Tamino (aka Grant Foster) will have his knickers in a twist over this one.
Guest post by Marcel Crok (from his blog De staat van het klimaat)
An interesting new paper (behind paywall) has been accepted for publication in the Journal of the Atmospheric Sciences. The paper by Jiansong Zhou and Ka-Kit Tung of the University of Washington, Seattle is titled “Deducing Multi-decadal Anthropogenic Global Warming Trends Using Multiple Regression Analysis”.
This paper will add fuel to the recent discussions about the nature of the global warming trend and whether it recently has stabilized or not. The authors by the way conclude it has not. Their main conclusions however is:
When the AMO is included, in addition to the other explanatory variables such as ENSO, volcano and solar influences commonly included in the multiple linear regression analysis, the recent 50-year and 32-year anthropogenic warming trends are reduced by a factor of at least two. There is no statistical evidence of a recent slow-down of global warming, nor is there evidence of accelerated warming since the mid-20th century.
This study is following the same approach as Foster/Rahmstorf 2011 and Lean/Rind 2008 (trying to correct the global temperature for ENSO, solar and volcanoes) but adds the Atlantic Multidecadal Oscillation to their multiple linear regression analysis. This leads to their figure 1b above. What we see is a longterm trend that has hardly changed during the past century.
Now as always this result can be interpreted in many different ways. The century scale trend is still 0.68 degrees Celsius suggesting little of the total trend of 0.8 degrees C can be attributed to solar, volcanic, ENSO and AMO. That’s what the authors seem to suggest as well when they write (bold mine):
The conclusion that we can draw is that for the past 100 years, the net anthropogenic trend has been steady at approximately 0.08 °C/decade.
So for them anything that’s left after filtering out the natural forcings and natural variability is just ‘anthropogenic’. For me this conclusion is rather premature. But before I explain why let’s focus on the other trend lines that the authors show. Just like Foster/Rahmstorf they conclude that there is no slowdown recently:
There is no statistical evidence of a recent slow-down of global warming
However the trend they find for the recent 32 years (0.07ºC/decade) is far lower than that of Foster/Rahmstorf (0.17ºC/decade). If the approach has any validity at all this would suggest that the AMO alone explains the difference between the Zhou/Tung and Foster/Rahmstorf trend.
The paper by Zhou claims that in the last 32 years, the period in which greenhouse gases are supposed to be the dominant forcings, in fact some 60% (0.1ºC of the total 0.17ºC/decade) of the trend can be ‘explained’ by a combination of ENSO, AMO, solar and volcanic forcing). Ergo, only 40% of the trend could be attributed to other factors among which greenhouse gases are of course a logical candidate.
However there are other candidates as well of course. There is ongoing debate about the influence of siting issues on the temperature measurements on land as well as the Urban Heat Island effect and other socio-economic influences. In a controversial and well known paper Michaels/McKitrick estimated that “Using the regression model to filter the extraneous, nonclimatic effects reduces the estimated 1980–2002 global average temperature trend over land by about half.” If true even less of the remaining trend can be attributed to greenhouse gases.
The Zhou study could therefore have serious implications for our estimates of climate sensitivity. The paper though is completely silent about these potential implications, something that reviewers could have raised.
As said above Zhou and Tung call the remaining century long ‘underlying’ trend ‘anthropogenic’. Whether this is ‘right’ could be questioned with their figure 2 (see below). Here one sees that the anthropogenic forcing (green line) seems to underestimate the adjusted trend in the period (1889-1970) while it seems to overestimate the trend thereafter. This suggests that still not all the relevant factors (either natural or anthropogenic forcings or natural variability) are included in the regression analysis. The residuals in figure 2b still show trends which would not be the case, Zhou and Tung write, if the regression analysis would be perfect.
This leaves enough room for all to bend the paper in one’s preferred direction.
======================================================
Deducing Multi-decadal Anthropogenic Global Warming Trends Using Multiple Regression Analysis
| Abstract |
|---|
In order to unmask the anthropogenic global warming trend imbedded in the climate data, multiple linear regression analysis is often employed to filter out short-term fluctuations caused by El Nino-Southern Oscillation (ENSO), volcano aerosols and solar forcing. These fluctuations are unimportant as far as their impact on the deduced multidecadal anthropogenic trends is concerned: ENSO and volcano aerosols have very little multi-decadal trend. Solar variations do have a secular trend, but it is very small and uncertain. What is important, but is left out of all multiple regression analysis of global warming so far, is a long-perioded oscillation called the Atlantic Multi-decadal Oscillation (AMO). When the AMO Index is included as a regressor (i.e. explanatory variable), the deduced multi-decadal anthropogenic global warming trend is so impacted that previously deduced anthropogenic warming rates need to be substantially revised. The deduced net anthropogenic global warming trend has been remarkably steady and statistically significant for the past 100 years.
Wrong approach, the correct approach is looking at the correaltion between the aa geomagnetic index and the temperature response on earth. Let’s base it on a 1910 value.
time period avg aa index temp value
1900-1920 14 1910 value
1980-1996 27 +.6c
Maunder Minimum 0 to 12 -.6c
That is the correct approach, all this other talk is garbage.
time period – 1900-1920 ap average index 14 temp 1910 value
time period – 1980-1996 ap average index 27 temp. value +.6c
maunder minimum ap average value 0-12 temp. value -.6c
Barton Paul Levenson:
I am ignoring the invitation to debate the climate of Venus although that would be interesting. WUWT has a severe troll infestation today and discussion of Venus would be a disruption to this thread which is about the Earth’s climate.
I am replying to the statement in your post at October 18, 2012 at 7:15 am which says
It seems you are unaware that the IR absorbtion of CO2 in the atmosphere is constrained to only two narrow bands with almost all being in the 15 micron band. These bands are so near to saturation that they only increase their absorbtion by band broadening.
Think of light (i.e. visible radiation) entering a room through a window. If you put a layer of dark paint over the window then much light is absorbed by the paint and, therefore, does not enter the room. Add another layer of paint and more light is absorbed by that layer, but not as much as by the first layer. Similarly for each additional layer of paint.
The IR emitted from the Earth’s surface is trying to pass the ‘window’ of the atmosphere to enter space. Adding more CO2 to the air is like adding more paint on the window that has seven layers of the paint. Each unit addition of CO2 has less absorbtion than the previous unit addition: this reducing effect is logarithmic.
Empirical – n.b. not model-derived – determinations indicate climate sensitivity is less than 1.0deg.C for a doubling of atmospheric CO2 equivalent. This is indicated by the studies of Idso from surface measurements
http://www.warwickhughes.com/papers/Idso_CR_1998.pdf
and Lindzen & Choi from ERBE satelite data
http://www.drroyspencer.com/Lindzen-and-Choi-GRL-2009.pdf
and Gregory from balloon radiosonde data
http://www.friendsofscience.org/assets/documents/OLR&NGF_June2011.pdf
If climate sensitivity is less than 1 deg.C for a doubling of CO2 equivalent, then it is physically impossible for the man-made global warming to be large enough to be detected because natural variability is much, much larger. If something exists but is too small to be detected then it only has an abstract existence; it does not have a discernible existence that has effects (observation of the effects would be its detection).
As you say, the concentration of CO2 in the air has increased by ~40% since the industrial revolution (i.e. from ~280 ppmv to ~390 ppmv). This takes the degree of absorbtion of CO2 to ~80% of a doubling of CO2 in the atmosphere because of the logarithmic effect. And the globe has only warmed about 0.8deg.C since the industrial revolution. Most – if not all – of this rise is certainly recovery from the Little Ice Age (LIA), but if it is assumed the entire temperature rise is from the CO2 increase then a further increase to reach double pre-industrial concentration (i.e. to ~560 ppmv) would only provide a further increase to global temperature of about 0.2 deg.C. And a further doubling of atmospheric CO2 (to 1,120 ppmv) would only raise global temperature by an additional 1.0 deg,C.
In summation, as I said, at present levels of atmospheric CO2 concentration additional CO2 in the atmosphere has no discernible effect on the Earth’s climate.
Richard
One can see the strong correlation, and once the aa index falls below sub 5 ,which it will, once this maximum of solar cycle 24 passes by, because we are in a prolong solar minimum period, the temp. will show a more definitve down trend.
Ocean Heat Content lag holding back things ,but the accumulation of sub-solar years is increasing up to 7 ,and the ohc should become less of a factor going forward, since it is visible light which contributes to the ocean heat content ,not infra-red light. Co2 absorbs infra-red light(15 microns) it does NOT absorb visible light.(.5 microns). Infra-red light having ZERO effects on OHC.
Co2 is a non player. We have the perfect set-up for global cooling. We want a warm amo, we want less arctic sea ice, because these two factors will aid in driving the atmospheric circulation toward a more meridional circulation(-ao/-nao),with the main factor being prolong minimum solar activity(due to ozone distribution changes between high latitudes versus lower lat. in the uppe rtrop/lower stratosphere) but those two factors will aid in accomplishing this.
A meridional atmospheric circualtion is going to drive down the N.H. temp. or at least distribute the temp. profile in such a way that the latitudes 30n-65n are going to be colder, and probably the whole hemisphere colder as a whole, although latitudes above 65n could be more or less the same.
This is the correct path, all this other talk about amo temp correlation,co2 ,volcanic activity ,enso,pdo, apart from eveything else as if THEY are the ONLY factors is a waste of time.
All those except for co2 do play a part, an important part, but it has to be evaluated in the contex of the overall picutre. You can’t isolate them,everyting is interconnected and it starts and is driven by the sun.
Again the sun is to the climate, like what gasoline is to a car, it drives the climate, and influences all the parts that make up the climate, to give an end result.
This paper is just ridiculous, written by these two, and the IPCC is a joke.
should be aa average, although ap and aa are almost the same. I meant to use aa
nah?, what did I tell you. It is just going to get colder and colder.
It will take another 4 years before we have “bottomed out”.
http://blogs.24.com/henryp/2012/10/02/best-sine-wave-fit-for-the-drop-in-global-maximum-temperatures/
stop worrying about the carbon. Start getting worried about the cold.
Can you remove ENSO and AMO by linear regression? Is this a valid approach?
S del Prete: I meant from this level, where all of the effects of co2 as far as absorbing long wave radiation are at or very close to the saturation point, therefore adding additional co2 (from this level)will have very little further effects, on the temperature.
BPL: It’s not saturated at the upper levels, and warming anywhere there will propagate down to the surface. It’s easy to demonstrate if you want the math.
RH: Yes, the “amount”: because the amount makes the Venusian air so dense you could swim in it (if the heat would wait a bit before burning you up). It is definitely the adiabatic lapse rate due to the “amount” – air pressure, not some property of CO2 specifically.
BPL: No. You would have the same lapse rate whatever the surface temperature, because the adiabatic (“dry”) lapse rate is solely a function of the local gravity and the specific heat of the air (cp rather than cv). With less CO2 in the air, Venus would be cooler, its atmosphere would not reach as high for the same pressures, but the lapse rate would stay the same.
By using the AMO index, this paper essentially adds the 60-year oscillation observed in the climate system to previous regression models that did not contained it.
Too bad that the authors did not references any of the previous works that essentialy did the same and arrived to a similar conclusion that recent anthropogenic warming trend (since 1970) needs to be cut about by half.
Just my works are here:
Scafetta N., 2010. Empirical evidence for a celestial origin of the climate oscillations and its implications. Journal of Atmospheric and Solar-Terrestrial Physics 72, 951-970.
Loehle C. and N. Scafetta, 2011. Climate Change Attribution Using Empirical Decomposition of Climatic Data. The Open Atmospheric Science Journal 5, 74-86.
Mazzarella A. and N. Scafetta, 2012. Evidences for a quasi 60-year North Atlantic Oscillation since 1700 and its meaning for global climate change. Theoretical Applied Climatology 107, 599-609.
Scafetta N., 2012. A shared frequency set between the historical mid-latitude aurora records and the global surface temperature. Journal of Atmospheric and Solar-Terrestrial Physics 74, 145-163.
Scafetta N., 2012. Testing an astronomically based decadal-scale empirical harmonic climate model versus the IPCC (2007) general circulation climate models. Journal of Atmospheric and Solar-Terrestrial Physics 80, 124-137.
Scafetta N., 2012. Multi-scale harmonic model for solar and climate cyclical variation throughout the Holocene based on Jupiter-Saturn tidal frequencies plus the 11-year solar dynamo cycle. Journal of Atmospheric and Solar-Terrestrial Physics 80, 296-311.
Scafetta N., 2012. Does the Sun work as a nuclear fusion amplifier of planetary tidal forcing? A proposal for a physical mechanism based on the mass-luminosity relation. Journal of Atmospheric and Solar-Terrestrial Physics 81-82, 27-40.
Look at my web-site or details.
http://www.duke.edu/~ns2002/#astronomical_model
Of couse the present paper does not explain what it the physical cause of the 60-year AMO oscillation. This issue is also addressed in my papers by finding it among the natural oscillations of the solar system.
Will: It is fairly easy to demonstrate that the temperature difference between Earth and Venus at the same pressure density is solely accounted for by distance from the Sun, not the composition of the atmospheres.
BPL: Then why is Mercury, which is much closer to the Sun, cooler than Venus by almost 300 degrees?
Nicholas Scafetta, is on the basic correct path. I agree with his basic assumpitons.
The problem with Nicholas Scafetta, is he is under estimating the natural forces that will be at work on the climate system, and falling for the AGW hoax to a degree. So his temperature projections wiLl be way to high going forward.
Another problem with Mr. Scafetta, although I agree with his basic assumptions ,is he does not seem to have a grasp on all the secondary effects which will come into play if solar conditions should meet certain critical threshold values, for a long enough sustained period of time, following years of sub-solar activity prior to these values being attained, and years of prior very active solar actiivty (1850-2005) before the sub-solar activity which started in year 2005. This all comes into play. It is all part of the puzzle.
Also the earth’s magnetic field strength will have a role in this.
Barton Paul Levenson:
I began my post addressed to you at October 18, 2012 at 8:04 am by saying
Reviewing your subsequent posts in the thread I can only conclude that sometimes it is hard to put a good troll down.
Richard
PS It does not matter what your “calculations” say because empiricism trumps theory: read my post which I cite in this post.
Barton,it is not happening as evidence by the amount of outgoing long wave radiation being emitted from the earth out to space. It is NOT decreasing.
Also if this was happening we would have seen evidence of stratospheric cooling,again this is NOT happening.
Warming will propogate to the surface, I don’t think so. Don’t work that way.
From Scafetta, to these two that wrote this paper, just about everyone does not approach the climate situation in a comprehensive enough manner. I have 17 categories for the climate and I keep them all updated with data, and how it applies or does not apply to a possible change.
The only persons I have come across that really has this situation down our Joe D’Aleo ,and Joe Bastardi both of weatherbell..
SdP: Warming will propogate to the surface, I don’t think so. Don’t work that way.
BPL: Sure it does. Warm objects radiate. A warmer high level of air radiates in all directions, including down to lower levels. Why wouldn’t it?
R: It does not matter what your “calculations” say because empiricism trumps theory
BPL: Which physical law, based on empirical observation, do you disagree with? Stefan-Boltzmann? Wien? Kirchhoff? The ERT? What empiricism, in particular, trumps calculations of mine you haven’t even seen yet?
Second Law of Thermodynamics: It is not possible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow. Energy will not flow spontaneously from a low temperature object to a higher temperature object. This precludes a perfect refrigerator. The statements about refrigerators apply to air conditioners and heat pumps, which embody the same principles.
This is the “second form” or Clausius statement of the second law.
Alternative statements: Second Law of Thermodynamics
Index
Second law concepts
Heat engine concepts
HyperPhysics***** Thermodynamics R Nave
Go Back
Second Law of Thermodynamics: It is not possible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow. Energy will not flow spontaneously from a low temperature object to a higher temperature object. This precludes a perfect refrigerator. The statements about refrigerators apply to air conditioners and heat pumps, which embody the same principles.
This is the “second form” or Clausius statement of the second law.
Alternative statements: Second Law of Thermodynamics
Index
Second law concepts
Heat engine concepts
HyperPhysics***** Thermodynamics R Nave
Go Back
My point ,co2 does not create energy or better is not a source of energy, so how could heat flow down from a colder body the atmosphere to a warmer body the earth’s surface???.
Barton , I bet you could kill me in math any day of the week, but I hope you will look over what I had to say today in my many post about the climate and why so many of the articles don’t do it any justice.
I hate to keep picking on Nicolas Scafetta, but he ignores abrupt climate change completly, because that does not fit into his cycles. I can’t take anyone to seriously that does not address abrupt climate change. Abrupt climate change being ever present (many many times in the past) and happening as quickly as a decade,or less sometimes.
I address this issue in detail. Infact absolutely none of the papers visit this vital topic, especially the one done by these two so called experts.
Barton Paul Levenson:
At October 18, 2012 at 3:23 pmyou say to me
The “calculations” are those which you mentioned at October 18, 2012 at 10:42 am where you wrote
“The math” must be wrong because the ‘Hot Spot’ is missing.
I agree with all the physical laws. But I am not an idiot so I know that attempting to apply physical laws to a complex and partially understood system usually provides wrong answers. And the empirical evidence clearly shows your assertion is wrong. Simply you have done some sums to assess what you think is how the climate system works but reality demonstrates the system is nothing like you think it is.
Try applying physical laws to calculate the behaviour of the human brain and see what you get: the climate system is more complex than the human brain. (And don’t try to use that illustration as an excuse to troll the thread about brain structure).
Richard
The hotspot in the lower trop. near the equator no where to be found another big blunder. I am glad you mentioned that. Where is the so called positive feedback between co2 and water vapor. Answer missing in action.
Here is another big blunder. They, the models said the atmospheric circulation index would become more positive with time, guess what it is becoming more negative with time.
I have over 30 blunders they ,the models have made. They are in a word ,useless.
Salvatore del prete says:
October 18, 2012 at 4:01 pm
I hate to keep picking on Nicolas Scafetta, but he ignores abrupt climate change completly, because that does not fit into his cycles.
*************
See dear Salvatore, for taking into account “abrupt climate change” dynamics one needs first to find an event that can be interpreted as such. Excactly, in the last 160 year since 1850 where and when do you see “abrupt climate change” dynamics that needs to be taken into account with appropriate non linear models?