Multi-Decade Climate Cycles

Since I am a bit late on this, you have probably already seen the stories from NASA that apparently the Pacific Decadal Occilation, which switches from warm to cool cycles every thirty to forty years, has just switched from warm to cool.

The Pacific Decadal Oscillation (PDO) is a temperature pattern in the Pacific Ocean that spends roughly 20-30 years in the cool phase or the warm phase.

In 1905, PDO switched to a warm phase.
In 1946, PDO switched to a cool phase.
In 1977, PDO switched to a warm phase.
In 1998, PDO showed a few cool years.

In 2008, PDO seems to be switching to a cool phase. (NASA).

The warm (cool) phase is determined by above-the-average (below-the-average) temperatures along the West Coast of the U.S. and Canada.

At the same time, a longer cycle occilation in the Atlantic called the AMO may also be in the cooling part of its occilation over the next decades.

Though from what I read, the PDO mainly affects temperatures around the Pacific Rim, the Pacific is in fact  a very large part of the earth, so I wondered if its cylcling might have some correlation with world temperatures:

Pdohistory

Well, that is kind of interesting.  Note by the way I use the GISS surface data in this chart, so one can assume the warming in the last 20 years is overstated for a variety of reasons we have discussed on this site.  Never-the-less, it is interesting.  A few thoughts:

  • Catastrophists are spinning that the PDO cool cycles just delay or suppress man-made warming signals.  OK.  But if you argue this, you have to also argue for the converse — that the PDO exaggerate what might be man-made warming signals during its warm cycles.  Catastrophists and in particular the IPCC, however, said that all of the post 1977 warming was due to man – I don’t remember anyone mentioning "PDO" in these discussions (In fact, they argue that some additional warming was being masked).  Catastrophists love to point to natural cycles only when they can be claimed to mask man-made warming.
  • I am constantly amazed at how much the 1905-1947 trend on this chart looks like the 1977-2005 trend.  But here is the amazing thing to me:  Catastrophists as well as the IPCC claim that these trends had different causes.  In fact, you MUST believe they had different causes to believe the AGW story (since there was little man-made CO2 in the first period).  In other words, to belive the catastrophic man-made global warming theory, you have to believe some effect, presumably natural but never identified by the IPCC, drove temperatures through 1947 and then switched off, never to return, at the exact same moment that man began producing CO2 in earnest.

Update:  It may be too early to tell if the PDO is doing a major or sort of minor shift, but the past frequency seems to indicate we will see a shift soon.

  • Very nice, Warren. The IPCC wants to have its cake and eat it too. As you say, if they claim that CAGW is blunted by the PDO then they have to admit that CAGW is also exaggerated by the PDO. But don’t hold your breath until they do.

    The entire enterprise is an exercise in ad hoc catastrophism, with very little science involved. The backlash from this quasi-religion of CAGW will hurt science as a whole, unfortunately. The bureaucrats and corrupt politicians behind it will probably get a free pass.

  • morganovich

    joe d’aleo did an interesting piece combining the indexes of the ADO and PDO and checking for correlation to US temps. over the last century, the correlation (r squared) was .86. that is a very high correlation for a factor to leave out of post 1977 warming, especially given the very high PDO levels and more frequent el ninos since the super el nino of 1998.

    http://icecap.us/images/uploads/More_on_The_Great_Pacific_Climate_Shift_and_the_Relationship_of_Oceans_on_Global_Temperatures.pdf

  • Like usual, very insightful.

    It would be interesting to see correlation statistics on those two graphs. Also what is the actual slope in the two periods you compare. The recent (1980-present) visually appears steeper.

  • Scientist

    As always, a little glance at the data and the literature would have saved you from looking foolish.

    I don’t remember anyone mentioning “PDO” in these discussions – that’s probably because you’re very stupid. The PDO is discussed at length in the most recent IPCC report.

    I am constantly amazed at how much the 1905-1947 trend on this chart looks like the 1977-2005 trend – what, that it is upward? This is not amazing. Only the simple-minded would find it so. Did you notice the difference in gradient, though?

    In fact, you MUST believe they had different causes to believe the AGW story (since there was little man-made CO2 in the first period) – no. By 1947, the CO2 forcing from the pre-industrial baseline was +0.6 W/m². The CO2 forcing today relative to 1947 is +1.1 W/m². Why don’t you ever do such simple checks? Probably because you have no interest in science, only your own small minded politically paranoid outlook.

    some effect, presumably natural but never identified by the IPCC, drove temperatures through 1947 – quite obviously you have never gone to the bother of reading up on this. It’s very well established that solar changes were a significant contributor back than. It’s very well established that CO2 is now a more significant driver of climate change than solar variations. Papers by Solanki et al are a good place to start learning. But I don’t think you’re too interested in learning.

  • dreamin

    Ahhh . . . the sweet smell of epicycles.

  • Josh

    What’s interesting is that the slope from ~1910 to ~1943 is ~1.6*/C, and the slope from ~1975-~2004 is ~1.8*/C (that’s degrees/century). Assuming 100% of the variation from 1910-1943 is natural, then global warming added a whopping 0.2 degrees PER CENTURY to that. And notice that there is a downward trend before 1910 that matches the downward trend between 1943 and 1975 (it’s more obvious in the HADCRUT data which goes back to 1850 than in your chart above). And what’s even more interesting is the time – 1910-1943 is 33 years; 1943-1975 is 32 years; 1975-~2005 is ~30 years. What an amazing coincidence that it got cold for some unknown reason for ~30 years starting around 1880, then the sun turned on for exactly 30 years and made it warmer, then aerosols kicked in for exactly 30 years and made it cooler, then AGW kicked in for exactly 30 years and made it warmer, then…

    I think they got going with this “radiative forcing” idea and decided it explained everything about global temperature. When it broke down they added new forcings. It reminds me very much of string theory where every time something isn’t explained by string theory, they add another dimension. When you can keep adding terms (forcings/dimensions/epicycles) to explain new observations, you’re just describing symptoms – you’re way off on describing the problem.

  • bill-tb

    But but but, the CO2 forces the temperature to climb. I want my global warming. Is CO2 going down now? My guess is this is just a$$ covering a temporary plug in the leaking hot air hoax.

    The only thing I think CO2 does is raise taxes.

  • Chris Christner

    Scientist, you’re the perfect example why slashdot refers to those who post anonymously as “anonymous cowards”: you hide behind anonymity while calling people “stupid,” “foolish,” “very stupid,” “simple-minded,” and “paranoid.”

    I usually ignore your postings because you don’t treat others with consideration. This comment probably won’t change anything because you appear to enjoy slandering total strangers, but what the heck, how about acting towards others as if you weren’t anonymous? Do your karma a world of good.

  • Don’t … feed … the … troll!

    Actually a bit of slashdot-style comment moderation would be pretty useful on this blog, I have to say…

  • Industry Insider

    Scientist wrote: “In fact, you MUST believe they had different causes to believe the AGW story (since there was little man-made CO2 in the first period) – no. By 1947, the CO2 forcing from the pre-industrial baseline was +0.6 W/m². The CO2 forcing today relative to 1947 is +1.1 W/m². Why don’t you ever do such simple checks? Probably because you have no interest in science, only your own small minded politically paranoid outlook.”

    I observe: So the CO2 forcing delta in 1947 was +0.6 W/m2, which was followed by 30 years of a flat to decreasing temperature trend. Too busy to look it up this morning, but what did the CO2 forcing delta look like around 1915 when the increasing temperature trend started? I would expect the delta in 1915 was a lot less than +0.6 W/m2 (a value that did not cause increased temperatures in 1947), and we see a steep temperature increase from around 1915 through 1945. This does not seem to indicate that CO2 was driving the climate.

  • Samuel Pickwick

    In the above graph the 1970-2000 slope looks marginally greater than the 1910-1940 slope. But that is because it is the Hansen-doctored data, where data is constantly revised retrospectively, always in the direction of increasing the slope, as reported widely here and elsewhere. If you look at the HADCRUT3 graphs there is no discernible difference in the slopes.

    This latest garbage from the catastrophists is in direct contradiction with the IPCC, which says that ‘most of the observed increase … is very likely due to anthropogenic GHG’. Now they seem to be claiming that natural fluctuations are of the same magnitude, in order to cancel out, so half of the warming must have been due to the natural oscillations.

  • To be sure, CO2 does add some forcing. The amplitude of that forcing must now be questioned. If we are moving from a warm PDO regime to a cool one, and the cool regime is now masking the AGW effect, then indeed, we must ask questions about the warm PDO regime enhancing the CO2 AGW effect from 1980 to 2000.

    If CO2 is so powerful, as we are led to believe, how can it now be “masked” by a cool PDO when it obviously (to the alarmists) wasn’t enhanced by a warm PDO?

    I guess the take-home lesson is that increases in temperature are caused by humans and are, therefore, catastrophic. Whereas cooling is simply a cyclical masking of the AGW signal.

  • mbabbitt

    Scientist: You stated in another thread (using name calling as an argument technique) that warming is still occuring and gave a link to RealClimate to demonstrate this. Well, Mr. smarty pants, look at http://www.theregister.co.uk/2008/05/02/a_tale_of_two_thermometers/, which shows the problem in how data collected by NASA is being displayed in a way that makes it appear that we are warming dramatically. But there is another side to the story. Other temperature trends show stagnation and even cooling. I think that article encapsulates the entire debate and the point of the writer is well-taken: Isn’t there a conflict of interest when the AGW promoters create the models, select the data, and then interpret the data, And then tell the world how their science shows severe AGW? In auditing the separation of duties is an essential part of ethical corporate governance. In the climate science world, this essential practice is ignored to the peril of our economy — and sanity.

  • Mesa Econoguy

    It’s very well established that solar changes were a significant contributor back than.[sic.] It’s very well established that CO2 is now a more significant driver of climate change than solar variations.
    Posted by: Scientist

    Oh, really?

    http://www.heartland.org/NewYork08/newyork08.cfm

    Go fuck yourself, amateur dumbass. And your bullshit “consensus.”

  • Andrew

    Now now, no need to be rude. Just becuase you disagree with that statement (and many would) doesn’t mean you should tell him to “go f***” himself. Listen to the wise poster above who said, “don’t feed the troll”.

  • Mesa Econoguy

    Basing a movement to steal private property and stifle economic activity/wealth creation on fabricated and statistically bogus CO2 “studies” is basis for verbal abuse, at minimum.

    People like this “scientist” socialist pig showing up at my door propagating their claptrap can expect physical violence as well.

  • I may just be too hopeful, but…

    I think that the Global Warming Hysteria Index has peaked, and the short sellers are now in control.

    It seems like every time a climate scientist retires (and hence is safe from retaliation), he publishes a book taking issue with AGW. People are starting to notice.

    PLUS…

    There is a silver lining to the big black peak oil cloud (if that is what we are seeing). It will cause enough pain that ordinary people will send these climate alarmists running (to escape the tar and feathers). Then we can start using our huge reserves of coal, build some nukes and get out of the energy hole.

  • Steve

    I just went to http://www.heartland.org/NewYork08/newyork08.cfm and found a graph of AMO + PDO, then scaled it and superimposed it on the temperature graph from this post. Amazing! it matches almost perfectly!

    And it looks like high temperatures in the 30s and late 90s is when the PDO and the AMO coincide.

  • kuhnkat

    Scientist says that PDO was discussed all through IPCC 4.

    OK, I’ll bite Scientist. So please show us how it is built into their models??

    Oh yeah, they didn’t do any model runs predicting the current PDO temp stagnation or cooling until AFTER the PDO went NEGATIVE!!

    Scientist, does that include the AMO that may be going negative also??

    In a couple years are they going to include the lower solar output we are currently experiencing??

    Hey, I bet you could model the earth’s climate for us too, IN HINDSIGHT!!!

    HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA

  • Scientist

    Assuming 100% of the variation from 1910-1943 is natural – bad assumption.

    Isn’t there a conflict of interest when the AGW promoters create the models, select the data, and then interpret the data, And then tell the world how their science shows severe AGW? – no, I don’t think there is a conflict of interest when scientists do science.

    Too busy to look it up this morning, but what did the CO2 forcing delta look like around 1915 when the increasing temperature trend started? – being an overt disbeliever when you haven’t done basic research is foolish.

    I would expect the delta in 1915 was a lot less than +0.6 W/m2 – why would you expect that when you haven’t done any research? You are wrong. Do you know what logarithmic curves look like?

    (a value that did not cause increased temperatures in 1947) – replace did not cause with contributed to and your statement is correct.

    And it looks like high temperatures in the 30s and late 90s is when the PDO and the AMO coincide. – why, then, were 1990s temperatures about 0.5°C higher than 1930s temperatures?

    General note to all: if you think the Heartland Institute or the Register are reliable places from which to inform yourself about science, you’re a fool.

  • Industry Insider

    Scientist writes:

    “Too busy to look it up this morning, but what did the CO2 forcing delta look like around 1915 when the increasing temperature trend started? – being an overt disbeliever when you haven’t done basic research is foolish.”

    I respond: Characterizing someone’s actions as foolish is not productive – let’s be civil in our discussions. And you still did not answer my question.

    “I would expect the delta in 1915 was a lot less than +0.6 W/m2 – why would you expect that when you haven’t done any research? You are wrong. Do you know what logarithmic curves look like?”

    I respond: Then please tell me the correct answer. If I am wrong, I will admit it.

    “(a value that did not cause increased temperatures in 1947) – replace did not cause with contributed to and your statement is correct.”

    I respond: Some revised language to better convey my point: “(a value that did not result in warming during the 30-year period after 1947)”

  • Scientist

    I think that taking a position on an issue without doing research on it is not productive. It takes a matter of seconds to calculate forcings from CO2 concentration changes, if you know the equations. You really should do basic research before deciding what your opinion will be. If you don’t wish to do research, or don’t have time, then you should not even be forming an opinion, let alone publicly espousing it. But if you want me to do the work for you on this, then here we go.

    Take the base CO2 concentration as 283.4ppm. One equation for calculating forcing is ΔF = 5.35ln(C/C0) where C0 is the reference concentration. In 1915, the concentration of CO2 in the atmosphere was 301.4ppm. In 1947 it was 310.2ppm. The forcings are then.. well, do you want to do the calculations?

    What you can then go on to calculate is the expected climate response, if these CO2 forcings were the only forcings operating, and if the climate system was given enough time to reach equilibrium. The climate sensitivity is generally estimated at about 0.75°C/W/m². What you should find is that the temperature changes are not huge. Other effects are comparable. The solar constant increased by about 0.8 W/m² between 1920 and 1945, giving a forcing of 0.14W/m². You can calculate the forcing due to the change in CO2 concentrations over the same timescale. Is it larger or smaller? What would the expected climate response be from solar forcing in isolation?

    Now, do you think that CO2 concentrations are the only factor in determining global temperatures, or do you think that anyone in climate science thinks this? It appears that you must, from your statement that the CO2 forcing did not result in warming during the 30-year period after 1947. I suggest you look up a TSI reconstruction so you can estimate the solar forcing over this period, compare that with the CO2 forcing, and also consider the effect of volcanoes and anthropogenic aerosols over that period. How much do you think temperatures should have changed by? How much did they actually change by?

  • Industry Insider

    Scientist – I appreciate the detailed response. Using the equation you specify, ΔF(1915) = 0.329 and ΔF(1947) = 0.483, so the delta in 1947 is 47% higher than the value in 1915 (and 47% is “a lot” higher in my opinion). Regarding the rest of your post, I am not discounting the other factors that determine global temperature. (Rather, I was making the point because there is a perception out there in the public that all of the temperature change since pre-industrial times was caused by CO2, which I think we both agree is not the case.) As I have said before, while CO2 can affect climate, I believe that effect is less important than other factors, particularly in light of the information discussed here recently regarding the various feedbacks and decadal oscillations.

  • Scientist

    And following the forcing calculation with a temperature calculation, using 0.75°C/W/m² you get 0.25°C and 0.36°C. The difference is 0.1°C; this is well within the range of interannual variation that is caused by internal variability. It is not a great surprise that this rise in CO2 forcing did not lead to an uninterrupted rise in temperatures; other factors can easily offset that forcing. The forcing today relative to 1850 from CO2 is about 1.7W/m², and this forcing is now the largest operating.

    The effect of oscillations averages out to zero, by definition. You cannot explain the secular upward trend in temperatures by recourse to these oscillations. The current rise in temperatures of about 0.2°C per decade is exactly in line with expectations given the rising concentrations of CO2 and the smaller effect of all the other forcings.

    Which factors do you believe are more important than CO2?

  • And as temperatures continue to drop, we find CO2 changing from positive forcing to a negative forcing. Of course GISS will continue faking temperature readings as long as it can, but such humbuggery can only last so long in a modern world.

    When the modelers finally begin to realize they have been doing their calculations based upon humbuggered data, it will be time for the fat lady to sing.

  • Industry Insider

    To believe there is a current rise in temperatures of about 0.2 C per decade, one has to believe the various adjustments to the temperature record are valid, and I note that there are some well-founded doubts about that. It is clear that non-CO2 factors are driving the climate system because temperatures are not increasing. The past 10 years of temperature data and projections for the next 10 years illustrate the importance of the non-CO2 factors (e.g., solar factors and oscillations) as the primary determinants of global temperature. As has been discussed ad nauseam here and elsewhere, in order for CO2 to result in large, catastrophic temperature changes, the climate system would have to be dominated by positive feedback mechanisms (meaning the sum of the various positive and negative feedbacks would be positive and large), and we are not seeing the evidence for that in the real world.

  • Scientist

    No, there aren’t well-founded doubts. None appear in the scientific literature, although of course you will find no shortage of politically motivated, scientifically questionable blogs on the subject. In reality, whether you look at GISS data, Hadcrut, RSS or UAH, there is a warming trend over the last thirty years of 0.15-0.2°C/decade.

    Temperatures are not increasing? What makes you think that? Which data set shows this, and over what timescale?

    Yes, we do see the evidence of positive feedbacks in the real world. Northern polar regions are warming far more rapidly than anywhere else, due to one particular feedback. Ice ages could not occur without positive feedback, and they could not end without it either.

    It looks very much like you are taking a position which is not based on the evidence. Simple numbers show that CO2 forcing dominates. I do not see you showing how any other forcing is currently comparable to CO2 forcing, or arguing that my numbers were wrong, I just see you vaguely stating some misconceptions which find no support at all in the peer-reviewed literature.

  • Mesa Econoguy

    Note to all:

    Peer reviewed AGW “science” is meaningless.