends. Indeed, the signal-to-noise ratio in the stratosphere is, radiatively speaking, more sensitive to anthropogenic GHG forcing and less disturbed by the natural variability of water vapour and clouds when compared to the troposphere. This is because (a) the dependence of the equilibrium temperature of the stratosphere on CO2 is larger than that on tropospheric temperature, (b) the equilibrium temperature of the stratosphere depends less upon tropospheric water vapour variability and (c) the influence of cloudiness upon equilibrium temperature is more pronounced in the troposphere than in the stratosphere where
the influence decreases with height (Manabe and Weatherald,
1967). Furthermore, anthropogenic aerosols are mainly
spread within the lower troposphere (He et al., 2008), and
presumably have little effect on stratospheric temperatures.
Another open question is whether the lower stratosphere
has been cooling in the time since a reasonable global network
became available, i.e. after the International Geophysical
Year (IGY) of 1957–1958. Such a long-lasting cooling
from the 1960s until today would need to be explained.
To what extent are the cooling trends in the lower stratosphere
related to human-induced climate change? Has the
cooling been accelerating, for instance at high latitudes in
winter/spring due to ozone depletion? Has it been interrupted
by major volcanic eruptions and El Niño events (Zerefos et
al., 1992) or large climatological anomalies.
This study addresses those questions and presents a new
look at observed temperature trends over the Northern Hemisphere from the troposphere up to the lower stratosphere in a search for an early warning signal of global warming, i.e. a
cooling in the lower stratosphere relative to the warming in
the lower atmosphere.
Further, many warmists claim any source of warming including solar activity, cloud changes, ocean oscillations, etc. would cause a mid-troposphere “hot spot” and overlying cooling of the stratosphere, and would not necessarily be a signal or “fingerprint” of anthropogenic global warming.
The authors also find from 1958-1979 the lower troposphere either slightly cooled or remained unchanged, followed by significant warming 1980-2010:
From 1958 until 1979, a non-significant trend (0.06 ± 0.06 °C decade−1 for NCEP) and slightly cooling trends (−0.12 ± 0.06 °C decade−1 for RICH) are found in the lower troposphere. The second period from 1980 to the end of the records shows significant warming (0.25 ± 0.05 °C decade−1 for both NCEP and RICH). Above the tropopause a significant cooling trend is clearly seen in the lower stratosphere both in the pre-1980 period (−0.58 ± 0.17 °C decade−1 for NCEP, −0.30 ± 0.16 °C decade−1 for RICH and −0.48 ± 0.20 °C decade−1 for FU-Berlin) and the post-1980 period (−0.79 ± 0.18 °C decade−1 for NCEP, −0.66 ± 0.16 °C decade−1 for RICH and −0.82 ± 0.19 °C decade−1 for FU-Berlin).
Thus, although it appears the stratosphere may be cooling, and this could be due to increased greenhouse gases, there is still no evidence of a mid-troposphere “hot spot” predicted by climate models. The slight cooling to no change of lower tropospheric temperatures from 1958-1979 found by this paper also don’t support AGW theory since CO2 levels rose ~7% during that period.
The paper:
Atmos. Chem. Phys., 14, 7705-7720, 2014
www.atmos-chem-phys.net/14/7705/2014/
doi:10.5194/acp-14-7705-2014
C. S. Zerefos, K. Tourpali, P. Zanis, K. Eleftheratos, C. Repapis, A. Goodman, D. Wuebbles, I. S. A. Isaksen, and J. Luterbacher
Abstract
This study provides a new look at the observed and calculated long-term temperature changes from the lower troposphere to the lower stratosphere since 1958 over the Northern Hemisphere. The data sets include the NCEP/NCAR reanalysis, the Free University of Berlin (FU-Berlin) and the RICH radiosonde data sets as well as historical simulations with the CESM1-WACCM global model participating in CMIP5. The analysis is mainly based on monthly layer mean temperatures derived from geopotential height thicknesses in order to take advantage of the use of the independent FU-Berlin stratospheric data set of geopotential height data since 1957. This approach was followed to extend the records for the investigation of the stratospheric temperature trends to the earliest possible time. After removing the natural variability [it is impossible fully distinguish natural variability from anthropogenic] with an autoregressive multiple regression model our analysis shows that the period 1958–2011 can be divided into two distinct sub-periods of long-term temperature variability and trends: before and after 1980. By calculating trends for the summer time to reduce interannual variability, the two periods are as follows. From 1958 until 1979, a non-significant trend (0.06 ± 0.06 °C decade−1 for NCEP) and slightly cooling trends (−0.12 ± 0.06 °C decade−1 for RICH) are found in the lower troposphere. The second period from 1980 to the end of the records shows significant warming (0.25 ± 0.05 °C decade−1for both NCEP and RICH). Above the tropopause a significant cooling trend is clearly seen in the lower stratosphere both in the pre-1980 period (−0.58 ± 0.17 °C decade−1 for NCEP, −0.30 ± 0.16 °C decade−1 for RICH and −0.48 ± 0.20 °C decade−1 for FU-Berlin) and the post-1980 period (−0.79 ± 0.18 °C decade−1 for NCEP, −0.66 ± 0.16 °C decade−1 for RICH and −0.82 ± 0.19 °C decade−1 for FU-Berlin). The cooling in the lower stratosphere persists throughout the year from the tropics up to 60° N. At polar latitudes competing dynamical and radiative processes reduce the statistical significance of these trends. Model results are in line with reanalysis and the observations, indicating a persistent cooling (−0.33 °C decade−1) in the lower stratosphere during summer before and after 1980; a feature that is also seen throughout the year. However, the lower stratosphere CESM1-WACCM modelled trends are generally lower than reanalysis and the observations. The contrasting effects of ozone depletion at polar latitudes in winter/spring and the anticipated strengthening of the Brewer–Dobson circulation from man-made global warming at polar latitudes are discussed. Our results provide additional evidence for an early greenhouse cooling signal in the lower stratosphere before 1980, which appears well in advance relative to the tropospheric [assumed] greenhouse warming signal. The suitability of early warning signals in the stratosphere relative to the troposphere is supported by the fact that the stratosphere is less sensitive to changes due to cloudiness, humidity and man-made aerosols. Our analysis also indicates that the relative contribution of the lower stratosphere versus the upper troposphere low-frequency variability is important for understanding the added value of the long-term tropopause variability related to human-induced global warming.
(this post via the HockeySchtick)
RELATED:
About that missing hot spot in the upper troposphere
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“The records of the 14C content of the atmosphere and oceans contain a remarkable array of information about Earth history. Produced by cosmic rays in the upper atmosphere, 14CO2 rapidly mixes throughout the troposphere and exchanges with the reactive carbon reservoirs of the oceans and biosphere, where it decays. For the past 11,000 years, fluctuations in the atmospheric 14C have been largely produced by changes in the solar magnetic field. Many researchers believe that carbon cycle changes, tied to deep ocean circulation changes are a significant cause of atmospheric 14C fluctuations between 11,000 and 15,000 years before present. On longer time scales, changes in the Earth’s magnetic field intensity impact the 14C content of the atmosphere, producing positive 14C anomalies during intervals of weaker geomagnetic field.”
http://radiocarbon.ldeo.columbia.edu/research/radiocarbon.htm
Dr. Strangelove says: “Stratospheric cooling should not be hyped as “fingerprint” of AGW especially the catastrophic kind. The cooling is predicted by greenhouse effect theory. Who’s denying greenhouse effect? ”
Careful Doc, you are confounding two different things.
No one is questioning the radiative properties of CO2 . That does not imply acceptance of any and all of the various things that allegedly “predicted” by “greenhouse theory” ( which is an ever mutable hypothesis, not a theory).
The paper cited here is methodical mess. It claims to remove natural variability, like volcanoes, but clearly does not because the disruption of the two events is still clearly present after their data mangling.
This post 1980 period, which still contains the volcano induced cooling, is then fitted with a linear model and voila! : proof of increased AGW.
The literature they cite , including Randal et al 2009, clearly identifies the step nature of the changes in this period yet they try to regress it using only AOD which can never match the step change since it is at the same level a few years after the events.
They quite knowingly regress against something that does not fit. This guarantees that the drop will remain in the data they claim to have adjusted for natural effects.
If they have failed to account for the nature of the change as described in their own references, it is hard to see this as anything but deliberate malfeasance.
OK, perhaps it’s best not to infer motivation. It may be better to say deliberate malfeasance or gross incompetence.
“Cosmic rays enter the earth’s atmosphere in large numbers every day. For example, every person is hit by about half a million cosmic rays every hour. It is not uncommon for a cosmic ray to collide with an atom in the atmosphere, creating a secondary cosmic ray in the form of an energetic neutron, and for these energetic neutrons to collide with nitrogen atoms. When the neutron collides, a nitrogen-14 (seven protons, seven neutrons) atom turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons). Carbon-14 is radioactive, with a half-life of about 5,700 years.”
http://s.hswstatic.com/gif/carbon-14.gif
“So you can imagine it came as a shock when, just yesterday, nature released a paper showing a big, short-lived spike in carbon-14 levels way back in the 8th Century! By looking at the tree rings of ancient Japanese Cedars, you can see a rise in the concentration of carbon-14 that starts in the 770s, peaks in the 780s and then falls off.
What does this correspond to, in terms of creating this carbon-14? Well, there were no nearby supernovae that happened at that time, so that’s out. There’s no evidence of an unusually large solar flare or any other bizarre solar activity, so that can’t be the culprit, either. What this appears to correspond to, at least at this preliminary stage, is an increase in cosmic rays.”
http://scienceblogs.com/startswithabang/files/2012/06/nature11123-f1.jpeg
http://scienceblogs.com/startswithabang/2012/06/04/the-cosmic-story-of-carbon-14/
In reply to:
Matthew R Marler says:
August 4, 2014 at 9:45 am
John Who: So, is it “warming causes cooling”
or “cooling causes warming”?
CO2 causes surface and troposphere warming (that’s the theory), but causes stratospheric cooling.
William:
The warmists have ignored other explanations for the cooling of the stratosphere and have ignored observations that support the assertion that the majority of the warming in the last 50 years (more than 90%) is due to solar magnetic cycle modulation of planetary clouds, rather than CO2. As low level clouds reflect short wave radiation up into space and as a portion of the short wave radiation is absorbed in the stratosphere by ozone, a reduction in low planetary clouds will cause surface warming and will cause the stratosphere to cool.
A reduction in low level clouds as the explanation for the surface warming in the last 50 years explains why the increase in warming suddenly stopped 17 years, 10 months ago. The mechanism that caused there to be a reduction in low level clouds primarily at high latitudes had peaked.
A reduction in low level clouds caused by solar magnetic cycle changes rather than the increase in atmospheric CO2 explains the cyclic warming and cooling of the planet in the paleo record (both hemispheres) with warming and cooling occurring primarily at high latitudes (i.e. Same pattern of warming that we observed in the last 50 years). The solar magnetic cycle modulation of planetary clouds explains why the warm periods in the paleo record occur when the solar magnetic cycle is high and the cold periods occur when the solar magnetic cycle is low.
As CO2 is more or less evenly distributed in the atmosphere the potential for warming due to the increase in atmospheric CO2 should be the roughly the same for all latitudes. As the amount of forcing produced by the increase in CO2 is directly proportional to the amount of long wave radiation that is emitted to space prior to the increase in atmospheric CO2, all else being the same the most amount of warming that should occur due to the increase in atmospheric CO2 should have occurred in the tropics where there is the most amount of long wave radiation emitted to space prior to the increase in CO2 and where there is ample water to amplify the CO2 forcing change.
The fact that there is almost no tropical region warming observed supports the observation/assertion that there is no tropical tropospheric warming at roughly 8km. The CO2 theory predicts that high altitudes in the atmosphere will warm more than lower regions of the atmosphere due to the increase in atmospheric CO2 due to two reasons.
Due to the lapse rate (the amount of water vapour in the atmosphere changes with altitude due to the cooling of the atmosphere with altitude) there is comparatively more relative water vapour in the atmosphere at lower regions in the atmosphere than higher regions in the atmosphere. The greenhouse gases absorb and emitted specific bands frequency bands. As the emission bands of water vapour and CO2 overlap and due to the number of CO2 molecules per unit volume prior to the increase in atmospheric CO2, the majority of the warming due to the increase in atmospheric CO2 was predicted to occur at higher regions of the troposphere where there is less water compared to CO2 and where there were less CO2 molecules per unit volume prior to the increase in CO2.
If the CO2 predicted high altitude CO2 warming had occur, the warming of the atmosphere by the increase in CO2 would have enabled the higher altitude regions of the atmosphere to hold more water vapour which would then have cause the water vapour amplification of the CO2 forcing to occur. The predicted water vapour amplification of the CO2 forcing change is not due to an increase in surface evaporation but rather due to the predicted higher altitude CO2 warming.
The warming of the higher altitudes in the troposphere (roughly at 8km in the tropical regions) by the increase in CO2 then per the CO2 theory warms the surface of the planet by long wave radiation.
The observation that there is no tropospheric hot spot at 8km is supported by the observation that there is almost no long term observed warming of the tropical region. i.e. The warmists are ignoring connected logic. Their theory predicts (1) tropical tropospheric warming at 8km which in turn should cause (2) tropical region warming. (1) is not observed which supports the assertion/observation that (2) did not occur.
Comments:
The following are papers that explains the latitude pattern of warming does not match that predicted by the CO2 theory and the predicted tropical troposphere warming at 8km did not occur.
http://arxiv.org/ftp/arxiv/papers/0809/0809.0581.pdf
Limits on CO2 Climate Forcing from Recent Temperature Data of Earth
3.2 Latitude effect
We have examined the temperature anomalies at the various latitudes enumerated above for three data sets: HadCRUT3v, and MSU_LT from UAH and from RSS. All show similar behavior. However, as explained above, we only present the results from MSU_LT_UAH. Figure 2 shows the UAH_LT anomalies for NoExtropics, Tropics, SoExtropics and Global. The average trends over the range 1979-2007 are 0.28, 0.08, 0.06 and 0.14 ºK/decade respectively. If the climate forcing were only from CO2 one would expect from property #2 (William: CO2 is after a lag of 12 months evenly distributed in the atmosphere) a small variation with latitude. However, it is noted that NoExtropics is 2 times that of the global and 4 times that of the Tropics. Thus one concludes that the climate forcing in the NoExtropics includes more than CO2 forcing. These non-CO2 effects include: land use [Peilke et al. 2007]; industrialization [McKitrick and Michaels (2007), Kalnay and Cai (2003), DeLaat and Maurellis (2006)]; high natural variability, and daily nocturnal effects [Walters et al. (2007)].
http://wattsupwiththat.files.wordpress.com/2012/12/ipcc-ar5draft-fig-1-4.gif
http://icecap.us/images/uploads/DOUGLASPAPER.pdf
A comparison of tropical temperature trends with model predictions
The following is the Greenland Ice Sheet temperature Vs atmospheric CO2 for the last 11,000 years, determined by the analysis of ice cores. The analysis shows the Greenland Ice sheet gradually becomes colder and experiences the Dansgaard-Oeschger (D-O) warming and cooling cycles (1450 year cycle plus or minus 500 years) and atmospheric CO2 gradually increases.
Greenland ice temperature, last 11,000 years determined from ice core analysis, Richard Alley’s paper.
http://www.climate4you.com/images/GISP2%20TemperatureSince10700%20BP%20with%20CO2%20from%20EPICA%20DomeC.gif
Thanks, Tom T. I have a rough idea of how the additional cooling happens now.
Browsing online, I read about a NEGATIVE greenhouse effect on Saturn’s moon Titan.
Using the greenhouse model here
http://www.geo.utexas.edu/courses/387H/Lectures/chap2.pdf
I did a few simple calculations.
When the atmosphere is transparent to incoming radiation from the sun and opaque to outgoing radiation from the planet, you get a positive greenhouse effect- as happens with CO2 and H20.
When the atmosphere is opaque to incoming radiation from the sun and transparent to outgoing radiation to the planet you get a negative greenhouse effect, as happens in some frequencies on Titan- and I suppose, with O3 on Earth..
When the atmosphere is opaque to both incoming radiation from the sun and outgoing radiation from the earth you get a zero greenhouse effect- I suppose this happens to some extent with clouds.
Putting it all together, with CO2 alone, temperatures decrease the higher in the atmosphere you get. With O3 alone, temperatures decrease the lower in the atmosphere you get. The stratosphere temperature increase the higher in the atmosphere you get, is due to a combination of CO2s temperature decline effect- postive greenhouse, , and O3’s temperature increase effect-negative greenhouse. Add the CO2 cooling vector to the O3 warming vector, and the O3 effect overwhelms the CO2 efffect in our stratosphere.
If CO2 increases and O3 remains the same, we add the two vectors and get a very slight
lesser net O3 temperature increase with height.
.
William Astley
http://www.climate4you.com/images/NOAA%20ESRL%20AtmospericRelativeHumidity%20GlobalMonthlyTempSince1948%20With37monthRunningAverage.gif
As far as I can tell from the data…stratospheric cooling effectively ‘paused’ in 1994…so leaving twenty years with no statistically significant warming, whilst CO2 increased substantially.
William Astley says:
August 5, 2014 at 4:53 am
As low level clouds reflect short wave radiation up into space and as a portion of the short wave radiation is absorbed in the stratosphere by ozone, a reduction in low planetary clouds will cause surface warming and will cause the stratosphere to cool.
The short wave radiation that could be absorbed by O3 (UV A & B) has already been absorbed on the first pass and water vapor and clouds are also strong absorbers in that wavelength range so there will be no back scattered light to be absorbed so your proposed mechanism doesn’t happen.
Bill H,
I’m going to go with willfully obtuse to describe your last post. No one has that poor of reading comprehension. At this point you are just lying. Your entire post is a sting of lies by context where you assert that things I said about one subject were said about another. Thank you for proving my point forms of lying specifically lying by context. You really dont think that lying by context is lying do you?
#1 I have never said that increasing CO2 doesn’t cool the stratosphere. I have questioned why and its claimed direct relationship to anthropogenic global warming.
#2 I never said that Manabe and Wetherall was junk. I said that that Zerofos et. al. Is junk. At this point you are lying.
#3 Manabe and Wetherall does show stratospheric cooling due to CO2 but they do not attribute the physical cause. All they say about it is “The larger the mixing ratio of carbon dioxide, the colder is the equilibrium temperature of the stratosphere”. No where in the paper do they claim that it is due to a decrease in upwelling long wave radiation. I implicitly challenged you to provide a quote from the paper saying as much. Now I’m directly challenging you to provide a quote that supports your assertion that Manabe and Wetherall claims ““long wave radiation would increasingly be absorbed in the troposphere with increasing CO2 leading to less long wave radiation reaching the stratosphere”.
#4 Grab a dictionary and read the definition of misanthropy.
#5 You are back tracking and now trying to argue that CO2 causes cooling in the stratosphere while ignoring that your assertion was that this was because “long wave radiation would increasingly be absorbed in the troposphere with increasing CO2 leading to less long wave radiation reaching the stratosphere”. Again I challenge you to support that assertion.
#6 In the issue of radiation and absorption you are looking monocularlly. Very little long wave radiation reaches the stratosphere. CO2 in the stratosphere absorbs and radiates the lions share of its energy in the stratosphere through both radiation and conduction from O3 which is excited by shortwave radiation. Bing mostly transparent to short wave radiation CO2 in the stratosphere does not significantly increase the stratospheres ability to absorb energy but it does significantly increase its ability to radiate radiate the energy absorbed by the O3 in the stratosphere.
I await what other lies of context you will make next.
I have another good anology.
Saying that stratospheric cooling and anthropogenic global warming are physically related is like saying tat pissing and drowning a physically related. Same cause, water, but totally different process.
Reblogged this on Public Secrets and commented:
An atmospheric “hotspot” was supposed to be one of the indicators of anthropogenic global warming. But, said hot spot never appeared. Now we see the stratosphere has been cooling, which a new paper suggests is a better signal of… global warming. Naturally. Click the link to read more.
Climate Weenie says, August 4, 2014 at 9:38 am:
“(…) the MSU data sets seem to indicate the continued cooling.
http://climatewatcher.webs.com/HotSpot_Pause.png
The effect of stratospheric cooling is to slightly reduce RF at the tropopause.”
The MSU data sets seem to indicate no such thing. In fact, they show very clearly that there hasn’t been ANY lower stratospheric cooling at all for the last 20 years (since 1994, after the effects of the Pinatubo stratospheric aerosols – destroying tons of O3 – had finally dissipated):
ftp://ftp.ssmi.com/msu/graphics/tls/plots/rss_ts_channel_tls_global_land_and_sea_v03_3.png
During that same time, about a third of the alleged rise in atmospheric CO2 since pre-industrial times occurred (358-398 ppm).
“Stratospheric cooling is a direct result of CO2 calculated from radiative transfer models alone ( the ones we have confidence in ).”
In other words, your ‘radiative transfer models’ (the ones you have such confidence in) failed miserably.
Climate Weenie says, August 4, 2014 at 10:27 am:
“So, a radiative model of an increased CO2 atmosphere will yield reduced net longwave at the troposphere.
That being the case, the layers above experience less energy.
Which part is a myth? and why?”
The problem of this radiative model of yours is that total OLR from the tropopause hasn’t descreased over the last three decades, as the theory apparently postulates. It has rather increased in step with tropospheric temperatures, as the real world postulates.
William Astley: The warmists have ignored other explanations for the cooling of the stratosphere and have ignored observations that support the assertion that the majority of the warming in the last 50 years (more than 90%) is due to solar magnetic cycle modulation of planetary clouds, rather than CO2. As low level clouds reflect short wave radiation up into space and as a portion of the short wave radiation is absorbed in the stratosphere by ozone, a reduction in low planetary clouds will cause surface warming and will cause the stratosphere to cool.
I agree that the warmist case is full of holes, and warmists dismiss too casually or don’t consider at all other explanations for a variety of changes of the last centuries and decades. My post was directed toward a particular rather shallow comment.
gregfreemyer seems to be closest to what is going on.
This note is to isolate the basic physics from the additional complications of water and O3.
Gas molecules have discrete energy levels. If a gas molecule is excited it will after a sufficient period of time emit the energy and lose it. The rate of this process is given by the Einstein coefficient of radiation, in a time on the order of h-bar/delta energy. Excitation can occur from either absorption of a photon or from a collision with another molecule. If the molecule is not subsequently excited, it will eventually radiate its energy until it reaches a state consistent with absolute zero.
At issue is the balance between excitation and deexcitation by radiation and collision processes where there is at best “local thermodynamic equilibrium” even at low altitudes.
At lower altitudes where density and temperatures are higher, collisions deexcitation is relatively more likely than direct radiation, so absorbed radiation gets dumped into the kinetic heat of the neighboring molecules. But at higher altitudes where density and temperatures are lower, radiation of energy is relatively more likely. Left alone long enough, a molecule can radiate its heat thereby reducing the temperature of the local ensemble.
The statement is wrong that “Greenhouse gases (CO2, O3, CFC) absorb infra-red radiation from the surface of the Earth and trap the heat in the troposphere” . Gas molecules don’t trap heat.
It remains to be seen if CO2 might cause a warming in the troposphere under the right conditions. But I agree with Mosher that its primary fingerprint is stratospheric cooling.
ren,
Are those graphs from NOAA for global relative humidity?
300 mb relative humidity has dropped 10% globally since 1950.
600 mb relative humidity dropped 5% from 1950-82 then was steady at the lower level.
Surface relative humidity has not changed that much.
At the very least, this should have resulted in much less cirrus/high level cloudiness.
During warming at the surface, this would be consistent with Lindzens Iris theory, which claims that the earth clouds are like an iris is to the eye. Your iris contracts to allow less light in, when the light is bright.
Lindzen says that the earths surface warming has a negative feedback from decreasing cirrus clouds that allow more heat to radiate out to space.
Only problem here……………. is that these dropping 600 mb rh values were happening during modest global cooling in the 50’s-70’s and continued.
All of the drop at 600 mb was during that period prior to 1982.
We have increased low level moisture and one or the sources that is underestimated is the increase in evapo(transpiration) from the increase in plant growth that has resulted from atmospheric fertilization from increasing CO2.
This lowers the lifting condensation level and base of clouds. Cloud height has been measured to to decrease during the last decade.
Clouds that radiate from a lower level(and warmer temperature) are more effectively radiators(to space) vs high clouds that trap more heat.
Interesting comments A. Ames. But you may be missing the point.
At the top of this page, it says “The paper suggests that stratospheric cooling is a “more suitable” signal of anthropogenic global warming than trying to find a mid-troposphere hot spot (which was previously considered to be the definitive “fingerprint” of man-made global warming)”
Steven Mosher then said: “Stratospheric cooling is the better fingerprint.”
Mosher never said stratospheric cooling of the stratosphere is a fingerprint of CO2. His comment has to be taken in the context of the subject of the post – we can take it that he meant the better fingerprint of the Enhanced Greenhouse Effect.
But the Enhanced Greenhouse Effect claims that adding CO2 to the atmosphere will cause warming of the surface by radiative physics. This is amplified to its more alarming variant … that the warming will be catastrophic.
So we have that ambiguous language once again. Stratospheric cooling is a better finger print for change of CO2 (as you say). But it does not follow that it is the better fingerprint for the Enhanced Greenhouse Effect.
The best fingerprint for the Enhanced Greenhouse Effect is observation of the physical changes as predicted: that would be the hotspot (cooling stratosphere or otherwise). Santer tried to find evidence for vertical amplification (as he called it) and failed.
Conclusion: this is a dead parrot.
Kristian says:
August 5, 2014 at 12:57 pm
Climate Weenie says, August 4, 2014 at 9:38 am:
“(…) the MSU data sets seem to indicate the continued cooling.
http://climatewatcher.webs.com/HotSpot_Pause.png
The effect of stratospheric cooling is to slightly reduce RF at the tropopause.”
The MSU data sets seem to indicate no such thing. In fact, they show very clearly that there hasn’t been ANY lower stratospheric cooling at all for the last 20 years (since 1994, after the effects of the Pinatubo stratospheric aerosols – destroying tons of O3 – had finally dissipated):
Nice ‘bait and switch’, the subtle change from ‘stratospheric cooling’ to ‘lower stratospheric cooling’! Whereas the expected effect of CO2 is in the upper stratosphere not the lower where O3 is expected to be dominant.
***
Phil. says:
August 5, 2014 at 7:34 pm
Nice ‘bait and switch’, the subtle change from ‘stratospheric cooling’ to ‘lower stratospheric cooling’! Whereas the expected effect of CO2 is in the upper stratosphere not the lower where O3 is expected to be dominant.
***
Huh? CO2’s dominant effect is in the upper troposphere near the tropopause where its characteristic band can freely radiate upward.
Stephen Wilde says:
August 4, 2014 at 12:32 pm
“The stratosphere cooled whilst the sun was active then stopped cooling around 2000 and may now be warming.
Since the change in trend coincided with the decline in solar activity it seems that an active sun cools the stratosphere and warms the troposphere whilst a quiet sun does the opposite.”
That is right Stephen, solar activity dominates the cooling and warming of the stratosphere, and for that matter the troposphere via its effect on cloud formation, surface pressure and especially the Polar Jets:
http://wattsupwiththat.com/2013/01/31/ozone-depletion-trumps-greenhouse-gas-increase-in-jet-stream-shift/
It is all linked to the sites of formation and destruction of ozone that is linked to the level and wavelength of solar UV as the cycles reach peak and decline as well as between solar cycles of differing amplitude. When the Sun is active ozone is destroyed by NO2, hence the famous scare over ozone holes during the late 20th century. Since ozone absorbs LWR emitted from the surface and UV from the Sun its reduction in level in the upper stratosphere causes stratospheric cooling. However the ozone that is formed is found in the lower stratosphere and upper troposphere and likewise absobs LWR and UV radiation warming the upper the troposphere so having an effect on cloud formation. When the Sun is quiet, as now, the reduction in the destruction of ozone from a less active solar wind increases the ozone level in the upper stratosphere and the stratosphere warms.
http://www.space.dtu.dk/upload/institutter/space/forskning/06_projekter/isac/wp501b.pdf
Solar activity Ozone Mes/Strat Ozone Strat /Trop Warming or/Cooling Jets
>45km Stratopause <45km Stratopause Mes/Strat/Trop
High Decreased Increased Cooling/Warming Zonal
Low Increased Decreased Warming/Cooling Meridional
The warming role of CO2 is minimal as it has a low heat capcity compared to ozone with the evidence showing that it has the effect of cooling the stratosphere and thermosphere:
CO2 acts together with NO2 as a huge cooling mechanism for Earth's thermosphere
http://hockeyschtick.blogspot.com/2014/03/new-paper-finds-no-effect-of.html
So stratospheric warming and cooling is indeed a good fingerprint of climate change but not of CAGW from anthropgenic emissions of CO2 rather of natural variation due to solar activity. These activities are well stated in articles by Earl Happ:
http://wattsupwiththat.com/author/erlhapp/
http://climatechange1.wordpress.com/2013/08/11/the-turning-point/
Support for the ozone effect is given in a study by Polvani and Solomon:
http://www.agu.org/pubs/crossref/2012/2012JD017719.shtml
I want to sincerely thank all the contributors/commenters on this thread. It has been very informative on my part. I have read (closely) every comment and have just completed a second round of reading the comments even more closely. I will do so a third time as this is most interesting and the discussion is in what my understanding of what the scientific principle should be all about.
Again, thanks to all.