As you know, Anthony Watts (quite wisely) mostly uses guests to write freeby articles for his blog. He gets into too much trouble when he tries to write something all by himself. Anthony doesn't need to determine whether his guests write nonsense or not. His good friend Wondering Willis Eschenbach gave him an "out" writing: "So it is not Anthony’s job to determine whether or not the work of the guest authors will stand the harsh light of public exposure. That’s the job of the peer reviewers, who are you and I and everyone making defensible supported scientific comments. Even if Anthony had a year to analyze and dissect each piece, he couldn’t do that job..." Yes, even his close allies think Anthony's incapable of distinguishing pseudo-scientific waffle from science.
Today Anthony's posted another article by David Middleton. This time David is waffling on about the Pacific Decadal Oscillation (PDO). The PDO is measured by an index. As Kevin Trenberth explained it in a recent Perspective article in Science (my paras):
There is also strong decadal variability in the Pacific Ocean, part of which is the Pacific Decadal Oscillation (PDO) (see the figure, panel B). The PDO is closely related to the Interdecadal Pacific Oscillation (IPO) but has more of a Northern Hemisphere focus. Observations and models show that the PDO is a key player in the two recent hiatus periods (2).
Major changes in trade-winds, sea-level pressure, sea level, rainfall, and storm locations throughout the Pacific and Pacific-rim countries extend into the southern oceans and across the Arctic into the Atlantic (7–9). The wind changes alter ocean currents, ocean convection, and overturning, for example affecting the Atlantic Meridional Overturning Circulation (10). As a result, more heat is sequestered in the deep ocean during the negative phase of the PDO (1, 6, 9, 11, 12). GMST therefore increases during the positive phase of the PDO but stagnates during its negative phase (see the figure) (13).
Here is a chart of the PDO index with ENSO added. The columns are temperature anomalies from GISTemp, El Nino years are orange, La Nina years are blue and the PDO index (from JMA) is in the background - as always, click the chart to enlarge it:
|Figure 1 | Global mean surface temperature (GISTemp) with La Nina years (blue) and El Nino years (orange/tan) and the PDO index, with PDO phases marked. Data sources: GISS NASA (temperature), BoM (ENSO years), JMA (PDO index), Trenberth15 (PDO phases)|
The figure below is adapted from the one on Nate Mantua's website, and shows the typical patterns in the North Pacific for the two different phases of the PDO during the northern hemisphere winter.
|Figure 2 | Typical wintertime Sea Surface Temperature (colors), Sea Level Pressure (contours) and surface wind stress (arrows) anomaly patterns during warm and cool phases of PDO. Credit: Nate Mantua|
Below is an animation comparing the sea surface temperature on 16 January 2012, when the PDO index was negative, with it on 14 January 2016 when the PDO index is positive. (As an aside, it looks as if this January will be another hot month, going by sea surface temperatures.)
|Figure 3 | Sea surface temperatures comparing January 2012 with January 2015. Source: NOAA|
David Middleton is a signed on science denier. He'll deny anything and everything on a whim. One time he decided to dispute some science about lizards, triumphantly producing some that he claimed countered the science. Problem was he had the wrong lizards! And the odd thing was that he could have used the findings to argue that (some) animals can survive climate change. The paper was about how lizards had found a niche that enabled them to survive 20 million years of changing climates.
This time he's arguing with experts about the Pacific Decadal Oscillation. He provides scant evidence for his claims. Mostly what he does is copy and paste some bits and pieces from an article at Climate Central and prance about saying that they are wrong.
As Nick Stokes in the WUWT comments observed, once again David produces the wrong evidence to counter one of the things he claimed was wrong. He quoted from the Climate Central article and added a comment:
Cyclical changes in the Pacific Ocean have thrown earth’s surface into what may be an unprecedented warming spurt, following a global warming slowdown that lasted about 15 years.
“Unprecedented warming spurt”… When? Where?Then he put up a chart, not of surface temperatures but of the lower troposphere. Dimwit.
Here's the unprecedented warming spurt:
|Figure 4 | Global mean surface temperature anomaly and warming spurt. Data source: GISS NASA|
After making the mistake of thinking the lower troposphere chart was a chart of surface temperatures, David really swung into action, denier style. He quoted a bit more from the Climate Central article and added his own notions, writing:
A 2014 flip was detected in the sluggish and elusive ocean cycle known as the Pacific Decadal Oscillation, or PDO
Firstly, the Pacific Decadal Oscillation doesn’t drive anything; so it could not be “playing a role in record-breaking warmth.” The PDO, particularly its long-term behavior is a response to, not a cause of warming and cooling cycles (quasi-periodic fluctuations). The late 20th century warming phase was coincident with PDO phase reversals.
He might as well say that ENSO doesn't drive anything, that El Nino and La Nina are just responses not causes of warming and cooling cycles. I bet Bob Tisdale would love that.
It flipped from negative to positive in 1976-77 and then flipped back to negative in 1997-98. Is there any indication that it has flipped from its cool to its warm phase as it did in “The 1976-77 Climate Shift of the Pacific Ocean“? My short answer is, “No.”David offered no data except a dinky little chart (see further down). He didn't put up the chart that was in the Climate Central article:
|Figure 5 | Cold PDO phases have a blue background; warm phases are red. Credit: Essay by Kevin Trenburth, "Has there been a hiatus?," which was published in Science in August, as posted at Climate Central.|
Here is a chart just of the PDO index (annual average) to the end of 2015, using data from JMA:
|Figure 6 | PDO index with PDO phases marked. Data sources: JMA (PDO index), Trenberth15 (PDO phases)|
You can see why Dr Trenberth might speculate that there's been a phase shift. It's spurted way up above any year in the previous warm phase. David Middleton put up a dinky little chart that was so small it was illegible, and it clearly didn't have the 2015 surface temperature (compare with Figures 1 and 4 above).
|Figure 7 | David Middleton's "evidence" at WUWT - full size. Source: WUWT|
PDO (University of Washington JISAO) and HadCRUT4 (Hadley Centre). The current upswing in the PDO is more analogous to the mid-cycle 1957-58 El Niño than it is to the 1976-77 Climate Shift of the Pacific Ocean.I'm no expert and the scientists probably won't confirm a phase shift for a year or two yet. (It usually takes a while to see whether it is a real shift or a temporary blip). However David is quite convinced (that there's no flip) and says:
The long term signal of the PDO as indicated by the 10 year mean and band pass filter is clearly still cool. Large swings of short duration are not uncommon. The current upswing is very similar to the strong El Niño of 1957-58, which occurred in the middle of a PDO cool phase. While it is possible that the PDO has begun to flip, it will be several years before we will know if this is a genuine phase shift or just strong El NiñoThat's a joke, right? He wants to wait for a ten year average to see if there's been a phase shift. Well, that might confirm one well after the event, but it certainly doesn't mean there's not been a shift already. The ten year mean taken today would comprise mostly the cool phase, so it's not much use in this case. It's true that swings have happened within a period without a complete shift to the opposite phase. However to say that large swings are not uncommon is an exaggeration. The only time there was a large swing opposite to the phase was way back in 1933, and the "large" bit was only one year, not two. As for the time in the 1950's - that's probably fair comment, although the index didn't get as high as it has the past two years. What is true is that only time will tell whether this is an extended warm phase or a short term blip.
Remember how David said that this year is "more analogous to the mid-cycle 1957-58 El Niño than it is to the 1976-77 Climate Shift of the Pacific Ocean"? Let's check.
Look at the PDO index in values for 2014 and 2015 and see if they look like the values in the "mid-cycle 1957-58". Since Figure 7 is so scrunched up, look at the data in Figure 6 above it. They don't, do they. The highest yearly average in the 1950s was 1.03 in 1958. In 2014 it averaged 1.13 and last year, 2015 it average 1.57. It hasn't been negative now for 23 months, not since February 2014. It was also positive from May 1957 to June 1960 except for one month, but was above one for only fourteen of those months. By contrast, since February 2014, there have already been 17 months where the index has been above one, and four months where it was higher than two. (It didn't rise above two at all in the 1950s.) This year the average was higher than that of any year in the previous warm phase from 1976 to 1998.
Now that doesn't mean that the index will stay positive or that this really is a shift in phase. Although the index is based on sea surface temperature, the PDO itself is associated with much more than temperature. It's also about how the wind behaves, and pressure gradients etc. And there are likely various teleconnections beyond the north Pacific.
The pseudo-scientist from WUWT, David Middleton, is very adamant that the PDO hasn't shifted back to a warm phase, but he can't see the future any more than you or I can. The scientists themselves are not nearly as dogmatic. One of the world's leading experts on the subject, Kevin Trenberth was quoted in the Climate Central article, talking about the effect of the Pacific on global surface temperature:
“It seems to me quite likely that we have taken the next step up to a new level,” said Kevin Trenberth, a scientist with the National Center for Atmospheric Research.Gerard Meehl, another expert on the subject, was quoted as saying:
“Last time we went from a negative to a positive was in the mid-‘70s,” said Gerald Meehl, a National Center for Atmospheric Research scientist. “Then we had larger rates of global warming from the ‘70s to the late ‘90s, compared to the previous 30 years.”
“It’s not just an upward sloping line,” Meehl said. “Sometimes it’s steeper, sometimes it’s slower.”
While Professor Michael Mann, who has published on oceanic changes in recent years, was quoted pointing out that the changes in the Pacific are still the subject of much research and debate:
“There’s some debate about whether there is a low frequency oscillation — is there a distinct interdecadal oscillation?” said Penn State meteorology professor Michael Mann. “Or is what we call a low frequency oscillation just a change over time in the frequency and magnitude of individual El Niño and La Niña events?”
Regardless, “it seems pretty clear that we’ve transitioned from a time period where there was a prevalence for La Niña conditions,” Mann said. “Over the past several years we’ve been in the multi-year El Niño state, and it has culminated with an extremely large El Niño event.”
David Middleton obviously couldn't bring himself to say that he tended to agree with Michael Mann's speculation. That would be a step too far for a climate science denier.
Thing is, as the scientists have pointed out, if there is a shift to the warm phase of the PDO, or a shift to more El Ninos than La Ninas, then the global mean surface temperature would be likely to rise more quickly in the near term.
From the WUWT comments
Deniers are a funny bunch. Some of them have an allergic reaction to climate science. John Francis can't bear it that the last two years have been the hottest on record. He quits altogether when he sees mention of a real climate scientist.
January 14, 2016 at 2:53 pm
Whenever we see the word “unprecedented” we know a load of nonsense will be forthcoming. and then we see the dreaded name Trenberth, and stop reading altogether.
ferd berple picks up on David's claim that the PDO doesn't drive anything, and quoting David wrote::
January 14, 2016 at 12:08 pm
It just doesn’t drive any of them.
cause and effect are a slippery slope. is it short days and long nights that cause winter, or is it the height of the sun in the sky, or is it the tilt of the earth’s axis with respect to its orbit around the sun?
p.g.sharrow tries to sound knowledgeable and waffles something trite and essentially meaningless:
January 14, 2016 at 11:46 am
Any time line of less the 180 years just demonstrates cycles in weather. The PDO is seen in weather cycles of localized conditions. Oceanic circulations are somewhat random so always some randomness should be expected…pg
Jeff in Calgary gets right to the point, from a denier perspective, but the moment has past, the temperature has already surged:
January 14, 2016 at 11:57 am
The ‘pause’ is our greatest weapon. I sure home the PDO does not bring a warming spike.
I'm not convinced that rbabcock knows much about ENSO or the PDO:
January 14, 2016 at 12:05 pm
First Bob Tisdale tells us El Niño has peaked and now this .. oh my.
CC Reader puts a question to Denier Don Easterbrook, who made an appearance (he hasn't for some time)
January 14, 2016 at 12:43 pm
Your article in 2008 indicated that you predicted a 30 year cooling of the PDO. Does this prediction still stand?
[Link replaced with archived version]
Don Easterbrook is in deluded denial when he replies:
January 14, 2016 at 5:18 pm
Yes. I made this prediction in 2000, based on a continuing pattern of PDO 60-year cycles (~30 yrs warm, ~30 yrs cool). In 1977, the PDO flipped from cool (where it had been from ~1945 to 1977), to warm in a single year, and we had global warming from 1978 to 1998. In 1999, when the PDO flipped back to cool, I projected the long-term PDO pattern into the future and predicted ~25-30 years of global cooling. The global climate has followed the PDO for the past century and glaciers have advanced and retreated accordingly. But the pattern apparently goes back even farther (500 years)–I plotted the oxygen isotope ratios back to 1480 AD using the accelerator data of Stuiver and Grootes and found 40 such oscillations, averaging 27 years long.
So far, my prediction seems to be holding. The climate has cooled slightly over the past decade and we have had no warming for 18 years. Time will tell if the cycle continues for another couple of decades. All indications are that it will. We’re just entering a Grand Solar Minimum, which, in the past, has correlated very well with climate.
No, Don, the climate has warmed this past decade, it hasn't cooled. Fifteen of the hottest years ever recorded in the instrumental era have been since (and including) 2001. Last year and this are the two hottest years on record. And the PDO doesn't swing in a regular pattern. It's not been 30 years warm and 30 years cool ever as far as I know.
For another record, here is Denier Don's 2008 prediction together with what has happened so far. I couldn't line the charts up precisely, but it's easy to see that Don and reality are going in opposite directions. (You can see others from him here.) By the way, the brown curve is reality, in case you missed it :(
References and further reading
Trenberth, Kevin E. "Has there been a hiatus?", Science 14 August 2015: Vol. 349 no. 6249 pp. 691-692 DOI: 10.1126/science.aac9225 (sub's req'd, I think)
From the HotWhopper archives
- Global Warming and the Pacific: Kevin Trenberth's Perspective - with more references listed at the bottom of this article
- Ice age deferred stymies David Middleton at WUWT - January 2016
- How David Middleton mixes up his lizards at WUWT: hot vs cold climates, eggs vs live birth - July 2015