Where are we in the PDO cycle?

Question

http://www.woodfortrees.org/plot/jisao-pdo/plot/jisao-pdo/to:1920/trend/plot/jisao-pdo/from:1920/to:1940/trend/plot/jisao-pdo/from:1940/to:1950/trend/plot/jisao-pdo/from:1950/to:1960/trend/plot/jisao-pdo/from:1960/to:1985/trend/plot/jisao-pdo/from:1985/trend

Answer 1

It’s difficult to say with any degree of certainty as a) we’re currently in the fickle transitional period, b) the PDO has short term fluctuations within longer term trends and c) we don’t know a great deal about the PDO and it’s behaviour.



There is some evidence to suggest that the PDO may have switched to the positive phase in the last few months, or be about to shortly However, it’s to early to say whether this is a short-term fluctuation or the start of a more pronounced positive phase.



The strength of the PDO is measured on the PDO Index (PDOI), which can roughly be translated as follows…



ANNUAL VALUES

>1.5 = very strong positive

1.0 to 1.5 = strong positive

0.5 to 1.0 = moderate positive

-0.5 to +0.5 = neutral

-1.0 to –0.5 = moderate negative

-1.5 to –1.0 = strong negative

<-1.5 = very strong negative



MONTHLY VALUES

>2.25 = very strong positive

1.5 to 2.25 = strong positive

0.75 to 1.5 = moderate positive

-0.75 to +0.75 = neutral

-1.5.0 to –0.75 = moderate negative

-2.25 to –1.5 = strong negative

<-2.25 = very strong negative



The PDOI for the year to date is 0.900, this is the highest it’s been for 11 years.



The most recent monthly PDOI is 0.82 (June 2014). Monthly values tend to jump up and down quite a lot. However, the trend in the months to May 2014 had been a general upward one and reached 1.80 in May. The recent monthly values are the highest for 9 years.



Based on what we’ve seen in recent months there is evidence to suggest the PDO has switched back to positive. However, in 1956 and 57 there was a similar pattern, namely a sharp rise that appeared to signal the end of the negative phase, this was short lived and the PDO remained neutral and moderately negative for the next 20 years. This was only 14 years after the previous peak so it would have been unusual to have such a quick turnaround.



Further evidence for a transition into the positive phase comes from the fact that each phase lasts for about 30 years, the highest recent annual peak values occurred in 1983 and 1987, thus sometime between 2013 and 2017 would seem likely for the next trough.



Here’s the graph of the PDOI since 1900 (blue line, first Y axis), also on the graph is the average global temperature (red line, second Y axis).



https://www.flickr.com/photos/trevorandclaire/14684239361/

The recent trend appears to show a move into the positive phase, but this is now less pronounced than it was a month ago:



https://www.flickr.com/photos/trevorandclaire/14477499527/

Here’s all 1373 monthly values up to May 2014 (you may need to download it to view it full size):



https://www.flickr.com/photos/trevorandclaire/14326867020/

What we can safely say is that the PDO will be switching to a positive phase and that it’s very likely to be in the next few years, if not already.



When the change does occur there is a lag in the response in global temps, the PDO needs to exit the neutral stage and remain in a positive state for some time before there’s a significant impact upon global temps. The warming signals within the first few years of a positive PDO will be small enough to get lost amongst the noise of other variables. As the signal increases, that’s when the effect on temps starts to take hold.



The most likely scenario is that temps will continue rising slowly in the next few years, in perhaps 10 years the effects of a positive PDO will become obvious, there will be a marked increase in temps for the following 20 or so years before a slow down and another levelling off.



- - - - - - - - -



UPDATE



The last time the PDOI trend went into the upswing it followed the pattern of the previous cycle almost exactly. If we project forward and assume that the current cycle will be a carbon copy of the previous one then the PDOI will reach its minimum value in 2022. This is shown by the green line on the graph below.



However, the current downswing is almost an exact replica of the last downswing except that it’s happening a bit faster and therefore the minimum is likely to be reached before 2022. If we apply a ‘best fit’ and superimpose the previous cycle onto the current one, the minimum will be reached in 2017; shown by the red line of the graph.



https://www.flickr.com/photos/trevorandclaire/14506316117/

Apologies if the graph is fuzzy, there seems to be a problem with Flickr at the moment, it’s also uploaded to here: http://postimg.org/image/9t7kpzg6j/



The first three graphs can also be found here:

http://postimg.org/image/o740g126l/

http://postimg.org/image/3p3139pwf/

http://postimg.org/image/5k01fyqir/full/

Answer 2

From the first graph in Trevor's answer, it looks like PDO does contribute strongly to variations in the rate of warming, but the temperature trend looks like a ramp added to the cyclical variation from PDO.

Answer 3

It's worthwhile remembering that the oscillation in the PDO refers to a seesaw between the Asiatic and North American sides of the North Pacific Ocean, with the negative or cool phase referring to the North American side. The net temperature change for the basin as a whole is zip. There are lots of reasons to expect this oscillation to affect weather in Asia vs North America\. there's no known causal connection (or even very good correlation) to global average temperature.

Answer 4

Never mind Trevor's long winded answers. There is a much simpler one. The PDO runs in cycles of roughly 30 years. It turned negative in 2000 so we are halfway through the cold cycle. Simple.



If you follow this back, you will find the warm cycle lasted from 1970 to 2000, the period which climate scientists based most of their climate models. They were expecting temperatures to continue rising and accelerate. They simply did not realize that stored heat in the Pacific was driving the temperature increase.



The period from 1940-1970 was a cool phase. Scientists are trying to blame the lack of observed warming on aerosols. But there is a much simpler explanation- PDO. The previous 30 years, 1910-1940 culminated in the some of the highest surface temperatures observed in the 20th century- driven by a warm PDO.



This didn't come from a blog, either. There are numerous papers in peer reviewed literature which talk about the PDO and its 30 year cycle. Here is one from Nature Climate Change.

Answer 5

Definitely D. For dumb ***.

Answer 6

We don't know. We may have a couple cycles, at most, to look at. In that limited data there is some evidence of multiple periodicities, but there could be others that we don't know about. We don't fully understand what drives it from what state to another. We are not particularly good at forecasting El Ninos, and we have even less experience forecasting PDO shifts.

Answer 7

We are in the neutral to negative phase.



http://jisao.washington.edu/pdo/img/pdo_latest.jpeg



Typically PDO events last for 20 to 30 years. What this means is that as the PDO changed modes in 1998 the positive phase will begin between 4 to 14 years from now. Does this mean that we'll have to wait until then to get a year warmer than 1998 in satellite data sets? Possibly. I'm not exactly sure the role the PDO plays in mid to lower tropospheric temperatures. It does have effects on the ENSO cycle which has an effect on these areas.



And Kano is wrong about the AMO index.



http://www.nefsc.noaa.gov/publications/crd/crd0911/images/f2-2.gif

Answer 8

About half way through the negative phase, we can expect more La Ninas and less El Ninos, the El Ninos we do get will be likely not be as strong as they would be in a positive phase.

Plus when the AMO turns negative (possibly soon) that should have a cooling effect as well, we wont see a combination of PDO and AMO in positive phase (that gave us the 1980-2000 warming) for some time.

Answer 9

I don't know, but I would say that 95% of the time when someone here posts a "Wood for Trees" graph without explanation or comment, that someone is an ignorant denier. Since you are neither ignorant nor a denier, and the question is a reasonable one, I would suggest (at least for future reference) asking it a different way or with a different link.