Warming in Last 50 Years Predicted by Natural Climate Cycles
by Roy W. Spencer, Ph. D.
One of the main conclusions of the 2007 IPCC report was that the warming over the last 50 years was most likely due to anthropogenic pollution, especially increasing atmospheric CO2 from fossil fuel burning.
But a minority of climate researchers have maintained that some — or even most — of that warming could have been due to natural causes. For instance, the Pacific Decadal Oscillation (PDO) and Atlantic Multi-decadal Oscillation (AMO) are natural modes of climate variability which have similar time scales to warming and cooling periods during the 20th Century. Also, El Nino — which is known to cause global-average warmth — has been more frequent in the last 30 years or so; the Southern Oscillation Index (SOI) is a measure of El Nino and La Nina activity.
A simple way to examine the possibility that these climate cycles might be involved in the warming over the last 50 years in to do a statistical comparison of the yearly temperature variations versus the PDO, AMO, and SOI yearly values. But of course, correlation does not prove causation.
So, what if we use the statistics BEFORE the last 50 years to come up with a model of temperature variability, and then see if that statistical model can “predict” the strong warming over the most recent 50 year period? That would be much more convincing because, if the relationship between temperature and these 3 climate indicies for the first half of the 20th Century just happened to be accidental, we sure wouldn’t expect it to accidentally predict the strong warming which has occurred in the second half of the 20th Century, would we?
Temperature, or Temperature Change Rate?
This kind of statistical comparison is usually performed with temperature. But there is greater physical justification for using the temperature change rate, instead of temperature. This is because if natural climate cycles are correlated to the time rate of change of temperature, that means they represent heating or cooling influences, such as changes in global cloud cover (albedo).
Such a relationship, shown in the plot below, would provide a causal link of these natural cycles as forcing mechanisms for temperature change, since the peak forcing then precedes the peak temperature.
Predicting Northern Hemispheric Warming Since 1960
Since most of the recent warming has occurred over the Northern Hemisphere, I chose to use the CRUTem3 yearly record of Northern Hemispheric temperature variations for the period 1900 through 2009. From this record I computed the yearly change rates in temperature. I then linearly regressed these 1-year temperature change rates against the yearly average values of the PDO, AMO, and SOI.
I used the period from 1900 through 1960 for “training” to derive this statistical relationship, then applied it to the period 1961 through 2009 to see how well it predicted the yearly temperature change rates for that 50 year period. Then, to get the model-predicted temperatures, I simply added up the temperature change rates over time.
The result of this exercise in shown in the following plot.
What is rather amazing is that the rate of observed warming of the Northern Hemisphere since the 1970’s matches that which the PDO, AMO, and SOI together predict, based upon those natural cycles’ PREVIOUS relationships to the temperature change rate (prior to 1960).
Again I want to emphasize that my use of the temperature change rate, rather than temperature, as the predicted variable is based upon the expectation that these natural modes of climate variability represent forcing mechanisms — I believe through changes in cloud cover — which then cause a lagged temperature response.
This is powerful evidence that most of the warming that the IPCC has attributed to human activities over the last 50 years could simply be due to natural, internal variability in the climate system. If true, this would also mean that (1) the climate system is much less sensitive to the CO2 content of the atmosphere than the IPCC claims, and (2) future warming from greenhouse gas emissions will be small.
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Sphaerica @ur momisugly 3:39
I note you continue to flap your lips and that you still do not show us the effect of CO2 in our atmosphere and oceans. What was all that about ice? Is your next act a photo of an Ice Bear?
Judith Curry herself calls for a new surface temperature record.
=============
The middle got clipped out of the above. The whole thing should read:
Dr. Spencer,
Here’s what I did, using JMP 8.0.2. Using monthly data from 1900 to April 2009 on Hadcrut global temp (not N hemisphere, which data I do not have handy):
1. HadCrut3 temp regressed with PDO, SOI and AMO http://i49.tinypic.com/2vcxpx4.gif
Rsquare is 27%. The Prob>|t| values are <0.05, so all are statistically significant.
The Actual by Predicted plot is skewed from the red line, which means some significant factor is missing from the regression. The Residual by Row plot does not fall on the black horizontal line, which also shows like a significant factor is missing. The way that the residuals go up with time looks very much like much of the temperature increase is missing from the regression.
Leverage plots show that AMO is the most significant factor.
2. CO2 added to the Hadcrut vs. AMO, SOI, PDO regression above http://i46.tinypic.com/whk3mr.gif
This regression is a better fit. Rsquare = 79.5%. As above, all factors are statistically significant.
The Actual by Predicted plot falls on the red line, unlike in 1. and the Residual by Row plot falls on the horizontal line, unlike 1., indicating that adding CO2 makes the model a much better "prediction" of Hadcrut temperature. CO2 appears to predict a whopping 52% of the variation in temperature.
The Sorted Parameter Estimates pink bars show that CO2 is the most significant factor, followed by AMO, and the Leverage Plots give a similar result.
So:
A: What's "wrong" with MY analysis? (Besides the fact that no statistical model proves correlation.)
B: Why shouldn't we interpret this as showing that CO2 is a stronger predictor of global temp than SOI, AMO and PDO?
C: What happens to your model when you add in CO2? Does it then dominate your regression?
D: Tsfc means "surface temp"?
E: What tool did you use to get that "Correlation vs Lag" plot and where can WE get one? Interesting!
F: If you tell me what lags to use, I can go back and redo the whole thing with the lags.
Hope the middle doesn't get clipped again. Saving to Word just in case
That should read “no statistical model proves causation“, not “correlation”.
As the kids are wont to say: “Awesome, man, just awesome!” ☺ ☺
/dr.bill
Yes. (After including my insertion.)
And Freeman Dyson.
sphaerica says:
June 8, 2010 at 3:47 pm
“No, what Spencer has shown is that if you watch and see that 2 + 2 = 4, then you can create a model where 2 is the first input, and 2 is the second output, and look, amazing, 4 is the result.”
No, that is not at all what he has shown. But, you have vanquished my hope that I could make you see.
“As a side note, generally engineers or retired ex-engineers should not try to to apply their training to every single problem they see. “When all you have is a hammer, every problem looks like a nail.”’
I don’t even know what you are trying to say here. All I can surmise is that it’s a shovel of snark to divert attention when you’ve found yourself in a hole. My advice: stop digging.
JBAR,
“What’s “wrong” with MY analysis?”
It looks like you fit all the data, and didn’t use the statistical relationship of CO2 to temperature prior to 1960, to see how good its fit would be for the last 50 years of data. If so, it is not directly comparable. I’d be particularly interested in how well it projects the rest of the mid-century cooling. We’d expect some improvement from adding CO2 overall, since its direct effects would account for perhaps 30% of the warming. But I doubt it explains the cooling or the slope of the recent warming well.
Richard S Courtney says:
June 8, 2010 at 3:44 pm
Okay, first, simply disagreeing with you is not “trolling.” Use the term properly, and respect other people’s opinions.
Second, your unbearably long monologue was so full of exaggeration and conjecture as to be useless. Little of what you said matters to anyone who understands the issues. It was pretty much just empty words.
Fact: the real alarmists are the ones who keep claiming that mitigating CO2 emissions will destroy the world’s economies, or that there is no reason to change anything. Between CO2, peak oil, environmental disasters, and the fact that the rest of the world holds most of oil reserves, there is every reason (economic, ecological, and strategic) in the world to start to pursue renewable energy sources, and even Anthony Watts knows this (he drives and sells electric cars, doesn’t he?).
Grow up. You can’t live by simply telling anyone who disagrees with you to “shut up.”
Bart says:
June 8, 2010 at 6:33 pm
sphaerica says:
June 8, 2010 at 3:47 pm
Funny… I could say the same.
One more time: Correlating temperature increases to temperature increases is a pointless exercise, and it’s all that Dr. Spencer has done. It’s like saying the sun comes up every day because the sun comes up every day. No matter how fancy you make it, and use oscillations and indexes and whatever, you’re not actually doing anything.
Please revisit this thread in ten years, when temperatures have continued to climb, and all of the years from 2010 to 2019 are warmer than 2000 to 2009. Then explain to your children or grandchildren how you were part of messing up the world for them, so that they have no chance of living the lifestyle that you’ve enjoyed, because you were too selfish to think ahead and use limited resources in a reasonable fashion.
Sphaerica says:
June 8, 2010 at 9:54 am
Dr. Spencer,
Various web sites define these indexes as:
The PDO Index is calculated by spatially averaging the monthly sea surface temperature (SST) of the Pacific Ocean north of 20°N.
The Southern Oscillation Index (SOI) is calculated from the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin.
[Note that air pressure is dependent upon, and therefore a proxy for, temperature.]
The AMO signal is usually defined from the patterns of SST variability in the North Atlantic once any linear trend has been removed.
So what you’ve done is to correlate, um, temperature to temperature. And you found a close correlation! Well done!
Now kindly use this to predict future temperatures. Please extend your graph and your model to predict temperatures through the year 2060. Oh, wait, we have to wait until 2060 to do that, so that you have the temperature readings with which to predict the temperature readings.
Also, kindly explain the mechanism (other than hand waving, magic, and climate gremlins) that is actually causing the warming. You’ve described it. You’ve quantified it. You’ve “predicted” it based on a correlation to three temperature based indexes. But explain it. How does a planet with a relatively stable climate suddenly, dramatically warm?
——————
I suppose there isn’t anything very revealing about showing that some indexes based on temperature correlate with an index of temperature, other than the agreement.
It would seem to me that this is precisely what you have been doing. A little projection there, perhaps? Your rabid protestations to the contrary, your behaviour is quintessentially that of a not-very-practiced troll. You advise me to ‘grow up’ while you rave on like an undisciplined 8-year old in the back seat of the family car. You should also be aware that people eventually just quick-scan your posts for random examples of stupidity to add to their amusement files, chuckle a bit, and move on. You’re killing your own misguided cause.
I certainly hope that you are doing all of this in a professional (i.e. remunerated) capacity. If so, however, your employer isn’t getting much in the way of a return on investment. There are much better trolls roaming the web. Some of them are regulars here. You should study their posts a bit. At times they are quite subtly misleading, which is mark of the master-troll. Your own efforts have been quite amateurish so far. If you aren’t being paid, and really believe all that nonsense, then I would advise a change of therapists. The current one isn’t helping.
/dr.bill
sphaerica says:
June 8, 2010 at 9:16 pm
One more time: Spencer has shown that, when you account for the phasing of the various natural indices, they interfere constructively in a way which accounts for at least a significant portion of the recent warming. Honestly… stop digging. You’re in deep.
Please revisit this thread in ten years, when temperatures have cycled back to what you consider “normal”, and all of the years from 2010 to 2019 are coolerthan 2000 to 2009. Then explain to your children or grandchildren how you were part of a movement to deny them the blessings which you enjoyed in life, and to inflict death and suffering upon millions in the Third World.
Actually, I’d bet dollars to doughnuts you will be explaining to them why you are now hitching a ride on the budding “Global Cooling” bandwagon, and that they need to deny their children and grandchildren the blessings which they enjoy because you are frightened about things which you do not understand, and so should they be, too.
I should have said, “when you account for the phasing of the climate patterns associated with the various natural indices…” Maybe that will make it clearer, but I’m not sanguine about it.
Sphaerica says:
June 8, 2010 at 12:52 pm
phlogiston says:
June 8, 2010 at 11:24 am
Reasonable extrapolation of Dr Spencers model forward based on the PDO, AMO and SOI trends probably predicts a temperature downturn. A successful forward (as opposed to backward) climate prediction will also be something beyond their experience.
You missed the point (why am I not surprised). It’s not possible for this model to predict temperatures, and any “successful forward climate prediction” as you call it is not possible with his model, because his inputs are the temperatures. His inputs are the PDO, AMO and SOI indexes, which can only be determined after they happen, and are themselves readings of sea surface temperatures.
Here’s the point that you are missing: phenomena like the PDO, AMO and SOI are cyclical. This means that they increase and decrease in a repetitive and somewhat predictable way. OK they are not like astronomic orbits, there is some variation and irregularity but they do approximate to sine waves on century scales. We are not talking about a random walk or a noise signal.
Your assertion that there is zero possibility to predict development of PDO, AMO, SOI for a few decades ahead, your failure to understand that these are cycles, is truly astonishing.
The average temperature of the ocean is 5C. It has hundreds of times more thermal mass than the air.
We’re basically at the mercy of the mixing rate between warm shallow surface water (16C, 10%) and the vast cold deep (4C, 90%). If it mixes too fast – booyah! – bye bye interglacial, hello ice age. There’s nothing puny man can do to warm the deep ocean and unless that gets warmed it’s a giant heat sink inevitably sucking us towards glacier city.
Dr Bill,
Sphaerica has offered a differing view – a sensible one imo, one worth looking at. For that he has been repeatedly called a troll.
Your post is full of nasty little jibes (three uses of the word troll (in case we miss it?) an accusation he’s stupid, under medical care, being paid to post here, that he’s both a ‘master troll’ and ‘amateurish’) – I guess it will be that he’s a communist next, or knows ‘Gore’?
Can Sphaerica’s cricitc really do no better than such Monckton like attacks?
Doctor Spencer,
I had to sleep on this to realize what a naughty scientist you have been. Very naughty indeed.
You chose to use the rate of change of temperature to do your correlations. But what happens when you take the derivative of a straight diagonal line? You get a horizontal line. By taking the derivative of temperature you are removing most of the increasing long term temperature trend and focusing mostly on the variation around that trend. In your derivative, the long term trend rate of change is roughly zero from 1900 to 1920, +0.02C/year from 1920 to 1940 and zero again from 1940 to 1960. Meanwhile the annual rate of change jumps around from about -0.4 to +0.4C/year. You are correlating AMO, SOI, and PDO with natural variation, not with the long term trend, and of course they correlate very well with natural varation around the trend.
That is also why when I do my regression of temperature vs AMO, PDO and SOI only (Jbar June 8, 5:40PM), my residuals show that something that causes a steady rise in temperature over the 109 years is missing from the regression.
But why does your regression “predict” a rising temperature from 1960 to 2000 at all? In my studies, I have found that CO2 alone does not give a great fit to the long term trend: http://i45.tinypic.com/id664g.gif It is apparent from this plot that there are some multi-decadal variations which CO2 does not “predict” or fit. However, when you regress the AMO and CO2 vs. temp: http://i50.tinypic.com/2a24ok.gif That fits the long term trend much better than CO2 alone.
But let’s take a look at AMO by itself: http://i46.tinypic.com/34q23on.gif AMO doesn’t correlate with the long term trend but you can see there are periods when the AMO trend appears to match with the temperature trend – flat and flat, rising and rising, including the rising 1920-1940 period which Dr. Spencer regressed. (It is my conclusion that the long term temperature trend is attributable to BOTH CO2 and the AMO. In the last 30 years warming, AMO and CO2 were both rising, and so the AMO boosted the warming rate above what it would have been with CO2 alone.)
So what happens when you regress only AMO, PDO and SOI with temperature or temperature rate of change (and as we have seen the AMO correlates with the multidecadal temperature swings)? Why, you are forcing your regression to attribute ALL of the long term trend to the AMO (because you have deliberately left CO2 out). That is why Dr. Spencer’s model does such a good job of predicting rising temperature after 1960. However, I am convinced that if Dr. Spencer did a regression against ALL available variables including CO2 (instead of “cherry picking” only three), then his regression would put CO2 in its proper place as driving the very long term trend while the AMO would assume its proper place in driving much of the multidecadal variation and boosting the recent warming.
Skeptics take heart. The data suggest that the AMO topped out around the year 2000 and may now be in a flat trend. If my hypothesis is correct, that should mean that the rate of temperature increase should slow for some time because the AMO trend is no longer assisting CO2 in raising temperatures. Perhaps that explains why global temperature has appeared (to some) to be flat for the last decade? Ultimately the AMO will start falling, and that should reduce the warming trend even more.
Peter H-
Or it could mean that Dr. Bill knows that Sphaerica lives in lower Michigan, to whom the people in the Upper Peninsula refer to as “trolls”.
Round One @ur momisugly 9:16 PM
Flap, flap, flap. You are all bluff. Show me the effect of CO2 in our climate system.
And listen, we are sick and tired of the guilt trips from the AGW people. Encumbering carbon will necessarily raise the price of energy and diminish the lives of all people going forward, including your and my grandchildren. The AGW paradigm constitutes a war on the poor of this earth, and that is why Copenhagen collapsed.
So please, enough of your fearmongering and trolling. Flap, flap, flap. Show me.
=======================
Jbar says:
June 9, 2010 at 3:50 am
Ultimately the AMO will start falling, and that should reduce the warming trend even more.
A falling AMO might even result in a negative warming trend. Instead of “negative warming”, you could even call it a c.. c..c.. c.. c.. a c.. c.. c… c.. a – OK negative warming will do fine.
phlogiston says:
June 9, 2010 at 12:42 am
Fine… try it. Please produce for me a simple projection of the PDO, AMO and SOI into the future. If they are regular and predictable enough then that should be easy.
But you can’t, because they’re not.
Okay, now with your projected PDO, AMO and SOI, do it. Apply them to the model to predict future temperatures. It seems to me that such an exercise would be not only trivial (if you think it’s possible), but a hugely important part of Dr. Spencer’s post.
So why hasn’t it been done?
dr.bill says:
June 8, 2010 at 11:28 pm
Okay, let’s put this to the test. I have 15 posts on this page before this one, and I see about 25+ posts referencing my posts.
Now go through my posts and find the abusive name calling, and anything which was unnecessarily vitriolic. Quote the text, and cite the posts they came from (by time posted).
Now, to be fair, because you are a skeptic and you don’t just work from preconceived notions, go through the referencing posts, and quote the text and cite the posts that are abusive of me, or unnecessarily vitriolic.
Next, interweave these to see which came first, and who endured how much abuse before snapping a little (as well as how much).
Finally, you can come up with a scorecard of abusive and inappropriate comments; Sphaerica vs. WUWT regulars.
Of course, make sure that you are fair. You are a skeptic. You approach things with an open mind, trying to get to the truth, not with an agenda and a predetermined result that you are going to prove, no matter what the cost.
Do the work and let’s see what the result is.
Round One @ur momisugly 5:32
You called my initial post uncivil and unnecessarily vitriolic, when I was pointing out that you were bluffing about the effect of CO2. You have thrown guilt trips which bounce back into your face. You cover your vitriol with honey but you don’t fool any of us; you are fundamentally uncivil.
=====================
phlogiston says:June 9, 2010 at 12:42 am
Here’s the point that you are missing: phenomena like the PDO, AMO and SOI are cyclical. This means that they increase and decrease in a repetitive and somewhat predictable way.
sphaerica says:June 9, 2010 at 5:18 am
Fine… try it. Please produce for me a simple projection of the PDO, AMO and SOI into the future. If they are regular and predictable enough then that should be easy. So why hasn’t it been done.
Google Joe Bastardi. He has done it, does it, and uses the data to predict.
sphaerica: June 9, 2010 at 5:32 am
Now that’s an improved approach. You are learning already, but I will have to disappoint you regarding your proposed busy-work project for me. (At this point, you should write back and say “Ha, I knew you couldn’t dispute what I’ve said!”, and that will certainly ‘put me in my place’.)
/dr.bill