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.
I don’t understand why you just go back only 160 years?
I will say this, we know abrupt climate change has happened many times in the past ,it is the norm not the exception. If anything the last 160 years are the exception, in that the climate has been in more or less one particular regime, with variations in the climate in that particular regime due to the cycles you suggest. They work fine when the climate is more or less in a particular regime, but will not hold up when an abrupt climatic event takes place, which is when, not if.
I think in order to really have a really complete understanding of earth’s climatic system this abrupt climate change issue has to be addressed.
Going back 160 years to 1850 ,I would say ther were zero events or sequences of events were present during that time period ,which would promote an abrupt climate change, hence we had no abrupt climate changes post 1850.
We had a steady active sun, with a more or less rhythmic 11 year sunspot cycle in place, we had no exceptional geological activity, earth’s magnetic field showing no unusal weakness(although it is weakening),we had an average more or less atmospheric circulation, which more or less resulted in cloud cover,snow cover and precipitation to be ranged bound. Variations yes but within a range, which were governed by the cycles you suggest which were also range bound during this time period.
Then when the beginning state of the climate is applied to the solar ,geological ,atmospheric circulatioin, ocean cycle variation, parameters, we had at that time up to year 2005, one can see why the climate was so steady ,or I should say within a particular regime.
However post 2005, this in my opinion is no longer the situation. The potential now for the first time since 1850 exist for a more rapid climate shift or change, due to this prolong solar minimum ,that commenced in year 2005.
We have had so far 7 years of sub -solar activity ,and prior to that we had 150 years of more or less very very active solar activity. Just look at the aa index, how it increased during the last century, which can be correlated to the the temperature rise.
Now we have a prolong solar minimum which is going to cause sigificant changes in solar wind speeds, uv light emissions, and geomagnetic activity on earth. These solar changes if strong enough in degree of magnitude and duration of time ,and if following enough years of prior sub-solar activity, could cause the climate system of earth to reach critical threshold values which could for lack of a better word flip it into another climate regime, or at the very least bring a significant change to the current state, the climate has been in for the past 150 years.
One must appreciate all the secondary effects that come from changes in solar parameters,(solar wind,uv emissions,solar irradiance) ranging from changes in ozone, cosmic rays, geological activity, ocean circulation patterns,ocean heat content, etc etc, which in turn have effects on the atmospheric circulation,so2 concentrations, clouds, precipitation,snow cover etc. etc,, which in turn will effect the albedo of the earth,(especially the n.h) and if not the temperature dropping per say, at least a different distribution of temp. in the N.H.,due to an atmospheric circulation which is set up to be more meridional then it has ever been ,probably since the Dalton Minimum. The set-up is in due to the abrupt change from a very active sun to what we have now, and the low amounts of Arctic Ice, the warmish Arctic in general ,the warm AMO, which are a compliment to the the sun’s role in promoting a more meridioanl atmospheric circulation due to changes in ozone distributions.Not to forget a substancial increase in high latitude geological activity (volcanic activity)which will further promote a more meridional atm. circualtion ,while increasing (causing cooling)so2 concentrations. Increase geological activity beng correalted to weak solar and weak earth magnetic fields.
I maintain a meridional atmospheric cirulation if maintained long eough, and to a degree strong enough wil have profound climatic impacts,especially for the N.H.
That is all I want to say,I could go on much longer but don”t have the time, but I think you can get the jest of where I am coming from,from what I did say.
Your work is good, but it upsets me to no end when you think the AGW cause ,is going to almost balance out the natural causes that will be impacting the climate going forward. It almost cancells out all your great work. Co2 has zero effect on the climate at these levels.
Also you yourself said an albedo change of 1 to 3% could occur, if that is the case, you would be suggesting a much greater fall in the overal temp. of the earth then what you actually forecast,never mind distribution changes in the temperature of the earth, especially in the N.H.
Your work in the solar areas is sensational, I have to say among the best I have ever seen, you know way more then I could ever hope to know in that paricular area. The best.
BPL 10/18 12:07pm: “Then why is Mercury, which is much closer to the Sun, cooler than Venus by almost 300 degrees?”
Because Mercury has only a trace GHE. Venus GHE acts on heat flow due to its huge atm. emissivity. Absent GHEs effect on heat flow, find Mercury surface hotter than Venus surface.
No GHE, 0 emissivity: Venus surface Teq. = 232K
No GHE, 0 emissivity: Mercury surface Teq. = 456K
———————————————
The math: w/basic, idealized radiation 1st principles where e=emissivity of atm.
Compute planet net solar irradiance S from total solar radiant energy So: S = So*(1-albedo)/4
Find Teq at surface spread over entire planet from: Teq ^4 = S/(c*(1-e/2))
Mercury avg. So ~10,404 W/m^2, albedo = 0.068, find S = 2,424 W/m^2
Mercury avg. Teq. = 456K for 0 emissivity of trace atm. (actual Tmin. ~100K, Tmax. ~700K)
Use same eqn.s w/Venus data find Teq. = 232K for 0 emissivity (non-GHE) theoretical atm.
QED: Mercury Teq. hotter than Venus Teq. w/no GHE.
Add in Venus actual atm. emissivity GHE +500K find Venus hotter mean Tavg. = 732K.
—————————————–
Compare Earth avg. orbit radius So ~ 1369 W per m^2, albedo ~ 0.30, find S ~ 240 W per m^2.
Using eqn.s in paragraph above & no warranty for typo.s:
c = Stefan-Boltzmann constant
e = radiative emissivity of planetary atmosphere averaged over emission spectrum;
set e = 0 for no infrared-active gases (commonly non-GHG), compute Teq for Earth = 255K,
reset e = 0.8 for actual infrared-active gases ppm in Earth atm. to get Teq = 288K
So BPL can see math for where the Earth GHE comes from (288K – 255K = 33K GHE)
Venus closer sun orbit, albedo ~0.75, e=0 non-GHG shows 232K (~732K – 232K = 500K GHE).
Mars further from sun orbit, albedo 0.25, e=0 non- GHG shows 210K (~215 – 210 = 5K GHE).
I believe Salvatore may well be right in suggesting the sharp drop in solar magnetic field strength in 2005 as a possible sign of coming abrupt climatic change. The resulting secular increase in incoming cosmic rays is well illustrated in the Oulu neutron data. Go to http://cosmicrays.oulu.fi/#database and generate a plot beginning Feb 15th 1998 – present.
It starts at the 22/23 minimum which is the maximum for incoming GCRs. Compare this with the 23/24 minimum (GCR maximum) in Dec 2009. Also look at the levels of GCR near the 23 solar cycle peak (GCR minimum) cf the curent levels which are close to or at least about 1 year short of the 24 maximum (GCR minimum). The 23/24 Dec 2009 GCR max is beyond anything seen in the modern era and in line with the Livingston and Penn data suggests a possible sudden plunge into a Maunder type minimum possibly via an increase in cloud cover and increased albedo.
richardscourtney says:
October 17, 2012 at 3:33 pm
And the CO2 in the atmosphere of Venus is not relevant to the climate of Venus which is a net emitter of radiation.
I’m afraid you’ve been misinformed Richard, for reference the cloud tops on Venus have an IR brightness temperature of ~237K.
GCR, just beng one of the many impacts to the climate system from a prolong solar minimum condition. There are many .
It is a new ball game post 2005. Why someone like Nicholas Scafetta, who knows his solar so well,reaches the temperature forecast he does, does not add up given what he knows.
Here is something that might help. Go to this web-site ICECAP.COM, then click, about climate change, then look under topic historical perspective. You will see something titled the Greenhouse Score Card. This essentially takes a look at over 30 predictions the models made on the climate in regards to co2 and the resulting effect expected, and scores each of the predictions based on the data since the model prediction was made.
Almost (98%) all the model predictions have been proven to be wrong.
His temperature projection (nicholas) does not make sense, especially given the fact he admits albedo changes of up to 3% could result from solar changes. A 3% increase in albedo equals about a 1.3 drop in temperature. It does not add up.
1.3 centigrade drop in temp
One last item, is one has to appreciate the rise ocean heat content underwent from around 1960-2005, due to the strong solar activity ,again look at the aa index. Ocean Heat Content takes a long time to wind down, and this is what is currently keeping the temperatures higher then they would be otherwise,( along to solar cycle 24 max. to a lesser degree) both ocean heat content and solar 24 max .wil become less and less factors as this decade proceeds.
If this prolong solar minimum condition as Nicholas Scafetta says is going to go on to the 2030’s , I just don’t see how the temperature will hold up to his projected levesl which in my opinion are much to high. I think the average temp. drop for the N.H. by decade end will be around -1.2 C, with the biggest drops over land areas between 30n -65 n., and drops less then -1.2 c elsewhere. Polar areas may for example remain unchanged.
salvatore del prete says:
However post 2005, this in my opinion is no longer the situation. etc….
****************************
Ok, we will see what will happen. However, from 2005 to now my prediction is holding well.
See my figure here:
http://www.duke.edu/~ns2002/#astronomical_model_1
http://www.duke.edu/~ns2002/scafetta-forecast.png
I agree with your prediction up to 2005. I don’t expect much of a temp. decline until the maximum of solar cycle 24 passes on by. As weak as it is, it is still generating moderate solar activity, way to high for the low solar values I am looking for to have a climate impact. That should pass however once this maximum is over and done with. I say post 2014 or 2015.
Surprisingly some of “the team” have made some quasi empirical calculations of the Maunder effect on climate
“Shindell et al. 2001
Shindell, D.T., G.A. Schmidt, M.E. Mann, D. Rind, and A. Waple, 2001: Solar forcing of regional climate change during the Maunder Minimum. Science, 294, 2149-2152, doi:10.1126/science.1064363.
We examine the climate response to solar irradiance changes between the late 17th century Maunder Minimum and the late 18th century. Global average temperature changes are small (about 0.3° to 0.4°C) in both a climate model and empirical reconstructions. However, regional temperature changes are quite large. In the model, these occur primarily through a forced shift towards the low index state of the Arctic Oscillation/North Atlantic Oscillation as solar irradiation decreases. This leads to colder temperatures over the Northern Hemisphere continents, especially in winter (1-2°C), in agreement with historical records and proxy data for surface temperatures.”
These numbers would fit quite well with the paper recently discussed on WUWT
http://www.academia.edu/1515229/The_extra-tropical_Northern_Hemisphere_temperature_in_the_last_two_millennia_reconstructions_of_low-frequency_variability
Salvatore — looks like you and I are on the same page – I agree completely with your 12.26 post.
No doubt – great minds think alike.
Phil:
re your post addressed to me at October 19, 2012 at 10:56 am, I refer you to the body of my much earlier post at October 18, 2012 at 12:38 pm.
Richard
R: “The math” must be wrong because the ‘Hot Spot’ is missing.
BPL: I think you’ve conflated two different issues here. The question is whether a warmer upper layer of atmosphere would in turn warm a lower layer. It would. Again–want the math?
Trick, what’s “GHE?”
S de Prete,
My information is that the models have made seventeen correct predictions. I have a list of them, with references for each prediction and each later confirmation:
http://bartonpaullevenson.com/ModelsReliable.html
richardscourtney says:
October 19, 2012 at 2:12 pm
Phil:
re your post addressed to me at October 19, 2012 at 10:56 am, I refer you to the body of my much earlier post at October 18, 2012 at 12:38 pm.
Fine, at least you know that you were misinformed and won’t repeat the same error again.
BPL 2:57pm => GHE = commonally the so called green house effect. Really is the atm. emissivity effect. Composition of an atmosphere does matter to determine the emissivity e.
Phil.:
Thanks for your post at October 19, 2012 at 4:41 pm.
I love the sight of a troll desperately floundering in the morning. 😉
Richard
I suggest one should look at the greenhouse scorecard to see how the models are doing. I have yet to see one model prediction turn out correct, which is not surprising since they have incomplete data, data that is not accurate ,or comprehensive enough to begin with. Plus the beginning state of the climate can’t be put into the models properly.
The FACT that the hot spot is missing, the stratosphere has not cooled ,along with no decrease in olr , puts the nail in the coffin, for the AGW theory. I say it has been proven wrong.
An upper warmer level of air , will not warm a lower level. Unless you want to change the second law of thermodynamics, which won’t surprise me since the AGW side will do anything to prove there obsolete points.
All those 17 predictions are wrong, look at the data. Again look at the greenhouse scorecard it gives the data versus the model predictions. All of them are flat out wrong.
Example: the stratosphere has NOT cooled,as you claim that is one of the 17 model predictions that is correct.
The atmospheric circulation is becoming more MERIDIONAL with an equatorward shift in the jet stream, not toward the poles. Just look at the ao/nao index since 2008 or so.
There is no sign of any positive feeback between co2 and water vapor (the missing hot spot, it is NOT there,look at rhe data),enso is tending toward more La Ninas, which COOL the tropics. We can go on and on.
The models are completly wrong, and the data confirms this on every single level without exception.
I made a copy of those 17 predictions. Also if you would plot the aa index versus the temperatures you will(over the last 120 years or so) see a much stronger correlation between that index and temp. versus co2 changes and temp. That is a fact. That is what the data shows, I am going by the data.
A Tale of Two Altitudes: how stratospheric temperature is de …
wattsupwiththat.com/…/a-tale-of-two-altitudes-how-stratospheric-tem…
Apr 30, 2012 – The stratosphere has been warming since at least 1995 or so, exactly …. sou
I can back up everything here.
On another note,The outgoing long wave radiation failing to decrease as a result of an increase in co2 is very damming to the AGW argument.
You can’t argue with the data.
Dr. Norman Page, good paper. It shows the temp. has been variable long before the co2 issue came into play. More variable infact then as oppossed to now.
As I had said it is as much about the distribution of temp. changes as it is about the actual decline in temperature, because I think the globe as a whole may cool by.8c by the end of the decade,and latitudes 65n-90n may be the same, while n.h. latitudes 30n-65 n may show a -1.2 c decline in temp., and this is where it matters the most.
The thing is there are thresholds out there , and I don’t know exactly what they are but if solar reaches xxx values for xxx years they will come about.
On the other side this ocean heat content build up late last century is gong to have a lag effect on the temperature decline, but I think as I have said this will become less of a factor as sub-solar activity years accumulate, and if we go into deep solar minimum values once this weak max. of solar cycle 24 passes by.
One thing I am 100% sure of is the temperature rise is over.It is just a matter of how low we go from there and where the effects are felt the most, and how fast or slow it occurs..
Thank You Dr. Page.