Comparing Zonal Trends in the 20th Century

During the 20th century, we’ve seen three distinct global temperature trends:

1) A warming period from 1910 to 1942,

2) A cooling period from 1942 to 1978, and

3) A warming period from 1978 to the present.

The graph below is of global temperature (as collected by the GISS) from 1880.

The warming in the early 20th century is largely seen as natural.  CO2 levels in the atmosphere were not increasing nearly enough for anyone to claim that it caused the extent of warming recorded.  Similarly, the mid-century cooling can’t have its roots in CO2 output, and instead was likely caused by increased particulate pollution and decreased solar activity.  The warming seen since 1978 is what is so contentious.   The purpose of this post is to compare zonal trends during the two warming trends.

Below are two graphs that show zonal trends in temperature during the perid 1910-1942.

Below are two more graphs, representing zonal trends over the period 1978-2007.

As you can see the zonal temperature signal for both periods are nearly the same.  This is important because anthropogenic global warming promoters use the high lattitude warming as evidence for the effect of increased CO2 levels on temperature.  Yet, this same pattern of warming, best demonstrated by the zonal mean vs lattitude charts, was observed during a completely natural period of warming.  There is one notable difference between the trends observed during the two periods, though.  Warming seen in Northern Asia and Europe during the modern warming did not occur during the period of natural warming.  As I see it, there are a few explanations: 1) This Siberian warming has been caused by increased CO2 levels in the atmosphere. 2) The magnitude of the modern warming has been somewhatlarger, which might have caused a warming signal that the smaller, natural warming did not exhibit. 3)  The warming periods are both natural, though they were not caused by the same climate shift.  For example, warming during the first half of the century may have been caused by increases in total solar irradiance, while this modern warming may have its origins in oceanic circulation.  This would result in different regional trends.

So, there are two points to be made about this zonal trend analysis.

1) Arctic warming may be natural.  It has occured before with equal intensity, and thus Arctic warming is not evidence for a CO2 forcing.

2) The two periods of warming are not entirely the same.  The modern Siberian warming that some attribute to rising CO2 levels did not occur during the natural warming.  When I saw Harvard astrophysicist Willie Soon, Ph.D. speak at the International Conference on Climate Change, he attributed this warming to changes in regional oceanic currents.  I am sure that there are other possible explanations, and I may post something about it in the future.

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10 Responses to “Comparing Zonal Trends in the 20th Century”

  1. timetochooseagain Says:

    I’m not sure everyone would agree that warming during the early twentieth century was entirely natural-not saying I think differently but, well, climate is messy like that. The way I see it, several explanations of the high latitude warming come to mind.

    Urbanization-this is obvious, but, it would only operate at the surface, and greater high latitude warming is seen in the atmosphere, too.

    Soot-These areas are more industrialized, or closer to industrialization, than areas in low and SH latitudes, and the warming is atmospheric not just surface.

    The GHE-some skeptics-for instance, Pat Michaels, would tend to point to the Greenhouse Effect. The fact that it does also happen in the SH may be an Ozone Hole effect-I’m iffy on this, but it is probably ~part~ of the reason.

    Of course, these aren’t mutually exclusive, and there maybe a natural explanation (all of mine are technically anthropogenic) and I would never try to make a “Greenhouse of the Gaps” like some people…

    I’m curious about this stuff on Ocean currents-I haven’t read anything about it. definitely worth looking into. 🙂

  2. carlwolk Says:

    I’m sure there are some out there advocating the fact that early 20th century warming was anthropogenic, but most of the focus has turned to the last three decades. A great example of this is practically any AGW believer’s argument against a solar causation; they show how solar intensity follows temperature up until around 1975, and they go on to make the case that warming since 1975 has been manmade.

    About urbanization, it couldn’t really explain the intense 60 degree to 90 degree warming.

    As I said, Willie Soon thinks that changes in oceanic circulation drive Arctic temperatures, but I didn’t mention that he has also rejected the GCR theory, on the basis that as a physicist, he finds it impossible. I’ve been looking for anything he’s written on either of the two subjects, yet I can only find things he wrote in favor of the GCR theory (before he changed his mind). If I can find any papers suggesting that ocean currents drive Arctic temperatures, I’ll make a post.

  3. Andrew Says:

    Well, the ocean currents stuff is interesting. I think that Joe D’Aleo and Bill Gray do stuff with that, so you should check Icecap. BTW, I would not agree with those who say that solar activity no longer correlates with temperature changes-On three grounds. First, that there is more than one TSI data set, one of which, at least, shows a positive trend post 1978-ACRIM. Second, they are (ironically) ignoring the effect of ocean delay in such arguments-according to Scafetta and West, with this effect, you could account for ~at least~ 30% of the most recent warming-though some observations suggest that ocean delay is neglidgible. And last, the ion chamber and 10Be data clearly show that Cosmic Rays decreased ~throughout~ the twentieth century-and the ion chamber data even show an increase during the mid century cool period! I am not sure why Willie Soon has changed his mind on the idea-I certainly know a lot of physicists who don’t find it “impossible”-but I suspect that Willie is bothered by the apparent mismatch between the Hoyt and Schatten TSI model and Cosmic Ray data- he is a big believer in that data, having pointed out how well it correlates with Arctic temperatures. You are probably right about urbanization not account for all that warming-especially since it extends to the atmosphere-however, it is worth noting that there is definitely some substantial contamination. Though it looks like the big biases are in the tropics. There are even cool biases over North America:
    http://www.worldclimatereport.com/index.php/2007/12/22/contaminated-temperature-data/#more-293
    Having read their paper, I also noticed that they noted a powerful effect of adding a “soviet membership” term of their equation-but worried that it eliminated to much of the real warming there. I have to wonder how much Russian warming is due to deliberate fudging of records under Communism-if it was very cold, then the Governmentg might send extra food or something, I think. But after 1990-well, no need to fudge the records colder anymore, bam! Instant warming.

  4. Andrew Says:

    Ah-bingo!
    http://www.intellicast.com/Community/Content.aspx?ref=rss&a=128
    Is this what you mean?

  5. carlwolk Says:

    I’ve read D’Aleo’s blog, though I am particularly intruiged by possible links between oceanic currents and solar variation. A combination of PDO and AMO seems to render 20th century variations that are very similar to TSI variations. Maybe a coincidence, maybe something relevant. (By the way, do you know where I can find the real PDO, AMO, ENSO, etc data?) Over at Climate Audit, someone named Erl Happ has started a massive debate on the Svalgaard thread. His theory is that short, abrupt increases in solar radiation leads to El Ninos, creating a sort of macro view of oceanic circulations as a product of solar variaton. Svalgaard has not taken a liking to Happ’s pet theory, though I really don’t know enough to take a side.
    I didn’t know that 10Be dats show a decrease in GCR bombardment throughout the last few decades. But, is that really the best measure? I know that 14C is used as a proxy because it is created during the atmospheric bombardment by GCRs; is 10Be also created through that process? As far as I know, modern GCR levels are measured by neutron levels at places like the Climax station in Colorado, which shows (of course) intense variations within the past three cycles, but no general upward trend. Neither have low cloud cover and geomagnetic wind intensity. I am rather undecided on the GCR theory, so I have a question. Low cloud cover should have a rather quick impact on temperatures, right? If that’s the case, why is there not a clearer 11 year signal in temperature. If the only solar forcing on the Earth was direct heating, ocean lag time, etc could dull an 11 year signal. Yet, it would seem that the GCR effect would cause a much clearer 11 yea signal. Am I wrong with that statement? Leif Svalgaard (I think) brought up an interesting point at Climate Audit; he pointed out that GCR bombardment actually has a 22 year cycle. If you look at the peaks of the cycle, they cycle between flat and pointed due to something with the changing polarity of the Sun. Do you think this could have any relevance?
    Another interesting note on GCR – Svalgaard’s theory is that solar intensity has changed a lot less than other reconstructions since the Maunder Min (he still doesn’t buy into CO2 forcing). When I responded to the thread, citing reconstructions of solar irradiance/GCR using 14C, he put this picture up: http://www.leif.org/research/14C.png. ….great…more data controversy… What makes it especially great is that no one cares about it enough to provide insightful commentary on it. If you ever find discussion of paleo 14C/10Be data, I’d be very interested to se it.

    About Willie Soon, he wasn’t especially clear about his opposition to the theory. But he essentially said he used be in the forefront of the GCR theory, before he found the mechanisms to be physically impossible and concluded that the data had many problems with it. Afterwards, I talked to him and cited the argument presented in a Svensmark paper that trails of clouds can be found behind large ships emitting aerosols into the atmosphere (thus proving the ionization part of the process). He didn’t really have a response to that. Hehe. Then again, he isss a Harvard astrophysicist.

    Your point about Russian warming is extreeeeemely interesting. I’ll be sure to look into it.

  6. carlwolk Says:

    That’s exactly it! I was just looking at that the other day, though some how I managed to navigate way from it and forget it. By the way, do you buy into, Nir Shaviv’s theory of GCR as the cause of the icehouse/warmhouse (or whatever you call it) cycle?

  7. timetochooseagain Says:

    Ah, ye old “no eleven year cycle” argument. But, if you look at IPCC 2007 page 674 they say that:

    “The peak-to-trough amplitude of the response to the solar cycle globally is estimated to be approximately .1 degrees C near the surface”

    This has been found by various studies. Like this one:
    http://arxiv.org/ftp/physics/papers/0411/0411002.pdf

    As for twenty two year cycles in Cosmic Rays, I know that Piers Corbyn did some analysis which he claimed showed no 11 year cycle but a clear 22 year cycle-something about “solar particles” being the driver. The trouble with his analysis is that it doesn’t allow for variable cycle length.

    Yeah, there are problems with the C14 and Be10 (which works like your description of C14 works)-for one thing, C14 is useless in the last century or so due to the “Suess effect” of fossil fuel burning adding C14 depleted CO2 to the air. But Be10 doesnt have ~that~ problem at least(but it has its own). Here is a graph of Be10 and Sunspot data:

    The trends of Cosmic Ray data depend on the energies-so Nuetron Chambers give different results than Be10 etc. Nir says that it is more relevant to look at high energies like this data:

    The reference for which (I did some digging) is:
    Ahluwalia, H. S.: 1997, ‘Galactic Cosmic Ray Intensity Variations at High Latitude sea Level Site
    1937–1994’, J. Geophys. Res. 102, 24,229–24,236.

    Possible connections between ocean circulation and solar activity are interesting, but there is a degrees of freedom porblem there, and if you extend it backwards, I doesn’t seem to keep working. Anyway, I don’t think most Solar physicists believe the Hoyt and Schatten TSI anymore-at least, that is the impression I have gotten.

    And the answer to your last question is yes, I find his (Nir’s) idea of spiral arm crossings (and hence GCRF variations) being the cause of the icehouse/hothouse cycles over the Phanerozoic quite plausible. 🙂

  8. carlwolk Says:

    Thanks, those are some very interesting links. I didn’t mean that there is not an eleven year signal, but it does seem to be dampened. If we decide that solar variation is the cause of modern warming, then it becomes apparent that the 11 year cycle becomes muddled and unclear (otherwise the temperature would be bouncing around significantly every 11 years. My point is that I wouldn’t expect the same thing from a change in low cloud cover; why doesn’t a 2% (1.2 W/m^2) change in low cloud cover create a clearer 11 year signal? This isn’t me not believing the theory, I just have some doubts.
    And about oceanic circulation. I just emailed a couple professors to ask for a paper they had written, and I’ll be posting on it very soon. I put more trust in changes in oceanic circulation than solar variation, though I have a hunch the two are connected.
    Also, I don’t know if you’ve discovered OMNIWeb yet, but if you havent: http://omniweb.gsfc.nasa.gov/form/dx1.html. If you graph IMF Magnitude from 1963331 to 2008125, with a 27 day average, you get a graph that clearly shows an increase in IMF peaks and troughs till cycle 23, which doesn’t want to end. (I’m rooting for it to keep going, that way we’ll probably have a weak solar cycle 24, and some projections have a cycle 25 that will be the weakest for centuries. If this global cooling/pause in global warming continues, the scare will quickly die.) Also, you can mess around with proton flux at various energy levels. Should be fun.
    Yet, IMF, 10Be, 14C, Neutron monitors, proton flux, etc don’t really matter if there has been no change in low cloud cover. And to the best of my knowledge (tell me if I’m wrong), we haven’t seen it.
    Also, have you been reading the Svalgaard thread on Climate Audit? If you have, what do you think of Erl Happ’s theory?

  9. Andrew Says:

    I don’t see why the effect of clouds would not be damped, as well-in fact, models predict (and they only include solar luminosity changes) a solar cycle amplitude of .03 degrees C, much smaller than what is observed. We haven’t seen a long term trend in Low Clouds becuase we don’t have long term data! Unfotunate, but true-especially since it is important to know how clouds behave if you want to really understand climate. I look forward to your post on ocean circulation changes, BTW. NIce link, thanks. Erl Happ’s theory seems, well, strange to me, and kind of counter to how I think climate works, so I have a hard time buying into it.

    There is an excellent presentation on solar effects here:
    http://acrim.com/Presentations/AGU%20Fall%202007/SanFrancisco-Scafetta.pdf
    I don’t agree with it 100%, but it has some informative slides. 🙂

  10. Glorified Says:

    Somehow i missed the point. Probably lost in translation 🙂 Anyway … nice blog to visit.

    cheers, Glorified

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