Comments On Tamino’s AMO Post
by Bob Tisdale
Tamino’s AMO post is a response to my post Removing The Effects of Natural Variables – Multiple Linear Regression-Based or “Eyeballed” Scaling Factors (hereinafter referred to as the “Removing” post). Tamino took exception to my inclusion of the AMO as one of the datasets used to explain the rise in GISS Land-Ocean Temperature Index (60S-60N) during the satellite era. Please read Tamino’s AMO post before continuing.
My “Removing” post, as discussed in its opening paragraph, was the second in a series follow-ups to the earlier post Can Most Of The Rise In The Satellite-Era Surface Temperatures Be Explained Without Anthropogenic Greenhouse Gases? (hereinafter referred to as the “Can Most” post). The first follow-up was Notes On Polar Amplification.
And for those new to the Atlantic Multidecadal Oscillation (AMO) please refer to the post An Introduction To ENSO, AMO, and PDO — Part 2.
THE REAL CLIMATE DESCRIPTION OF THE AMO
Tamino wrote in his post,
“Bob Tisdale (and others) simply can’t wrap their brains around the fact that global warming is the cause, not the effect, of much of the changes in N.Atl SST anomaly. Therefore global warming is the cause, not the effect, of much of the variation in the AMO.”
My AMO posts typically include the RealClimate description of the Atlantic Multidecadal Oscillation (“AMO”), but I failed to include it in “Removing” post. RealClimate states, “A multidecadal (50-80 year timescale) pattern of North Atlantic ocean-atmosphere variability whose existence has been argued for based on statistical analyses of observational and proxy climate data, and coupled Atmosphere-Ocean General Circulation Model (“AOGCM”) simulations. This pattern is believed to describe some of the observed early 20th century (1920s-1930s) high-latitude Northern Hemisphere warming and some, but not all, of the high-latitude warming observed in the late 20th century. The term was introduced in a summary by Kerr (2000) of a study by Delworth and Mann (2000).”
Tamino’s opinion contradicts the opinions of his associates at RealClimate, or at least the opinion of the author of the RealClimate AMO webpage. RealClimate describes the AMO as being responsible for some, but not all, of the warming, but Tamino states it’s the other way around, that the global warming signal is the cause of the AMO variability.
Tamino’s RealClimate associates must be among “the others” who “simply can’t wrap their brains around the fact that global warming is the cause, not the effect, of much of the changes in N.Atl SST anomaly.”
A NOTE ABOUT THE SST DATASET USED IN THIS POST
GISS uses two SST anomaly datasets in its Land-Ocean Temperature (LOTI) product: HADISST from January 1880 to November 1981 and Reynolds OI.v2 from December 1981 to present. There is little difference between the HADISST and Reynolds OI.v2 data for the North Atlantic during the satellite era, as shown in Figure 1. So my use of HADISST data in the short-term will not influence the results of this post.
http://i52.tinypic.com/fxyvwp.jpg
Figure 1
However, there is a significant difference between the long-term Kaplan North Atlantic SST data used by the ESRL (and Tamino) and the HADISST data used by GISS. Refer to Figure 2. Keep in mind my use of the ESRL data was only for the AMO index in the short term, not the long-term SST data used by Tamino. (Note: I confirmed via email that the ESRL uses the coordinates of 0-70N and 80W-0 for its AMO data.)
http://i51.tinypic.com/28atkzb.jpg
Figure 2
And the difference does impact Tamino’s post. He uses the wrong North Atlantic SST anomaly dataset when he subtracts global temperatures from it. That is, assuming Tamino did not switch to the HADISST version of the North Atlantic, he biased the results in his last graph by the difference in the trends of the HADISST data (used by GISS) and the Kaplan data (used by ESRL) shown in Figure 2.
ON THE NONLINEARITY OF THE WARMING SIGNAL
The natural multidecadal variability of the North Atlantic SST anomalies is significantly greater than that of the Global (90S-90N) SST anomalies. This is very apparent if we compare detrended North Atlantic SST anomalies (AMO) to detrended Global SST data, Figure 3. The data have been smoothed with a 121-month running-average filter.
http://i54.tinypic.com/xnuvbq.jpg
Figure 3
Tamino opens his post with a discussion of the how the AMO is calculated by detrending North Atlantic SST anomalies, and he notes that the Wikipedia definition warns about the nonlinearity of the actual warming signal. The nonlinearity of the detrended global SST signal is shown clearly in my Figure 5 above. Based on his presentation, Tamino concludes, “Variations in the forced signal do leak into the AMO definition.”
Let’s compare the short-term linear trends of the North Atlantic SST anomalies to the trends of the other ocean basins. This is a general discussion of the AMO, so I’ve left in the Arctic and Southern Ocean data. Keep in mind that my “Removing” and “Can Most” posts only dealt with the period starting in 1982, which is the satellite era for SST data. As shown in the spaghetti graph, Figure 4, the SST anomaly linear trend of the North Atlantic is significantly higher than all other SST basins. The linear trend of the Arctic Ocean SST anomalies comes in second, in part because those two datasets overlap and due to the influence of the North Atlantic on the Arctic Ocean. Regardless, the North Atlantic linear trend is almost twice that of the Arctic Ocean. The North Atlantic trend is more than 3 times higher than the trends of the North Pacific and Indian Oceans and more than 5 times higher than the trends of the South Atlantic and South Pacific. And of course, the Southern Ocean linear trend is negative. (Note: The impact of the Southern Ocean cooling is so substantial that the trend is basically flat for all HADISST anomaly data south of 40S, or about 35% of the global oceans, since 1982.)
http://i56.tinypic.com/vo0ck0.jpg
Figure 4
This difference in linear trends can also be seen in the comparison of North Atlantic SST anomalies and the SST anomalies for the rest of the world. To determine the rest-of-the-world data (identified as “Global Without No Atlantic” in Figure 5), I approximated the North Atlantic surface area as a percentage of the global oceans. The Atlantic represents approximately 30% of the surface area of the global oceans. I assumed the North Atlantic made up half of that, or 15%, before scaling the North Atlantic data and subtracting it from the global data for Figure 5. The linear trend of the North Atlantic SST anomalies is more than 5 times greater than the average of the other ocean basins.
http://i53.tinypic.com/ml1jz9.jpg
Figure 5
In fact, the contribution of the North Atlantic is so great, without it, the global trend drops by 45%, Figure 6.
http://i56.tinypic.com/2zhei46.jpg
Figure 6
Tamino did not suggest how to account for the global warming signal in his AMO post, unless the last graph in which he subtracts global GISS LAND-Ocean Temperature Index data from North Atlantic SEA Surface Temperature data is his recommendation. But he did make a suggestion on his earlier How Fast is Earth Warming? thread. He wrote in response to a January 23, 2011 at 4:42 pm comment, “It might be interesting to correlate AMO to short-term global temperature fluctuations, if AMO is detrended nonlinearly, or if only the modern era (1975 to present) is detrended separately. But then: the denialists’ claim disappears.”
To account for the nonlinear signal, Trenberth and Shea (2006) proposed subtracting the global (60S-60N) SST data from the North Atlantic in “Atlantic hurricanes and natural variability in 2005”. But the North Atlantic represents a major portion (almost 50%) of the recent rise in global SST anomalies (90S-90N) since 1982, Figure 6. Therefore, Trenberth and Shea are suggesting the subtraction of a dataset with a strong North Atlantic signal from the North Atlantic SST data itself. Why not subtract the SST anomalies of the rest of the world from the North Atlantic? It’s the additional variability of the North Atlantic, above and beyond the rest of the world, that’s of interest, not a signal that’s been suppressed by itself.
The reason that method hasn’t been suggested becomes obvious when one compares that dataset to the AMO data based on detrended North Atlantic SST anomalies. Refer to Figure 7. (The “Rest of the World” data is calculated the same as the “Global Without North Atlantic” from Figures 5 & 6.) Note how the curves mimic one another from 1905 to the early 1980s. They diverge from time to time, but the curves are similar. But note how VERY similar the two curves are after 1982. That’s the period of the AMO data used in my “Removing” post.
http://i53.tinypic.com/2v1ukg5.jpg
Figure 7
Let’s look at the satellite-era portion (1982 to present) of those two datasets, Figure 8. The trends are basically the same, and the year-to-year variability of the two signals mimic one another with small divergences and lags. Based on Figure 10, the “Variations in the forced signal do leak into the AMO definition,” as Tamino notes, but they have had little impact on the results of my “Removing” post.
http://i54.tinypic.com/kdpe7c.jpg
Figure 8
THE DIFFERENCE BETWEEN THE KAPLAN AND HADISST NORTH ATLANTIC SST ANOMALIES
The Kaplan and HADISST versions of the North Atlantic SST anomalies were illustrated together in Figure 2. There was a significant difference in their linear trends. For Figure 9, I subtracted the HADISST version of the North Atlantic SST anomalies from the Kaplan SST anomalies used by ESRL (and Tamino for his last graph). Note the similarities between Figure 9 and Tamino’s final graph in his AMO post.
http://i53.tinypic.com/2806uqx.jpg
Figure 9
TAMINO’S FINAL COMPARISONS
Tamino’s post included a comparison graph of Global (90S-90N) GISS LOTI and the North Atlantic SST anomalies he created from the data on the ESRL AMO webpage. The last illustration was a graph of the difference. While I can’t find fault in his not knowing there was a shift in the Kaplan North Atlantic SST data, I can find fault in his using the wrong SST dataset. GISS does not use Kaplan SST.
There is little difference between the HADISST and Reynolds OI.v2 versions of the North Atlantic SST data, as shown in Figure 1. To assure the following comparisons were correct, for the following graphs I spliced those two North Atlantic SST anomaly datasets using the method described by GISS in Step 4 on their current analysis webpage. Had Tamino used the HADISST/Reynolds OI.v2-based GISS SST anomalies for the North Atlantic in his comparison, Figure 10, the difference between it and the Global GISS LOTI data would have maintained the appearance of the AMO.
http://i53.tinypic.com/2hofas0.jpg
Figure 10
And had Tamino detrended both datasets and smoothed them with 121-month filters, Figure 11, he would have noted that the multidecadal variability of the North Atlantic far exceeds that of the Global GISS LOFTI data—even with the additional land surface temperature variability in the LOTI data—even with the exaggeration of polar amplification in the LOTI data—even with the bias caused by GISS’s deletion of polar sea surface temperature data in the LOTI data.
http://i52.tinypic.com/3149sm9.jpg
Figure 11
I’ll respond to his comments about “eyeballing” in another post.
SOURCES
With the exception of the ESRL North Atlantic SST data (linked numerous times in the post), all data are available through the KNMI Climate Explorer:
http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere
I must agree with another poster here, Richard S Courtney, that no one should play along with Tamino. I personally found his behaviour odd to say the least, when I commented one or two times. He pulled a post when I pointed out that he had made a mistake. I REALLY urge people not to post on his website – it’s pointless, really.
Very interesting, that the North Atlantic warms have coincided with the globes warming. I wonder if someone can do a study with the PDO and AMO, since i think the 2 of them together can explain a lot of what has happened in temps since 1900 across the globe.
Great Post, and I agree that Global warming doesn’t cause the AMO to warm, the AMO is seperate of AGW, they just happened to coincide right now
http://climexp.knmi.nl/data/ihadsst2_280-360E_0-70N_n_su_1880:2011a.png
North Atlantic goes up and down, showing no relation with CO2. Unless, you claim the 1975-2005 rise is unprecedented and caused by CO2. The previous part rising and falling, well, the flat line of hockey stick will do.
See how it switched in 2005 back to cooling, despite recent warm peak. Those people are desperate.
“Bob Tisdale (and others) simply can’t wrap their brains around the fact that global warming is the cause, not the effect, of much of the changes in N.Atl SST anomaly. Therefore global warming is the cause, not the effect, of much of the variation in the AMO.”
So… I’m confused… If Global Warming causes the rise in AMO during the late 20th Century, then how could there be an AMO before that? I mean, really, I’m eyeballing the wikigraph, and I clearly see a positive AMO between 1860 and 1900, and another between 1940 and 1960. If global warming provides the heat to “cause” the current one….Where did the heat to fuel the two previous come from?????
He is right though. I can’t wrap my brain around that!
DD More: You asked, “Might this also indicate how GISS has been fudging the temperature data?”
Not really. Land surface temperatures exaggerate ocean variability.
Robert says: “I wonder if someone can do a study with the PDO and AMO…”
The PDO data from JISAO is not sea surface temperature anomaly data. It is a statistical component of it. Refer to:
http://bobtisdale.blogspot.com/2010/09/introduction-to-enso-amo-and-pdo-part-3.html
P. Solar says: “Since you have detailed data to plot for the other oceans why don’t you plot thier sum rather than a crude estimate of how big the Atlantic is and a guess that N.A. is 50%.”
I assume you mean average them. Any method one choses requires weighting and estimates of surface areas.
I don’t see either side of this discussion establishing their position.
It seems odd that N.Atl. is so much more sensitive , but accepting that , I don’t see that that fact argues for or against it being the cause or effect of GW.
However, if it is the cause, where is the heat coming from ? Just observing that there is an oscillation or a trend does not say where the heat comes from that would be the true cause of the warming.
Roy Spencer and R. Lindzen suggest these oscillations are at least partially driven by cloud variation.
I find it funny that Tamino’s blog has been reduced to try to debunk WUWT posts. I posted a similar comment there but for some reason it didn’t pass moderation LOL
I’ve not visited the misnamed “Open Mind” for ages, the condesending tone (At best) of the little bunch of sycophants is just intolerable, let alone the blatant rudeness of Foster himself!
Much the same at (Sur)RealClimate, anything that might deviate them from the path of warming righteousness is dismissed with a wave of the hand.
Wondering Aloud says:
February 3, 2011 at 10:07 am
Tamino just wants us to “wrap their brains around the fact that global warming is the cause, not the effect, of much of the changes in N.Atl SST anomaly.”
In other words we should presuppose without evidence that his hypothesis is true. And we should ignore paleo and other evidence to the contrary because this time is different, for some unexplained reason, from all past time.
Am I the only one who reads his statement that way?
########
The case for Global warming being the cause of changes in a regional index is
simple.
1. The correlation
2. The negative lag.
Since correlation does not prove causation both Bob and Tamino have a problem
Since the lag is negative, that’s a point in Tamino’s favor.
Does not excuse him for being a nasty human. His name is Grant Foster.
I found good correlation between the de-trended Arctic’s temperature and the AMO.
http://www.vukcevic.talktalk.net/NFC1.htm
Odd thing is that some of the monthly CETs (Central England temperature) show also high degree of agreement with the AMO, while others do not.
http://www.vukcevic.talktalk.net/anomalies.htm
“Open Mind”… what an Orwellian name for that site.
Almost as misleading as Cook’s “skepticalscience.” Or “RealClimate.”
Oh well. It all makes sense in this era of warmcold.
steven mosher says: “Since the lag is negative, that’s a point in Tamino’s favor.”
Care to expand on your statement?
Bob Tisdale said
The PDO data from JISAO is not sea surface temperature anomaly data. It is a statistical component of it. Refer to:
http://bobtisdale.blogspot.com/2010/09/introduction-to-enso-amo-and-pdo-part-3.html
in response to my previous post.
So if I read it correctly, the AMO is a measure of actual ocean temperature in the North atlantic, while the PDO is a measure of a certain variability with where the Pacific is warm/cool than, but not the actual temperature of the North Pacific?
If so I wonder what the impact of the PDO in it’s ‘warm phase’ would have on surrounding landmasses and the world, and what impact it has in it’s ‘cold phase’?
“Open Mind”, I’ve always considered it more of a “Vacant Mind”.
I think Bob is correct in replying to Tamino. If he was to stay silent, Tamino and his flock get even more smug with a conceived win under their belt.
Some of Taminos flock will surely read this reply and see that their ‘preacher’ has got it wrong, even if they won’t admit it.
I’d suspect each time one of these posts like Bobs appears at WUWT or CA, Tamino loses some of his followers until only the rusted on gullible ones are left.
I look forward to some of Taminos followers supporting him by posting some comments here showing us why Bob is wrong. C’mon guys, show some guts and courage, post a comment.
If Tamino supporters don’t post a comment, it will say quite a lot not just about Taminos blog, but about Tamino himself and the type of people he has surrounded himself with.
QUESTION: Would you go to war with Tamino denizens at your back?
I thought Grant Foster made glass suns…
Robert asked, “If so I wonder what the impact of the PDO in it’s ‘warm phase’ would have on surrounding landmasses and the world, and what impact it has in it’s ‘cold phase’?”
As the PDO rises, the Eastern North Pacific rises but that is countered by a drop in the the central and western North Pacific. Since the area of the central and western North Pacific is greater than the east, the net is typically a drop in North Pacific SST as the PDO rises.
Land surface temperatures for Northwest North America correlate well with the rise and falls of the eastern North Pacific, and the land surface temperatures of Eastern Asia correlate well with the western North Pacific.
L says:
February 3, 2011 at 3:14 pm
I thought Grant Foster made glass suns…
——-
Also glass eyes… might explain a few things, like the state I was reduced to when I attempted to make sense of his posts several years ago, before giving up on him.
Good Post Bob.
I’m sure Tamino will find many ways to distort what you have presented as he always does.
There are many paper about the North Atlantic and the AMO as a natural climate cycle. These go back a 1000 years in some cases.
The problem is the AMO has a large trend from 1910 to the fall of 2010. It doesn’t from 1760 to today but we are obligated to detrend it so as not to confuse any global warming signal which might be present in it. It still has a 60 year cycle in the recent data but we must remove the upward trend.
I’ve started using the Gulf Stream instead. Almost all of the upward trend in the AMO is from the 0n to 30N component not actually from the North Atlantic.
Here is the Gulf Stream back to 1850 (using ERSSTv3b with HadSST2 appended to it so we can go way back to see if there is a trend. A very small one).
http://img201.imageshack.us/img201/1015/gulfstreamersstv3bhadss.png
The idea from this is that there are 7 or 8 major ocean currents which are the most responsible for moving energy around the planet and exchanging energy with the atmosphere.
These are the Pacific ENSO, the Kuroshio, the Gulf Stream, the Atlantic Equatorial, the Brazil-Malvinas Confluence, the Agulhas and the Antarctic Circumpolar Current.
You can see this in this animation from the US Navy.
http://www7320.nrlssc.navy.mil/global_nlom32/navo/WHOSP1_nlomw12930doper.gif
I’m having a little better luck modeling Hadcrut3 back to 1871 using this method. Still some bugs to work out when I can get the time.
http://img35.imageshack.us/img35/8803/hadcrut3completeoceanmo.png
Bob,
I have a question that may just be a variation of what
P. Solar says:
February 3, 2011 at 1:15 pm
In Fig7&8 you subtract the global minus N. Atlantic from the N. Atlantic. You seem to suggest that in doing this you have removed the AGW trend from this data to reveal the natural variation. It’s strikes me all you have revealed is the difference in the trend between the N. Atlantic and the global, it seems like a leap to try to attribute this to any one cause. There’s no reason to assume that the N. Atlantic region should behave like the the global average to CO2 forcing. Having said that the shape of it is not to conducive to a linear forcing.
I thought Fig3 was interesting. The comparison of detrended global and N. Atlantic looks how arctic polar amplification graphs would look. I did my own graphing using KNMI Climate Explorer trying to avoid an overlap between the Arctic and N.Atlantic data (0N-60N for the atlantic). You get pretty much the same effect as your Fig3. I don’t think it’s just the overlap It would be interesting to know how the amplification effect extends into regions of no ice when sea ice loss is meant to be the driver of this process.
It looks like you’re leading this one on points ATM. I’d still love to see a KO blow.
And if Tamino is reading this. Honestly sneering might get howls from the gallery but it does nothing for those of us who wish to be challenged.
I tried to have a discussion over at Tamino’s “Open Mind” (which turns out to be a very inaccurate description.) Tamino accepted my first post but then deleted others. In support of how all oscillations can cause warming, I replied with the following, but Tamino couldn’t debate it scientifically, so he once again reverted to ad hominems, and deleting post, always a sign that someone is out of real ammunition. Who is Tamino? a real scientist?
So although this is not specifically about the AMO it is applicable
“There are several researchers who show that warming trends can be associated with oscillations. It is more than just sloshing heat around but also the resultant changes in wind patterns and thus heat transport. Asymmetries can create an illusion of average warming. Hurrell has shown that the NAO can explain most of the late 20th century European warming. Rigor and others have shown changing winds associated with the PDO has forced more ice out of the Arctic taking the “ice lid” off of the 2 degree Arctic ocean when air temps are -20 or lower.
Other studies have clearly shown Alaska warmed with the changing winds of the PDO. The changing regime of winds have been associated with increased El Ninos. The 1998 El Nino caused a 0.8 jump in temperatures and then La Nina brought it back down again. That is a temperature change equivalent to the CO2 attribution, without any additional heat but by spreading it around to be measured over a greater spatial scale. So we look at trends but an asymmetry in El Ninos along with the change in winds, and ice and heat transport, can easily cause a warming trend that lasts for the 30-40 year PDO cycle, similar to what Wigley and others have modeled. Most of the fisheries data show global teleconnections with these oscillations with a few years lag times. So in general all these oscillations have been on an upswing.
There is also a solar trend since 1900, and although that may only account for 25 % of the century warming, add that to the PDO oscillation induced increases, the NAO induced oscillations, etc and then there is only a minor amount that I would attribute to CO2.
You stated “Therefore global warming is the cause, not the effect, of much of the variation in the AMO” and that sounds like your attributing the oscillation to AGW, or at least the major amplitude to AGW. If your use of global warming included the solar trend, we can now include that. But what I and and others including Tisdale are arguing is that the oscillations are causing asymmetries in heat distributions that cause warming trends.
Sure the eyeball quote is a good hit point in an adversarial debate, but the focus should be on how oscillations can or can not contribute to trends, which has been the substance of what Tisdale has been arguing. I simply find focusing on the eyeball quote as uninformative and as unprofessional.
Bob Tisdale wrote:
RealClimate states,”….
This pattern is believed to describe some of the observed early 20th century (1920s-1930s) high-latitude Northern Hemisphere warming and some, but not all, of the high-latitude warming observed in the late 20th century. The term was introduced in a summary by Kerr (2000) of a study by Delworth and Mann (2000).”
Tamino’s opinion contradicts the opinions of his associates at RealClimate, or at least the opinion of the author of the RealClimate AMO webpage. RealClimate describes the AMO as being responsible for some, but not all, of the warming, but Tamino states it’s the other way around, that the global warming signal is the cause of the AMO variability.
Tamino’s RealClimate associates must be among “the others” who “simply can’t wrap their brains around the fact that global warming is the cause, not the effect, of much of the changes in N.Atl SST anomaly.”
There is a difference between saying the AMO is responsible for the warming, and saying it is the cause of the warming.
It is clear that the North Atlantic is the portion of the ocean that has seen the most warming over the past 40 years. That is what is meant by the words “is responsible for the warming of the globe. It doesn’t rule out the possibility that some other force is driving the warming of the North Atlantic.
The NAO has not been a strictly periodic or predictable ocean oscillation. It is not that well understood, and was only discovered recently. There is good evidence that the ocean has undergone a warming trend due the GHG induced warming over the past 40 years. If the oceans have been gaining heat, and the surface of the North Atlantic has been getting warmer, it doesn’t make sense to rule out global warming resulting from GHG’s as the ultimate cause.
Even “realclimate” admits Tamino has it backwards, and that it’s ocean temps that drive air temps.
http://www.realclimate.org/index.php/archives/2006/09/why-greenhouse-gases-heat-the-ocean/
According to the September 5, 2006 posting,
“The slope of the relationship is 0.002K (W/m2)-1. Of course the
range of net infrared forcing caused by changing cloud conditions
(~100W/m2) is much greater than that caused by increasing levels of
greenhouse gases (e.g. doubling pre-industrial CO2 levels will
increase the net forcing by ~4W/m2), but the objective of this
exercise was to demonstrate a relationship.”
Note that CO2 hasn’t yet doubled from the 280ppm at the beginning of
the 20th century to now, but when it does, the net effect will be a
warming of the oceans of 4*0.002= a whopping 0.008 C.
Obviously any MEASURABLE changes in ocean warming must be due to
factors other than CO2- most likely cloud cover- A. McIntire