Digital Diatribes

A presentation of data on climate and other stuff

AMO Update – June 2009

Posted by The Diatribe Guy on June 9, 2009

The Antlantic Multidecadal Oscillation data has been released and the May index value is -0.014. That is the fifth consecutive negative value, and it’s the first time we’ve seen 5 consecutive negative months since the period ending October 1994. Previous to this negative stretch, there had been 77 consecutive positive months.

Similar to my look at the ENSO index, I have updated my best-fit sine wave against the AMO data. The chart is presented here:


Best-fit wave pattern against AMO data.

One nice thing about the AMO data as compared to the ENSO data is that it goes back to the mid 1800s. I cannot speak to the robustness of the index value, particularly for the older periods. I can only assume that it’s as good a measure as we have to work with.

A couple things can be noticed about this graph, especially in relation to the ENSO chart in the post referenced above. First of all, we are right now at the peak of the AMO wave. It last reached a trough in 1979, and has been increasing for the last 30 years. Since we are now at the peak, we will be descending down that wave now for the next 30 years, if the cycle is as presented. It should, however, remain in the warmer mode for the next 15 years of so, even though overall it is in a decline. Compare this to ENSO, where we just crossed the zero line.

It appears, then, that the ENSO (and PDO, as well) is offset almost exactly 90 degrees from the AMO. If true, this helps explain the contribution to warming over the last 30 years, and the stagnation of the last few years. 30 years ago, the AMO wave was at its trough, and the ENSO wave had crossed the zero line, moving upward. The next 15 years showed a situation in which all three waves were increasing. AMO from its trough up to the zero line, and ENSO/PDO from zero to its peak. Then, AMO increased while ENSO/PDO decreased, but both were above the zero line, so temperatures remained elevated, but the increase in temperature slowed and/or stagnated. Is it just coincidence? I suppose it could be. I consider that doubtful, however, because of the identification of waves in the HadCrut data that I presented.

Well, today, we are in the opposite siutuation as we were 30 years ago. The AMO is at a peak, and the ENSO/PDO index is at zero. It would seem, then, that we will experience significant cooling, along the same order as the warming of the 1980-2000 period over the next 20 years or so. Then, the period of time after that will likely be a stagnation of colder weather for 10-15 years, before we see the next warming cycle occur.

I’m sort of repeating what I did in this post. But it bears repeating. It seems fairly obvious to me, and it’s almost implausible to believe that such a relatively straighforward analysis that shows the Ocean cycles and how it affects the temperature cycles is not considered noteworthy when projecting forward temperature changes.

The other thing to note regarding the AMO chart above is that we seem to prematurely be getting some negative index values. I wouldn’t read much into that. Looking back at the chart, there are numerous times where negative readings – even consecutive ones – occur during the warmer side of the wave. In fact, the negative readings we see probably do indicate that we are in the warm wave yet, because the magnitude isn’t great, despite some persistence.

I may just be a layman and a data guy, but between this kind of analysis, a quiet sun and the analysis I’ve done as temperature relates to that, and the simple observation that we haven’t warmed in 12+ years, I can’t help but feel somewhat perturbed at the continuing warnings of global warming, and outright amazed at the audacity of predictions of multi-degree temperature increases by the end of the Century.

At this point, I would give odds on cooling until 2030 or so, regardless of what the fancy climate models say. It’s the only reasonable conclusion by looking at strict data. I suppose maybe the models say something that can’t be foound in the data. We’ll see.

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2 Responses to “AMO Update – June 2009”

  1. Page48 said

    Thanks for providing such a detailed explanation of the cycles. Hope you’re correct about their combined influence on global temps. Certainly seems logical. Time will tell, I suppose.

    Nature’s bringing out a new CO2/AGW correlation paper today or tomorrow. I look forward to seeing what all of you statisticians make of it.

  2. [...] (3) A look at the AMO data, demonstrating where we are in the current cycle, and where we’re h… [...]

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