NASA’s Earth Observatory News announced the PDO has entered a cool phase, thought to enhance the effects of La Ninos and diminish those of El Nino. I snagged the larger NASA image of sea surface temperatures for April 14–21, 2008and highlighted the cool spot caused by the PDO and the cool spot caused by La Nina:
Josh Willis, JPL oceanographer and climate scientist, says of the PDO,
“These natural climate phenomena can sometimes hide global warming caused by human activities. Or they can have the opposite effect of accentuating it.â€
Yes. Indeed they can accentuate it or mask it. This might suggest that if the PDO is masking Global Warming now then it might have been accentuating during the 80s and 90s.
The empirically inclined might ask is: “How much masking or warming might exist in recent and future data?”
My answer is, “Beats me!”
I have not yet found anything suggesting the likely amplitude of peak-to-trough temperature variations associated with phase switches in the PDO. What I do know is PDO phases are thought to persist 20-30 years. What I don’t know is whether the the peak-to-trough effect thought to be 0.1K — as suggested for the solar cycle? Or 0.2K? Or a mega-whopping 0.5K? (That would be rather amazing! Needless to say, I’d also be surprised to hear such a number.)
Does it matter to the climate-blogging and/or voting public how large the magnitude might be? Well… I think it does.
I may be wrong, but I can’t help but believe that if climatologists believe the effect is large-ish, an estimate of that magnitude, and a comment on the current phase of the PDO, might have been welcomed by readers who downloaded “verifications” of IPCC projections against measured data. Possibly, readers of Rahmstorf 2007 or the IPCC AR4 would be curious to know whether the comparison between predictions and data occurred while the PDO was thought to amplify or mask global climate change; after all, both documents discussed comparison over partial cycles of the PDO. So, ideally, the amplitude might be discussed near those data comparisons.
On the other hand, if the effect of the PDO is (or was) thought small, then failing to mention that effect during verifications would be reasonable. (It follows that readers who assume climatologists make reasonable, non-tendentious choices when publishing their data comparison, might further assume that those authors must think the effect of the PDO is small.)
Still, as I have no idea what the effect might be, but I knew the PDO existed, I long ago suggested the PDO switch might be responsible for the recent flatness in GMST trends. The PDO phase switches are infrequenct, and so might trigger statistical outliers. (In fact, that’s the definition of an outlier: something that doesn’t happen often.)
So, in that regard, let us suppose the “warm” phase is associated with “warm” GMST anomalies and the cool phase is associated with “cool” ones. Then, what might one make of this?
Hhhhmm… maybe we’ve started “masking”, rather than “enhancing?”
Would it be cynical of me to suggest that we may read explicit estimates of the magnitude of the effect on GMST now that it might be masking rather than accentuating global warming? 🙂
The best part what where he said that PDO can Hide global warming or enhance it.
Think about that. I want such a toy in my understanding toybox.
Please bear in mind that shifts do not necessarily happens gradually, but may happen “abruptly”. Also that climate shifts (by whatever causal factor(s)) may lead to permanent or quasi-permanet changes in current patterns, thereby changing heat transportation into a new permanet or quasipermanent state.
Such an abrupt temperature increase could be observed in (almost the entire water column) in the North Sea in the 80ies. Apparently it has entered a new steady state (or quasi steady state). While the event have been linked to AGW, the situation is probably alao linked AO and AMD events.
Personally I check this:
(http://www.osdpd.noaa.gov/PSB/EPS/SST/data/anomnight.4.28.2008.gif)
page regularily.
It’s updated every third day or so. “Full Global” gives a nice overview. For the April 28 entry, also note the cold Indian Ocean and Antarcitc Circumpolar, dominated by below average SST.
Cassanders
In Cod we trust
Note from Lucia: I made the image show.
I am thinking about it.
But (as some may know) there are serious holes in my training.
Is this one of those Schroedinger cat-in-the-box things?
PDO Haiku
warm, cold, flip flop cold
a thirty year plus cycle
global warming, naught?
Ohh… I need to show my tulips and write a haiku for them. This years tulips are better than usual!
The 1998/2005 highs were right in line with those of 1934 and quite high as compared to 1976. The PDO effect then must be large. If the PDO’s warming enhancing effect can last 30 years, and their effect is large, then 30 years is not enough, by a long shot, to describe climate. Saying that “the globe warmed for the past 30 years” is meaningless. Remebering that the 1930s had similar temperatures as 1998, there was no anthropogenic global warming. The flucutaions in the past 100 years could easily have been from the PDO. Comparing those peaks with the troughs suggests that the PDO effect is large. Please remind me why the PDO, AMO and other oscillations were not included in the climate models. — John M Reynolds
John M Reynolds:
I assume you mean the AOGCM’s?
In principle, the PDO, AMO and other oscillations should arise naturally when AOGCM’s with sufficient resolutions, and realistic & accurate sugrid parameterizations for physical processes are used. However, one would not expect the models to consistently predict when a transition occurs.
So, even if models were perfect, when predicting or projecting something like GMST, climatalogists would only be able to describe its effect on the uncertainty in anticipating climate (or weather). They couldn’t tell you when the switches will happen.
Nevertheless, the fact that they can’t predict them doesn’t mean they can’t recognize which phase we are in when interpreting data and comparing data to IPCC projections since 1990 (but they generally don’t.)
From the JISAO site:
Lucia: For a number of years, I’ve been searching for a paper that identifies a coefficient for PDO to northern hemisphere surface temperature and/or global temperature, and I’ve come up with nada. But the way things work, if I say there isn’t one, someone might produce it. Here goes: “There isn’t one.”
Maybe explicit estimates of the effect on GMST will also be forthcoming for ENSO, since the frequency of La Ninas increases in the negative phase of the PDO, and forthcoming for the AMO, since it appears it may have already reached its positive peak–though with only two or three years of decreasing AMO, it’s tough to tell. The effects Trenberth produced for ENSO and that Knight produced for the AMO always seemed light to me. But I’m skeptical of everything.
I’d be happy with PDO or IPO data that hasn’t been standardized, but that’s not readily available, either, unless one wants to weed through gridded global SST data and extract it–which I don’t.
Regards
But we can find the magnitude of the PDO in the temperature data. Notice that visually, the slope of the temperature data from about 1910-1945 seems to match very closely with the temperature data from about 1975-present. And similarly, the slope from about 1880-1910 seems very close to the slope from 1945-1975. [In fact, if you take the slope from ~1910 to ~1943, you get a slope of ~1.6*/C, and if you take the slope from ~1975-~2004, you get a slope of ~1.8*/C. Similarly, if you take the slope from 1943 to 1975, you get a slope of 0.07*/C, while taking a visually similar period from 1880-1910, you get a slope of -.65*/C]. It’s interesting that when climatologists see a temperature drop from 1945-1975, they determine it is aerosol cooling, even though there is a very similar 30yr period with a similar downward trend – and it’s 30yrs earlier, no less. Similarly, they see a positive 30yr trend in the early part of the century – and call it natural – and then see another positive 30yr trend – 30yrs later – with a similar trend and call it global warming. But to me, when I start seeing the same alternating trends repeating at regular intervals, that’s a sin wave.
Unfortunately, there aren’t any standard techniques that I’m aware of for determining a best-fit sinusoid. So I wrote a simulation that attempts to find a best fit from the data using a genetic approach. After a couple hours it arrives at a bunch of answers, all pretty similar. The best fit was this sinusoid:
y = +4.00e-01*sin((x +4.29e+01) * 2pi/335.70) +1.03e-01*sin((x +6.09e+01) * 2pi/62.07)
Where y is the temp anomaly and x is the year (e.g. 1850.0 is 1/1/1850, etc.). The 336 year period is probably fictitious since there is only 150 years of data (although I constrained the magnitude to be 0.4 since that appears to match up with the magnitude of the medieval warming/little ice age from a plot on wikipedia).
A plot of that (red) against the actual temp data (blue) and the residuals (cyan) is here: Plot.png
As you can see, the magnitude of the 62yr sinusoid (which matches in frequency with your ~20-30yr PDO) is about 0.1 deg (0.2 deg peak-to-peak). And based on the PDO graph above, even the phases match pretty closely. The total sum of sinusoids above has local maxima/minima in 1948 and 1964 respectively, very close to what I would get by looking at your PDO graph (actually probably about 5 yrs delayed, which might make even more sense than 100% alignment).
But we can find the magnitude of the PDO in the temperature data. Notice that at least visually, the slope of the temperature data from about 1910-1945 seems to match very closely with the temperature data from about 1975-present. And similarly, the slope from about 1880-1910 seems very close to the slope from 1945-1975. [In fact, if you take the slope from ~1910 to ~1943, you get a slope of ~1.6*/C, and if you take the slope from ~1975-~2004, you get a slope of ~1.8*/C. Similarly, if you take the slope from 1943 to 1975, you get a slope of 0.07*/C, while taking a visually similar period from 1880-1910, you get a slope of -.65*/C]. It’s interesting that when climatologists see a temperature drop from 1945-1975, they determine it is aerosol cooling, even though there is a very similar 30yr period with a similar downward trend – and it’s 30yrs earlier, no less. Similarly, they see a positive 30yr trend in the early part of the century – and call it natural – and then see another positive 30yr trend – 30yrs later – with a similar trend and call it global warming. To me, when I start seeing the same alternating trends repeating at regular intervals, that’s a sin wave.
Unfortunately, there aren’t any standard techniques that I’m aware of for determining a best-fit sinusoid. So I wrote a simple genetic program that basically finds it by trial and error. After a few hours, it converges to some very similar sinusoids, the best of which is:
y = +4.00e-01*sin((x +4.29e+01) * 2pi/335.70) +1.03e-01*sin((x +6.09e+01) * 2pi/62.07)
where y is the temperature anomaly, x is the date in years (e.g. 1910.5 is June, 1910, etc.). The period of the sin is the part in the denominator (335.7 yrs, etc.). A plot of this sinusoid is here: http://picasaweb.google.com/jgrossman666/Random/photo#5194828807291716402 with the best fit (red), the temp data (blue) and the residual (cyan).
The 335 yr period is probably bogus because there are only 150yrs of data. But the 62 year period is probably fairly meaningful. And note that the period lines up pretty closely with the 20-30yr PDO. And the magnitude is roughly 0.1 deg (0.2 deg peak-to-peak). And even the phase seems about right from your graph of the PDO – the local maxima/minima are in 1948 and 1964 respectively, probably about 5 years behind the corresponding point in the PDO (which might make sense given heat stored in the oceans, etc.).
Using the definition of the PDO, we should be able to do a rough order of magnitude estimation of the effect PDO has on global (or NH) surface temperatures.
From here:
The Pacific Ocean spans about 90 degrees of longitude, about 1/4 of the Northern Hemisphere, and about 1/8 of the globe. So if temperature fluctuation are uniformily spatially distributed with the same magnitudes X, then NH temperature anomalies during the positive PDO phase would be about 25% higher than average, and global temperature anomalies would be about 12.5% higher than average.
This is obviously very rough, but the North Pacific is a large part of the globe. And the leading prinicple component is going to contribute a lot to the average temperature anomalies.
Bob Tisdale April 29th, 2008 at 1:37 pm
Sorry Bob, but I’m not the one that’s gonna burst your bubble. 😉
However, it concerns me that:
i) this hasn’t been done for something as well known as the PDO
ii) what *other* oscillations might exist. In timescales between 30 years ( ~ PDO ) and
100k years ( ~ milankovitch). Even if there’s only one such oscillation for every order of magnitude (and that seems conservative to me), we have no hope of disentangling them from weather “noise” with a mere ~150 years of good data (and that’s supposing it’s all good – there’s some contention about that too!)
Neil, there might be *other cycles*. For instance the ~1500 year Bond-Dansgaard-Oeschger event cycles: http://en.wikipedia.org/wiki/Dansgaard-Oeschger_event
Neil, there might be other cycles, e.g. the Bond-Dansgaard-Oeschger events every `1470 years, see e.g.
http://en.wikipedia.org/wiki/Dansgaard-Oeschger_event
You might take a look at the Dr. Landscheidt’s work for some hints at the PDO vs solar cycle:
Trends in Pacific Decadal Oscillation Subjected To Solar Forcing
In fact, all his work is quite interesting: Papers by Dr Theodor Landscheidt
Lucia: Since we’re discussing the Pacific and its effect on global climate, possibly you or one of your readers can explain why a running total of NINO3.4 data mimics global temperature anomaly. Refer to:
http://bobtisdale.blogspot.com/2008/04/is-there-cumulative-enso-climate.html
Bob,
“There isn’t one”
Sorry this isn’t the one either but its an interesting paper on the ‘Significance of the 1976 Pacific Climate Shift in the Climatology of Alaska’
http://climate.gi.alaska.edu/Research Projects/Hartmann and Wendler 2005.pdf
OTOH, you may have already come across it in your search.
You guys are working way above my head so all I can say is keep up the good work. But let me see if I have this right:
1) weak sunspot cycle 23
2) delayed sunspot cycle 24
3) PDO switch to cool
4) minimum half cycle of eccentricity
5) no global warming for 10 years with IPCC projection failure
6) increased antarctic ice
7) coming deep Gleissburg minimum
Bob, you know why no one has been able to burst your bubble right? It’s your fault. You don’t quote yourself! Putting in the quotes makes it seem like you are not sincere. You mucked it up! It won’t work now. 🙂
Lucia, looking at the graph, while there is a lot of chaotic noise, there does seem to be something of a sine wave there. As Lubos wrote:
In 1905, PDO switched to a warm phase.
In 1946, PDO switched to a cool phase.
In 1977, PDO switched to a warm phase.
In 1998, PDO showed a few cool years.
It is this constant back and forth that makes me think that it could be added to the climate models. Really, how well understood are any of the largest parameters anyway? Those got included. It just seems to me that they could have and should have added in the stronger oscillations like the PDO.
Josh, what is the residual (cyan) line from your graph, and what data set did you use for the dark blue temperature line? I had thought that the GISS data set had 1998 and 1934 to be very close to one another.
John M Reynolds
There seems to be a general view that the NASA announcement indicates the onset of another lengthy PDO cool phase. Considering that there was a short-lived cool phase after 1998, isn’t another short period a real possibility? Might not conclusions based on the current conditions, and the NASA announcement, be premature?
Duane: Sure. Conclusions would be premature. I think we are all speculating, and that’s never premature.
Speculations whether, both of the hair-brained and wild variety, and those grounded in the soundest of science, are necessary if we are to figure out which possible hypothesis best fits the data and/or figure out what theories are inconsistent with the data.
Lucia, my concern, ala Greenspan, is that we avoid “irrational exuberance”. I certainly was not intending to criticize your covering this on your blog, which has become a “must-read” for quite some time.
Also, since I have farm property in Northern Indiana, and have benefitted from several years of increased crop yields, I don’t exactly look forward to a long cool phase, should it occur. On the other hand, if the net result is more realism in the field of climate modeling and prediction, I suppose it would be positive in the long run.
Incidentally, I have a miniature dachsund who refuses to wear a jacket. It makes outdoor visits in the winter a problem for us both.
Duane, the “short-lived cool phase after 1998” was a strong La Nina and not half of a PDO or other oscillation. — John M Reynolds
Duane– Personally, I don’t expect cooling of any large magnitude. What I’m expecting is the PDO downward trend to mask underlying warming. If so, the temperatures may be very favorable for your crops, as the temperatures will neither warm nor cool precipitously for a period of time. Afterwards, you may be wishing you could move to ‘Da U.P.’
If you saw the close up of the temperature maps, you’d see Lake Michigan is supposedly anomalously warm. Let me tell you, I’m not noticing any anomalously warm weather in the Chicago ‘burbs!
chilly here too. My apt. building ran the heat last night although I personally think they just want any excuse they can to jack up my rent this summer. 🙂
that said it’s nice to have a real spring for a change. I remember far too many springs where it went from winter to blazing hot summer.
Lucia & others- is it my imagination or are we seeing an increase in peer reviewed papers hedging their bets &/or watering down the AGW predictions? I think the penny is starting to drop.
See for example this Nature article just published.
“Advancing decadal-scale climate prediction in the North Atlantic sectorâ€, Keenlyside et al, Nature, Vol. 453, 1 May 2008.
Abstract:
The climate of the North Atlantic region exhibits fluctuations on decadal timescales that have large societal consequences. Prominent examples include hurricane activity in the Atlantic1, and surface-temperature and rainfall variations over North America2, Europe3 and northern Africa4. Although these multidecadal variations are potentially predictable if the current state of the ocean is known5, 6, 7, the lack of subsurface ocean observations8 that constrain this state has been a limiting factor for realizing the full skill potential of such predictions9. Here we apply a simple approach—that uses only sea surface temperature (SST) observations—to partly overcome this difficulty and perform retrospective decadal predictions with a climate model. Skill is improved significantly relative to predictions made with incomplete knowledge of the ocean state10, particularly in the North Atlantic and tropical Pacific oceans. Thus these results point towards the possibility of routine decadal climate predictions. Using this method, and by considering both internal natural climate variations and projected future anthropogenic forcing, we make the following forecast: over the next decade, the current Atlantic meridional overturning circulation will weaken to its long-term mean; moreover, North Atlantic SST and European and North American surface temperatures will cool slightly, whereas tropical Pacific SST will remain almost unchanged. Our results suggest that global surface temperature may not increase over the next decade, as natural climate variations in the North Atlantic and tropical Pacific temporarily offset the projected anthropogenic warming.
See Andy Rivkin’s & Lubos Motl’s different takes on this article.
http://www.nytimes.com/2008/05/01/science/earth/01climate.html
http://motls.blogspot.com/2008/05/nature-amo-will-stop-warming-until-2020.html
I read the Revkin post yesterday. The Lubos one made me laugh; Lubos really gets upset, doesn’t he? 🙂
I think it is always the case, in all scientific areas, that people try to explain new data, particularly if it is in some ways surprising.
We’ve had a fairly long, flat spot in GMST during a period of time when, supposedly, we should have record breaking “underlying” warming.
So, I’m not too surprised to be seeing peer reviewed papers trickling out that are looking for ways to explain how and why we can get the current fairly long (8-10 year) flat spot in weather with no volcanic activity even if the rapid warming trend is expected. Yes, everyone who reads climate blogs knew about (hypothetical) long period oscillations, but clearly, the possible importance of 60 year long cycles used to be proclaimed by skeptics, and seemed to be given the silent treatment by bloggers who want to emphasize the reality of the enhanced greenhouse effect.
I’m planning to get the paper. It will be an interesting read! 🙂
Funny about the solar and the PDO thing. coinkydink?
Lucia
Its hard not to think that a shift in the PDO to a negative phase, as indicated by NASA, may not have a significant effect on global temperatures.
However perhaps the idea of amplifying/masking, as it moves through it’s cycles, oversimplifies what may actually be going on.
I assume you are aware of Roy Spencer’s ideas on “internal radiative forcing”. He has a forthcoming paper accepted by Journal of Climate, “Potential Biases in Feedback Diagnosis from Observational Data: A Simple Model Description.
He has also asked the editor of the Bulletin of the American Meteorological Society to consider publishing a paper “Evidence for Internal Radiative Forcing of Climate Change”. See also on Roger Pieke’s site, guest weblog by Roy Spencer, “Internal Radiative Forcing And the Allusion Of a Sensitive Climate system”. This is linked below and is an interesting read.
http://climatesci.org/2008/04/22/internal-radiative-forcing-and-the-illusion-of-a-sensitive-climate-system-by-roy-spencer/
He defines internal radiative forcing as “any change in the top-of-atmosphere radiative radiative budget resulting from an internally generated fluctuation in the ocean-atmosphere system that is not the direct result of feedback on temperature”. This is not a foreign concept in the literature, just not generally examined. The Nature article by Keenlyside et al for example refers to “external radiative forcing”(p 84, 4th paragraph).
From Roy Spencer’s web site linked below, in reference to the submission to the AMS above: –
“describes how mixing up of cause and effect when observing natural climate variability can lead to the mistaken conclusion that the climate system is more sensitive to greenhouse gas emissions than it really is. It also shows that a small change in cloud cover hypothesized to occur with the El Nino/La Nina and Pacific Decadal Oscillation modes of natural climate variability can explain most of the major features of global average temperature change in the last century, including 70% of the warming trend. While this does not prove that global warming is mostly natural, it provides a quantitative mechanism for the (minority) view that global warming is mostly a manifestation of natural internal climate variability. (This paper is sure to be controversial, and it will be interesting to see how difficult it will be to get published).”
http://www.weatherquestions.com/Roy-Spencer-on-global-warming.htm
While this is speculative, IMO a lot of papers on feedback also are, very much so. In a nutshell Roy Spencer is saying that failure to understand cause and effect has resulted in feedbacks been given a higher positive value than they really are, and they may actually be negative. As feedbacks make up approximately 2/3 of temperature sensitivity to 2 X CO2, they are very important.
So while it is perhaps not incorrect to talk about PDO amplifying/masking AGW, it may be more accurate to talk about AGW sloping the PDO cycle upwards with time. 🙂
A more complete theory would take all ocean cycles into account. Perhaps William Gray is correct.
2 amendments to my post above.
Roger Pieke’s site should read Roger Pielke’s (Senior)site.
The second last paragraph should read: –
“So while it is perhaps not incorrect to talk about PDO amplifying/masking AGW, it may be more accurate to talk about AGW sloping the global temperature cycle, due to PDO, upwards with time”. 🙂
Hi Lucia
During 2000-2007 the PDO went through two minor phases. During 2000-2004 the PDO was in a negative phase, in 2004-2007, a positive.
When I look at the weak amplitude of those phases, I see about the same swings in temperatures with nary an overall uptrend just using my eyeball filters. Contemporaneous were the positive AMO & NAO (forcings unknown to me) and a minor easing of solar radiation (I’ve read it’d be about -0.05 degrC/decade since 1990).
What I wish someone would do, and gosh knows why we’ve yet to see such a report, is take out the PDO noise masking/enhancing, cancel out the el Nino/la Nina & commensurate rebound effects, move the downtrend in solar radiation over to the CO2 column, deduct from CO2’s warming 30 percent for soot-driven warming worldwide (yes, it’s been finally found that tropospheric brown clouds carry a net heating effect despite surface dimming, contrary to conventional thinking), knock off an entire 19-20 percent of all AGW from a century of Arctic melting due to soot (yes, most of the boreal thaw is actually due to soot, dirty snow is warmer and melts faster) and the we’d have a good, solid number to pin on CO2. My WAG is that of the 0.65 degrC warming we’ve had, CO2 is accountable for about 45 percent of it to-date. Strangely, James Hansen has actually conceded a 45 percent figure in the past in discussion back in 2001. If CO2’s really responsible for only 0.30 degrC warming thus far, where’s the crisis?
BTW, all those numbers I can cite references to, esp. the tropospheric soot & Arctic AGW values. Those are biggies. I’ll check back to see if you want the references, I’ll go dig them up & e-mail them to you.
If the boreal environment is melting rapidly due to sootfall, and we risk a tundra-sourced methane-driven tipping point because of it, isn’t effort best spent on the most-immediate and readily-mitigated threat?
That is, do you do cost-risk analysis too?
I just returned from visiting Yellowstone and was struck by the devastation of the 1988 fires, which were preceeded by acute drought and record setting dry lightening. I began to wonder what solar activity occured leading up the 1988 fire storms. Solar cycle 22 started just a couple of years before that summer of drought and dry lightening. Check this out. Relative to other cycles, that solar cycle had 1) a very fast rise time – 2.8 years, 2) a very short cycle length – 9.7 years, 3) a high minimum sun spot number – 12.3, and 4) a high maximum sun spot number – 158.5
more:
“Cycle 22 certainly provided us with many highlights. Early in the cycle the smoothed sunspot number (determined by the number of sunspots visible on the sun and used as the traditional measure of the cycle) climbed rapidly; in fact more rapidly than for any previously recorded cycle. This caused many to predict that it would eclipse Cycle 19 (peak sunspot number of 201) as the highest cycle on record. This was not to be as the sunspot number ceased climbing in early 1989 and reached a maximum in July of that year. Whilst not of record amplitude, Cycle 22 still rated as 4th of the recorded cycles and continued the run of recent large solar cycles (Cycles 18, 19 and 21 were all exceptional!). A very notable feature of Cycle 22 was that it had the shortest rise from minimum to maximum of any recorded cycle.â€
Material Prepared by Richard Thompson. © Copyright IPS – Radio and Space Services.