Doug L. Hoffman
Friday, Dec 18th, 2009
While climate skeptics have gleefully pointed to the past decade’s lack of temperature rise as proof that global warming is not happening as predicted, climate change activists have claimed that this is just “cherry picking” the data. They point to their complex and error prone general circulation models that, after significant re-factoring, are now predicting a stretch of stable temperatures followed by a resurgent global warming onslaught. In a recent paper, a new type of model, based on a test for structural breaks in surface temperature time series, is used to investigate two common claims about global warming. This statistical model predicts no temperature rise until 2050 but the more interesting prediction is what happens between 2050 and 2100.
David R.B. Stockwell and Anthony Cox, in a paper submitted to the International Journal of Forecasting entitled “Structural break models of climatic regime-shifts: claims and forecasts,” have applied advanced statistical analysis to both Australian temperature and rainfall trends and global temperature records from the Hadley Center’s HadCRU3GL dataset. The technique they used is called the Chow test, invented by economist Gregory Chow in 1963. The Chow test is a statistical test of whether the coefficients in two linear regressions on different data sets are equal. In econometrics, the Chow test is commonly used in time series analysis to test for the presence of a structural break.
A structural break appears when an unexpected shift in a time series occurs. Such sudden jumps in a series of measurements can lead to huge forecasting errors and unreliability of a model in general. Stockwell and Cox are the first researchers I know of to apply this econometric technique to temperature and rainfall data (a description of computing the Chow test statistic is available here). They explain their approach in the paper’s abstract:
A Chow test for structural breaks in the surface temperature series is used to investigate two common claims about global warming. Quirk (2009) proposed that the increase in Australian temperature from 1910 to the present was largely confined to a regime-shift in the Pacific Decadal Oscillation (PDO) between 1976 and 1979. The test finds a step change in both Australian and global temperature trends in 1978 (HadCRU3GL), and in Australian rainfall in 1982 with flat temperatures before and after. Easterling & Wehner (2009) claimed that singling out the apparent flatness in global temperature since 1997 is ’cherry picking’ to reinforce an arbitrary point of view. On the contrary, we find evidence for a significant change in the temperature series around 1997, corroborated with evidence of a coincident oceanographic regime-shift. We use the trends between these significant change points to generate a forecast of future global temperature under specific assumptions.
Read the rest of the article here.
I predict the temperature will rise 20 degrees by 2010 … plus or minus 100 degrees. There, now on to the stock market.
“”” Richard Sharpe (15:48:22) :
George E. Smith (15:13:23) says:
It might be useful to note that the last time that atmospheric CO2 levels were as low as they are today, was about 267 million years ago; go figure.
Hmmm, however, we are told that before the industrial revolution they were lower than now. “”
Very true Richard, but since it is a well known fact that global mean temperature varies as the log of the CO2 atmospheric abundance (Steven Schneider of Stanford University says so), then the change since the industrial revolution in CO2 is nowhere near enough to make a hill of beans worth of difference; and we know that life on earth survived that 7000 ppm we used to have; or 20 times what we have today. And the change from pre-industrial to now, is quite consistent; even robustly so with natural variability.
So nothing to see here; move along now.
Let me get this straight, first they said that the equator would warm up BEFORE the polar region. OH, sorry, we got that wrong, BUT CO2 is the cause and we see the polar region heating up more than the equator. Not to worry, the basic model is correct….
OK, so the model says RAPID WARMING is around the corner and will hit us very soon. Oh sorry, that was off, in the last 11 years we had to “Hide The Decline” and the last 4 years the Earth is cooling… Not to worry, CO2 is bad and our basic model is correct…
Minor corrections guys, not a whole lot of changes until 2050 guys… AND this time OUR MODEL IS BANG ON CORRECT, trust us 100%!!!!!
If these guys making the model become financial advisers and tell you where the market is going, I would STRONGLY advise you find someone else…..
😉
This is just a typical piece of research. It has no falsifiable prediction within the working life of anyone, but is intellectually entertaining. With a slightly different set of initial assumptions, it would show a secular decline after the equilibrium period.
If this actually represents the “best effort” of the AGW community to rationalize a substantial NH cold spell, that position is tenuous.
For a buck, I will forecast anything you want for the year 2065. Not only that I will guarantee that the forecast will come true in 2065 with my entire savings, my house, and my very life.
Please do not look up the year of my birth before sending me the buck.
So this is a paper based on the presumption of linear trends in climate?
How do people get paid for writing such rubbish?
Sandy asks, “How do people get paid for writing such rubbish?” Sandy is obviously talking about these people:
http://sciencespeak.com/ClimateFunding.pdf
Ahhh, the Chow test. That’s when you make a dog’s breakfast of unsavory data spiced with statistical tricks….. Served hot to the gullible.
Models are simply explorations of the consequences of assumptions. Here the idea was to represent the more non-linear aspects of climate behaviour, sudden breaks. The assumptions, such as the existence of breaks, the alternating and considerable time between them, and an underlying warming rate of 0.5C/century are supported by a host of other physically based studies. This is a linear projection, elaborated by some breaks, justified both statistically and by physical studies.
Most of the assumptions a fairly plausible, with the most uncertain being that another break up is not expected until around 2050. The current period is an analog of the period from the 1930s to the 70s.
You can also click on:
Will 2010 be warmer than 2009?
Will 2019 be warmer than 2009?
Will 2019 be 0.2 degrees warmer than 2009?
astonerii (13:25:00) :
I read this a few weeks back. While it seems to have a good outlook, something that bothers me is the durations of future flat/cooling and warming trends. If you look over the past few trends, they had durations of around 30 years, and these guys are looking at 40 and 50+ year trends.
The Atlantic Multi-decadal Oscillation (AMO) has a period of 60-80 years. So warm for 30-40 years and then cold for 30-40 years. So OK, maybe….
The approach (Chow test) divides the data up into sections. See http://en.wikipedia.org/wiki/Segmented_regression
Within a section, the linear fit is good. The significance of the fact that the temperature anomaly data can be segmented is stated in the paper.
“… because the slope of the two segments is not significant (p=0.15 and p=0.14), any trend due to increasing CO2 is statistically insignificant.”
Stockwell and Cox are not trying to explain why the data is segmented but rather demonstrating that the temperature anomaly data is segmented and therefore that CO2 is not a significant factor.
Have to give E.M.Smith credit for taking a fresh look at climate analysis. Looks like I’ll have to reconfigure my Tradestation program for climate change analysis.
Great Post!!
Roger Knights (15:07:14) “These warmists can’t conceive of a “bend” […]”
That’s exactly what makes them appear as bold-faced liars.
Thanks Mike. If a physical intuition helps, the model is composed of an underlying warming trend of 0.5C/century (that one could attribute to CO2), and two phases, a ‘cool’ phase which more efficiently dissipates heat than a ‘warm’ phase. The ‘cool’ phase just manages to keep the surface temperature constant, but the ‘warm’ phase is less efficient. Why this happens (why PDO and AMO) is speculative, and so not in the paper, but I suspect there is a natural resonance with a period determined by the path length of the ocean currents, and non-linear ‘energy capture’ can explain why the amplitude of natural variation exceeds that of the measured external forcings. Wacky? Not really. All well known physical principles.
I try not to predict the future until it has happened. That way I am never wrong, unless I get my story from tv, the radio or the press.
For those of you who don’t trust economists or the organizations they head…
and also for those of you who want a zippy comeback line when an AGW believer claims that an economist like Dr. Ross McKitrick has no right to argue climate change with a “climate scientist” like Dr. Rajendra K Pachauri…
Guess what… Dr Pachauri has no climate science degree, but he does have a PhD in economics… just like Dr. McKitrick. See http://www.climatescience.gov/Library/bios/pachauri.htm (yes, a US government website) for Dr.Pachauri’s CV.
First, thank you, Anthony for this great website. It has been for me as a layman a good jumping point for the literature regarding the great debate. As for this prediction and others like it they are not very useful bordering on the laughable. I do have one question for you, I have looked far and wide, what is the evidence of a corelation between climate warming and CO2 levels?
Thanks,
Grant
Sonia, Ca.
And how does their model model the whole Holocene with its ups and downs? Lots of trends there :http://www.foresight.org/nanodot/wp-content/uploads/2009/12/histo3.png
We are just a part of the holocene. If they cannot model it, waste bin it.
It is good to have a look at the full record of known temperature changes, now and then : http://wattsupwiththat.files.wordpress.com/2009/12/noaa_gisp2_icecore_anim_hi-def3.gif
to keep the perspective.
http://www.foxnews.com/scitech/2010/01/06/extreme-weather-mother-nature-gone-bonkers/?test=latestnews
There is a limit to civility.
Nobody needs to read warming alarmism in widespread bitter cold winter. People are succumbing out there.
Nix the warming causes cooling stuff, ere tempers snap like power lines with too much ice on them.
At least I now know I wasn’t seeing things yesterday when this post showed up briefly on the right-side listing, but when I went to the main page and reloaded it wasn’t there.
Maybe they decided to hold it for a day until it was properly peer reviewed. 🙂
So, and why is it that continuously rising CO2 levels will suddenly stop doing “their job” for the next 50 years?
That alone amounts to admitting that there are other and stronger factors in play.
They need to scrap the whole “CO2 is driving the climate cycles” as a base line. The real climate drivers are the cosmic forces, due to the movement of the solar system, on the trek around the Galaxy.
It would be in error to not consider the 27.32 day cycles of the Lunar declination and the inner planet interactions that generate the yearly patterns, with consideration for the interactions with the outer planets that drive the 12 to 13 month cyclic return episodes, of severe hurricane and tornado surges in global weather patterns, that make up the natural variability.
We will never be able to sort out their compounded signals, if we just look at the larger forces at work as background noise, which greatly overcomes any small CO2 signal that may be there.
Only by looking at the periodicities, in the compound signal and finding the under lying long term compound pattern, where in they repeat on a similar time scale, so they can be looked at, as a complex background pattern of influences, in order to get any kind of model, or forecast that overcomes this background noise.
I have found a background pattern of 6558 days that is one 27.32 day lunar declinational cycle short of a Saros cycle that does a fair job of reducing the ambient noise in the rest of the spectrum. Well enough that it repeats from the past three cycles to this one, good enough to generate a forecast that works for periods out to 15 years in length.
I have posted the composite of the last three cycles, on a web site where they are made into maps, representative of the surface weather to be expected, this time around. The past three cycles were under the influence of high solar activity, where this one is coming in the depths of a longer than normal minimum. So it seems that the differences in the composites, to the actual (in missing some of the deep low temperatures) we are having might just suggest that the difference in solar activity is to blame.
http://www.aerology.com/national.aspx
The data was pulled out of NOAA’s TD3200 CD data set in August, 2007 and tabled, then I started to process the data into grids and maps, which I posted on the site (starting in September 2007) for dates from 2008 through 2013.
No updating of maps, or changing of dates except to adjust for one leap year shift in date, these maps are still the same as I generated them.
In response to the quarry that, “no model has been able to predict the current surge in cold temperatures” I say this one has been better than most with a lead time of over two years to boot. You might want to take a look at how it has preformed over the past year, and how it is still doing now.
As I said earlier the deeper cold temp extremes, that it gets close to but misses the core areas of the cold extremes, I think is a solar minimum feature.
I have discussed this method in several other threads, on this site, and most of what I have had to say about this method, can be found on the web by googling “Richard Holle aerology.”
I think you will find that this new paradigm, answers a lot of questions about the driving forces of the global circulation, and bares further investigation, past the passive Beta strictly cut, copy, paste, make grid, and then map stage of development.
Richard Holle
First it was hockey stick, then worse than we thought, then climbing ever higher, and even higher and now it suddenly plateaus for 50 years… only to continue climbing conveniently later… give me a friggin break, the models are broken, they don’t work, the “science” is broken just admit it.
Is it just me, or would anyb ody feel more comfortable with this “prediction of the next fifty years” … If they had only managed to use the ACTUAL temperature records for the past fifty years, instead of the (mal) adjusted and corrupted (er, adjusted) and massaged records from GISS and HADGRUD?
Confucius say, “One who predicts future must stand firmly in present, but look accurately at past.”
As far as I know, we have no accepted theory that can predict future solar activity. Lacking this may render any prediction of the Earth’s future climate problematical.