A Look at the Atlantic Multidecadal Oscillation (AMO) Index
Posted by The Diatribe Guy on December 23, 2008
Previously, I took a look at the Pacific Decadal Oscillation (PDO) Index and showed that after a fairly long period of persistence in an average state above zero, it has dipped back down into the negative. It has now been in the negative level enough that the 10-year smoothed chart is actually negative. This has coincided with generally flat to cooling global temperatures, and colder weather patterns in the United States over the last few years.
I also took a look at the ENSO index over timeand showed that, while the ENSO cycle is much shorter-term, it also has been in a persistently warm state since the late 70s. I was one of the first I am aware of to point out the very recent readings in the Index pointing to another La Nina (there is some debate as to whether or not it is a “true” La Nina, since the cooler PDO could be driving this measure down. That seems silly to me. If you’re going to start arguing about influences to the index, then you can’t stop at the PDO.) In any case, the ENSO index is also running into recent negatives, and the persistent warm state appears to have finally come to an end.
It is reasonable, then, to wonder why global temperatures haven’t plummetted. While it is true that, current non-warming trends go back to May 1997, according to UAH anomaly dataand that all temperature measures show a declining trend line since 2001 to one extent or another, we have not been in a freefall on a global basis.
Certain regions appear to be more impacted than otehrs to recent cooler temperatures. The United States and Canada have had a much cooler time of it than Russia, for example. In fact, I previously took a look at the temperature anomaly maps and questioned why Russia seems to show consistently higher anomaliesthan the rest of the globe. I’ve checked the NOAA maps pretty consistently over the last couple years, and I have seen a lot of blue in the United States and Canada, and Russia burns bright red. This appears to be the most significant driver in temperature anomalies not hitting bottom.
It would appear that the PDO and ENSO do not drive Russian anomalies. At least, anyway, not as significantly as they seem to drive our region.
And so I decided to take a closer look at the other Ocean Index data. I have downloaded a boatload of data, and will be getting to each one in time. But I started with the other index we seem to hear a lot about – the AMO index. I started here because from what I understand, this is a pretty key index to keep track of. It also has the longest data history. In full disclosure here, I have not yet taken the time to look at the history of how these temperatures are recorded. I don’t know if they are direct measurements or modeled or some combination of the two. So, I simply present the data as given.
Starting out with the Raw Data:
From there, we collapse the data into 5-year average smoothing, which helps show the persistence of the anomalies
One step further, 10-year smoothing shows that we have really been in a persistent warm AMO pattern and that the increase in the anomaly has risen with a significant slope:
Looking at the above charts, I think each one tells an interesting story. The raw data itself demonstrates a very apparent cycle even without the smoothing. In some ways, smoothing almost hides it. An interesting thing about this index is that the magnitude of the swings are not nearly as large as the PDO index. The scale on the PDO chart was from -4.0 to +4.0. The index on the AMO is a range of -0.60 to +0.80. This tighter band illustrates a little better the absolute cyclical nature of this index.
Simply eye-balling the first chart shows that we are probably at the 3/4 point or so of the current warming part of the cycle. the last cycle had its first crossing of the zero state in 1924 and its final crossing in 1970 before a period falling solely below zero for a few years. The current cycle had its first such crossing in 1980, and seems to have reached a peak. This is the most persistently warm period in the index, with 76 consecutive monthly readings above zero. So, this warm phase of the AMO very likely helps explain why Europe and Russia have not seen the same kind of downturns in temperature as other areas of the globe.
You can really see the persistence of this current warm phase in the 5 and 10 year smoothing. You can see by the charts here that the AMO started its upturn at the same time the PDO crossed into the warm territory.
And now, it would appear that the AMO has reached its peak and is likely about to head downward just as the PDO is crossing into the negative territory. This is the same scenario as 1950, when the AMO started heading south just after its peak and the PDO entered its cool phase. The similarities are quite apparent.
Earlier today I quoted Joe Bastardi in another post. I want to revisit that, from this blog entry of his.
While it has been “chilly” so far, what is about to come is the worst in many a winter, perhaps the sign that the warm AMO is reaching its maturity. The U.S winter has been much like those around 1950 which was the benchmark winter in the Pacific Northwest of the U.S. and was the warning shot that the warm cycle of the ’30s, ’40s and ’50s was starting its end game. It should be comforting to people worried that we are pushing our planet over the edge that things that happened before are happening again, though the discomfort caused by cold is a big problem.
He references 1950, and he references the maturity of the AMO. Clearly, he is already in tune with the AMO phases and, I suspect, the PDO phases. The concurring charts of today look very similar to 1950, and so I do not think his comparison is unfounded. And if the phases of these two indices last as long as previous cycles, then we have a rough 10-15 years ahead of us.
Another point of interest is with the similarity of today’s sunspot activity with the period of the 1950s. In my previous post, Fun Stats With Sunspots and How They Stack Up Against Recent History I made the following observations:
*2-month average = 0.8: The previous 2-month average was 0.5, but prior to that the last time we’ve had a 2-month average this low was the period ending June 1954.
*3-month average = 0.7: This is the lowest three-month average since the period ending October 1913.
*6-month average = 1.8: The lowest 6-month average since the period ending December 1913.
*12-month average = 3.2: The lowest 12-month average since the period ending March 1934.
*2-year average = 6.7: The lowest since the period ending April 1924.
*3-year average = 10.2: The lowest since the period ending July 1935.
*4-year average = 15.9: The lowest since the period ending December 1935.
*5-year average = 22.0: The lowest since the period ending July 1936.
*6-year average = 30.2: The lowest since the period ending February 1937.
No matter how you look at the sunspot activity, we simply have not seen inactivity like we are seeing today since at least 1954, and earlier according to other average measures. However, unlike the PDO and AMO shifts looking like they did in 1950, there is a difference in the solar activity. In 1950, the sun was ending a period of lower activity and longer cycles, and the next half-century gave us higher activity and shorter cycles.
This may have helped counter the impact of the PDO and AMO cold phases of the next 20-30 years. That solar activity continued throough the warm phases of the AMO and PDO. Unlike that period, it appears that we are entering a cold phase of the PDO and a downturn of the AMO just as we did in 1950, but we are doing it at the beginning of a less active sun. Of course, we don’t know if the sun will stay this way, but history seems to indicate that we can expect it. For more information on that, click on my “Landscheidt” category.
I don’t want to be glib about this. I’m not wringing my hands in fear, nor am I gleeful at the thought of cooling, even if it shows the folly of the global warming alarmism that I despise. And while I don’t pretend to know all the ins and outs of climatology, I can look at charts and data. Sometimes the simplest answer really is the best one. Look at the charts. They explain the warming since the 1970s. They explain the last 10 years being flat. They explain why we’ve cooled and Europe/Russia haven’t. They explain why they too will soon will be cooling. They explain why this will likely be more predominant cooling than 60 years ago.
Carbon Dioxide may have some small impact in all of this, but it simply does not effectively explain near as much as all these other elements do.