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)
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Apparently evidence of stratospheric cooling is evidence the stratosphere has cooled, no more, no less, because here on planet Earth even the IPCC’s so-called “global average temperature” has been flat for nearly two decades.
But please keep us informed of stratospheric temperature trends, it’s a nice break from Middle East news.
gregfreemyer,
The dominate mode of energy transfer in the stratosphere between CO2 and O3 its molecular transfer that dominates. O3 molecules excited by short wave radiation from the sun collide with CO2. The CO2 then radiates this absorbed kinetic energy out to space.
In the stratosphere CO2 just serves as a radiator for O3.
It is revealing how messy their reanalysis/model data with “natural” variations removed looks compared to straightforward low-pass filter of satellite observations.
Nowhere in this study to do they actually look at real data, they use model output ( funny ) , ‘reanalysis’ output, and “homogenised” balloon data.
Despite there being very good global coverage for their second period of study ( 1980 on ) they don’t actually look at it.
It would seem rather obvious if they did, that they convoluted processing is degrading the data, casting serious doubt on the underlying “trend”. they are fitting.
http://climategrog.wordpress.com/?attachment_id=902
This mindless obsession with fitting linear models to data that has nothing linear about it is one of the biggest impediments to progress in this field.
Climate variables are not linear progession on any time scale.
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.
For AGW to be viable the stratosphere must cool just as the GAST must rise.
http://www.realclimate.org/?comments_popup=2019Note
John Henriksen asks:
“what would FALSIFY [linking CO2 to ‘warming’]?”
Schmidt answers:
”that the stratosphere is not cooling as expected (this is a cleaner test than the surface temperatures because there are less extraneous factors)”
The stratosphere hasn’t been cooling (significantly wrt model projections) in over a decade, another AGW fingerprint just taking a hiatus I reckon.
http://www.acd.ucar.edu/Research/Highlight/stratosphere.shtml
http://www1.ncdc.noaa.gov/pub/data/cmb/temp-and-precip/upper-air/uahncdc.ls
http://www.arl.noaa.gov/documents/JournalPDFs/RandelEtal.JGR2009.pdf
Paywalled:
http://www.nature.com/nature/journal/v491/n7426/full/nature11579.html
Wayne Delbeke says:
August 4, 2014 at 12:04 pm
gregfreemyer says:
Regardless, the likelihood of a collision exciting a GHG molecule in a GHG molecule / random molecule collision has little to do with the presence of water vapor in the neighbourhood.
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It’s a long time since I took Physics but if Water Vapour is the major Green House Gas, why is it excluded as a GHG above? Why wouldn’t a collision between any GHG – CO2 or CH4 or H2O molecule have an effect? I am sure this has been discussed before, but give me an idea of why it has to be some “chosen” gas. Thanks.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Let me rephrase explicitly for CO2.
If one has a volume of air in the stratosphere with 0% humidity, CO2 will act as a cooling agent.
If one has a volume of air in the stratosphere with 100% humidity, CO2 will act as a cooling agent.
The presence of absence of water vapor has no impact on CO2’s interaction with photons and the molecules that compose the stratosphere. Any molecule colliding with CO2 can excite it, but with very low odds. Any molecule colliding with an excited CO2 molecule will with almost 100% certainty de-excite it.
To the best of my knowledge, CO2 has no magical chemical interaction with H2O that affects either the excitation or de-excitation process.
Here is a discussion of the temperature trends at different levels:
http://www.newclimatemodel.com/must-read-co2-or-sun-which-one-really-controls-earths-surface-temperatures/
A scienceofdoom post from 2010 has some good quotes that might expalin it better.
http://scienceofdoom.com/2010/04/18/stratospheric-cooling/
The great Ramanathan in his 1998 review paper Trace-Gas Greenhouse Effect and Global Warming (thanks to Gary Thompson of American Thinker for recommending this paper) says this:
“As we mentioned earlier, in our explanation of the greenhouse effect, OLR reduces (with an increase in CO2) because of the decrease in temperature with altitude.
In the stratosphere, however, temperature increases with altitude and as a result the cooling to space is larger than the absorption from layers below. This is the fundamental reason for the CO2 induced cooling.”
In Ramaswamy (2001):
“For carbon dioxide the main 15-um band is saturated over quite short distances. Hence the upwelling radiation reaching the lower stratosphere originates from the cold upper troposphere. When the CO2 concentration is increased, the increase in absorbed radiation is quite small and the effect of the increased emission dominates, leading to a cooling at all heights in the stratosphere.”
Stephen Wilde says:
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.
===
How do you reconcile that description with the TLS data?
gregfreemyer says:
August 4, 2014 at 11:28 am
Water vapor was offered as just a practical example. As long as the atmosphere holds something other than CO2 there will be something like water vapor that has to be taken into account. Radiation theory, the mathematical equations, applied to an atmosphere of CO2 alone could not yield the result that a higher density of CO2 molecules could result in the cooling of less dense CO2 molecules at a higher level. Therefore, radiation theory alone cannot yield that result for our actual atmosphere. Something else must be added; something like water vapor. For the last time, some natural science that exists apart from radiation theory must be used to get the result that you claim for radiation theory.
Greg Goodman says:
August 4, 2014 at 1:03 pm
So far the quieter sun has only stopped the previous temperature trends as one can clearly see from the TLS data.
One should now watch that data closely to see whether the decline of solar activity from the peak of cycle 24 is accompanied by further changes which fit my hypothesis.
Theo Goodwin said:
“For the last time, some natural science that exists apart from radiation theory must be used to get the result that you claim for radiation theory.”
Correct.
The Gas Laws plus adiabatic warming on convective descent do the job nicely.
The stratosphere (the lower part) is cooling as expected due to a decline in solar activity(less ozone) over the last few decades, in addition it is cooling more in the middle latitudes in contrast to the polar regions also as expected.
I have been saying this for years.
However above 45km ozone amounts and thus the stratosphere temperature run counter to solar activity. This probably due to CME’S and other solar activity which destroy ozone.
Thus less CME’S when sun is inactive more ozone warmer stratosphere above 45 km.
Volcanic activity (lack of it) also playing a role in the stratospheric temp. trend.
Climate weenie:
The TUT Hot Spot is also supposed to appear if the imbalance comes from solar forcing:
Maybe I spoke to soon about the quality of wuwt comments. This is a good point, Climween. The tropospheric hotspot is predicted if there is an inbalance between incoming and outgoing radiation at the top of the atmosphere, regardless of the cause – though you wouldn’t believe it if you restricted your sources of information on climate science to the Noble Viscount or any other of the more strident AGW dismissers. That’s why stratospheric cooling is a far better diagnostic of GHG-induced warming.
Look at the 23-38km band in the 60S-60N graph here:
http://www.acd.ucar.edu/Research/Highlight/stratosphere.shtml
The commentary says:” The time series are punctuated by transient warming events associated with the large volcanic eruptions of El Chichon (1982) and Mt. Pinatubo (1991), which persist for approximately two years.”
Note the fact that after the two volcanoes the temp drops TWICE as much as it rises.
Look at the 37-52km band: all it does is drop !
“The overall cooling ranges from ~-0.5 K/decade in the lower stratosphere (~20 km), to over -1K/decade in the upper stratosphere (40-50 km). These values can be compared with warming in the lower atmosphere (troposphere) over the same period of order 0.1-0.2 K/decade. The time series in Fig. 1 show that the stratospheric changes are not monotonic, but more step-like in nature; note that stratospheric temperatures have been relatively constant over the recent decade 1995-2005. ”
-0.5 K/decade in the lower stratosphere and there were how many eruptions per decade? So another way to express that would be -0.5 K / eruption.
Their equivalence of 0.1-0.2 K/decade ( or per eruption ) is basically what I found here:
http://climategrog.wordpress.com/?attachment_id=988
The reference paper for that page is well worth a look:
http://www.acd.ucar.edu/~randel/2008JD010421.pdf
“… MSU channel 4 data suggest the Antarctic stratosphere has not cooled appreciably since the middle 1990s. Temperature trends in the Arctic stratosphere are not significant during the winter and spring months for two reasons: (1) the Arctic stratosphere is characterized by substantial interannual variability during the cold season (Figure 13), which complicates the detection of trends; and (2) the cooling of the springtime Arctic apparent during the 1990s has not
persisted during the most recent decade. ”
So neither Arctic nor Antarctic has seen any cooling since 2000. Plateaux galore!
Oddly, despite having explicitly noted that the changes are step changes with no trend, they spend most of the paper talking about and evaluating non-existent “trends”.
Though they don’t say it in so many words, it seems that this team has a least recognised what this implies: that there is a rise of 0.1-0.2K in each decade that is directly attributable to volcanic activity. If we are to play straight line games this means 0.1 to 0.2K/decade of warming in the lower climate system as a result of the major eruptions.
Now that is precisely the “unprecedented” warming that got everyone shitting themselves at the end of the last century.
That is precisely the “unprecedented” acceleration in warming that has been basis of exponential extrapolations leading to ridiculous “as much as 6 deg C” claims and broken models.
It is the spurious attribution of these changes to AGW that is the source of the whole problem.
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.
Yeah, but…
even if so, stratospheric cooling does not mean that the troposphere must be warming. That wouldn’t make any (common) sense. It might appear to imply that both couldn’t cool (or warm) at the same time. Further, either way, it does not prove that whichever is happening is being caused by anything we humans are doing.
I suspect some have said similar above.
”
Joseph Bastardi says:
August 4, 2014 at 8:44 am
Now this has my attention! I have always said that the sign of global warming would be a cooling upper stratosphere.. as that would imply expansion below that level and warming! So this is an interesting paper to me and one that I think can gain traction. However it still does not answer the question: is it man made? And we are going to get our answer soon enough given the change in the PDO and AMO would imply tropospheric cooling and warming above again ( reversal of the cooling)
…
”
That stratospheric hotspot BS has always had me perplexed. It probably means that their computer models are just flat out in gross error. What is going on and is going to happen is conservation of energy. When there is increased ghgs in the air at some level – in a shell, there will be x increase in the absorbed energy due to the extra gas absorption. In simple terms of Stefan’s law, there will also be an increase in emissivity (epsilon) causing an increase in radiation from that shell. The increased radiation will be outward and the same amount of increase will be downward, essentially leading to a 2x sized increase in radiation away from that shell unless the T drops and because of conservation of energy – it must drop in T until it reaches a balance in that shell.
It would again seem only logical that the increase in IR radiation in the lower atmosphere will have to result in increased water cycle activity for most of the Earth’s surface as the IR is not going to penetrate into the oceans and a regulating effect from cloud cover is going kick in to trim down the visible light that has some ocean penetration.
Steven Mosher: Stratospheric cooling is the better fingerprint.
Fingerprint of what? If the surface, lower troposphere, and upper ocean do not warm catastrophically, then there will be no catastrophic warming. Stratospheric cooling in the absence of surface warming is the finger print of nothing much to worry about.
Bill H. : That’s why stratospheric cooling is a far better diagnostic of GHG-induced warming.
Stratospheric cooling without surface warming is diagnostic of CO2 increases producing no changes worth expensive public policies with respect to CO2 emissions from fossil fuels: a very slight change in the heat fluxes in the atmosphere, producing no changes with important agricultural or civilizational or biological consequences.
John Who: stratospheric cooling does not mean that the troposphere must be warming. That wouldn’t make any (common) sense. It might appear to imply that both couldn’t cool (or warm) at the same time. Further, either way, it does not prove that whichever is happening is being caused by anything we humans are doing.
I agree, but your first comment was silly.
Salvatore Del Prete says:
The stratosphere (the lower part) is cooling as expected due to a decline in solar activity(less ozone) over the last few decades, in addition it is cooling more in the middle latitudes in contrast to the polar regions also as expected.
Consistent with the observation.
http://www.esrl.noaa.gov/gmd/odgi/odgi_fig3.png
MRM: Stratospheric cooling in the absence of surface warming is the finger print of nothing much to worry about.
There has not been “stratospheric cooling in the absence of surface warming “, there has been both and they were caused by volcanism not AGW..
Randel et al 2009 basically confirms what I have found myself. That paper is 5y old now. Why are we still crapping on about AGW?
I’m reminded of the 2013 NAS study by Santer et al. (http://www.pnas.org/content/early/2013/09/10/1305332110.full.pdf+html). They claimed to find a “discernible human influence” in the thermal structure of the atmosphere — warming in the troposphere (although not as much as forecast, the authors concede) and cooling in the stratosphere. The wording — “discernible human influence — is artful. Echoing the famous conclusion of the IPCC’s Second Assessment Report, Santer et al. insinuate they have found the long-sought greenhouse “fingerprint.”
But although stratospheric cooling could due to greenhouse gas emissions trapping more upwelling heat in the troposphere, it could also be due to ozone depletion (because ozone is itself a heat-trapping, greenhouse gas).
One of Santer et al.’s co-authors is NP Gillett, and the Santer team cites an earlier study led by Gillett (http://www.atmos-chem-phys.net/11/599/2011/acp-11-599-2011.pdf) on the attribution of observed changes in the stratosphere. The bottom line: ” We conclude while the influences of ODSs [ozone depleting substances] and natural forcings are clearly detectable in stratospheric ozone and temperature observations, the influence of greenhouse gas increases is not yet clearly identifiable. A robust separation of the ODS and GHG responses may require a longer period of observations.”
So contrary to what they imply, Santer et al. did not find clear evidence of man-made global warming. Have Zeferos et al. finally succeeded where others failed?
On the face of it, Greg Goodman seems right about the dubious statistical methodology in this paper. There certainly are typical warning signs of problems. But the authors invoke a paper by Reinsel et al(2005) as the basis for their statistical analysis. Reinsel was a very competent statistics professor, apparently a specialist in time series and multivariate regression. In that sense anyway, it’s not from the usual half-baked school of climate statistics.
The lower stratosphere does not exhibit a GHG signal. It shows a volcano/Ozone depletion from volcanic sulphates signal (and I am tired of climate scientists not recognizing this).
http://s11.postimg.org/lxwzon2rn/Volcanoes_and_Lower_Strat_Temps_1978_2014.png