Skip to content

Atlantic Multidecadal Oscillation Is A Naturally Occurring Cycle

June 10, 2014

By Paul Homewood 


Further to recent posts on the Atlantic Multidecadal Oscillation, it is perhaps appropriate to show the full record, as shown by NOAA, which starts in 1850.





Clearly, the cycle is pretty regular, with peaks and troughs reoccurring about every 60 years.


NOAA also have this to say:


The AMO is an ongoing series of long-duration changes in the sea surface temperature of the North Atlantic Ocean, with cool and warm phases that may last for 20-40 years at a time and a difference of about 1°F between extremes. These changes are natural and have been occurring for at least the last 1,000 years.

Instruments have observed AMO cycles only for the last 150 years………… However, studies of paleoclimate proxies, such as tree rings and ice cores, have shown that oscillations similar to those observed instrumentally have been occurring for at least the last millennium. This is clearly longer than modern man has been affecting climate, so the AMO is probably a natural climate oscillation.

  1. June 10, 2014 2:40 pm

    Thanks, Paul. Yes, the AMO is a natural cycle, unaffected by the increase in atmospheric CO2 (at least until proven to be affected).
    And so are the rest of this planet’s cycles. I guess the question would be whether mankind is having an effect on these cycles, and the answer is easy and direct: We don’t know, because these cycles are long and we have been studying them since only recently.
    To design public policy based on such an assumption of man-made causality is criminally insane.

  2. John F. Hultquist permalink
    June 11, 2014 1:46 am

    The words used for some things have been poorly chosen (See greenhouse gas). In the current case the ill chosen terms are oscillation, cycle, and decadal (multi). Someone with a good grasp of the Queen’s English ought to offer better descriptors. Perhaps “recurring episodic phenomena” or REP could serve; giving AREP (A for Atlantic), and in the northern Pacific we would have NPREP, not PDO.
    “Naturally occurring” seems fitting.

    Why the NOAA author stuck in the word “probably” [last line] is a bit of a mystery. Andres’ comment is right on.

  3. tom0mason permalink
    June 11, 2014 4:41 am

    It is useful to see that from about 1975 onwards the temperature was rising. I wonder what the PDO was doing then?

  4. John F. Hultquist permalink
    June 11, 2014 9:55 pm

    PDO is not a measure of temperature.
    PDO is a numerical description of a pattern.
    Do not use PDO as a SST.

    • tom0mason permalink
      June 13, 2014 4:34 am

      Yes, well spotted, my slip.
      I’ll stand in the corner…

  5. Brian H permalink
    June 23, 2014 2:45 am

    A cycle is not itself a force, but a result of alternating dominance of forces competing with each other. Perhaps I’ve just missed the descriptions of them, and why they alternate. THAT would be useful …

Comments are closed.

%d bloggers like this: