...

[StudentOfClimatology]

I did not say this '95% in 1-2 year'. Please quote. This is a lie.

I apologize if I misquoted you, not trying to distort.

 

It is not necessary for the oceans to come anywhere near equilibrium temperature in order for surface temperature to become near equilibrium temperature. It is only necessary for SSTs to warm the majority of the way to what they will reach at full equilibrium (which could take many centuries).

The upper ocean is literally a mixing bowl, with upwelling/downwelling constantly occuring via Kelvin Waves and propagating stress fields...SSTs will respond in equiilibrium with the mixing layer, which is estimated to be 50-100m in depth.

[nflwxman]

Interesting thoughts from Trenberth on the PDO.  He actually speculates this coming El Nino could kick us back to a +PDO phase in the coming years.  Most would have expected this to happen in the 2020s, but I suppose it has been a solid 17 years since the last flip.

 

[nflwxman]

The PDO is theorized to be a wind/circulation driven resonance of some sort, but it does not affect the planetary energy budget. So I'm not sure why skeptics obsess over it.

That said, I think Trenberth in is mistaken. The stronger El Niños are almost always followed by multi-year La Ninas, and none of the El Niños during the last -PDO phase had any long term effect on it. The 1997-98 event, which is the gold standard, was followed by the lowest PDO in 30 years.

Essentially, Trenberth has zero evidence to back up his position.

For the most part, I agree.  He does mention that there has clearly been a shift in the PDO in the last year and sea level has risen dramatically in the eastern tropical pacific (even prior to the development of the current subsurface warmth in that area).

[StudentOfClimatology]

Sorry, I accidentally deleted my last post.

I agree we're probably in for another jump in global temps, I just don't think the PDO is all that relevant.

[ORH_wxman]

The El Nino of 1957-1958 saw a pretty steep rise in the PDO values. 7 months exceeded +1.0 and 17 of 19 months overall were positive. This was in the midst of an otherwise -PDO decadal regime.

 

If you want to argue that the current -PDO decadal regime started in 1998-1999, then we also saw a 3 year spike in PDO values from 2003-2005.

 

Others place the true regime shift in 2007.

[tacoman25]

Interesting thoughts from Trenberth on the PDO.  He actually speculates this coming El Nino could kick us back to a +PDO phase in the coming years.  Most would have expected this to happen in the 2020s, but I suppose it has been a solid 17 years since the last flip.

 

 

 

Nah, there's plenty of evidence the real downturn into -PDO phase didn't occur until 2006-08. See relative ENSO/PDO correlation and the sharp downturn starting then.

[nflwxman]

Nah, there's plenty of evidence the real downturn into -PDO phase didn't occur until 2006-08. See relative ENSO/PDO correlation and the sharp downturn starting then.

It's arguable on both sides.  It's not nearly as black and white as you make it sound.

[tacoman25]

It's arguable on both sides.  It's not nearly as black and white as you make it sound.

 

It's only arguable if you ignore the relative ENSO/PDO correlation I noted.

[tacoman25]

PDO-related? I think so.

 

 

 

[bluewave]

The Pacific climate shift occurred in 98-99 and is well documented in this recent paper. 

Trade winds have been the strongest on record since then surpassing the older -PDO era

from the 40's into the 70's.

 

http://journals.ametsoc.org/doi/full/10.1175/JCLI-D-12-00626.1

 

The use of a coupled ocean–atmosphere–sea ice model to hindcast (i.e., historical forecast) recent climate variability is described and illustrated for the cases of the 1976/77 and 1998/99 climate shift events in the Pacific. The initialization is achieved by running the coupled model in partially coupled mode whereby global observed wind stress anomalies are used to drive the ocean/sea ice component of the coupled model while maintaining the thermodynamic coupling between the ocean/sea ice and atmosphere components. Here it is shown that hindcast experiments can successfully capture many features associated with the 1976/77 and 1998/99 climate shifts. For instance, hindcast experiments started from the beginning of 1976 can capture sea surface temperature (SST) warming in the central-eastern equatorial Pacific and the positive phase of the Pacific decadal oscillation (PDO) throughout the 9 years following the 1976/77 climate shift, including the deepening of the Aleutian low pressure system. Hindcast experiments started from the beginning of 1998 can also capture part of the anomalous conditions during the 4 years after the 1998/99 climate. The authors argue that the dynamical adjustment of heat content anomalies that are present in the initial conditions in the tropics is important for the successful hindcast of the two climate shifts.

 

[chubbs]

Difficult to identify a specific date for the recent switch to negative PDO values since it occurred as a series of step downs instead of the steady decline that marked the 1940s transition. The recent recovery in PDO values is more robust than 09/10 but not as large yet as those assocaited with major PDO transitions. 

[tacoman25]

The Pacific climate shift occurred in 98-99 and is well documented in this recent paper. 

Trade winds have been the strongest on record since then surpassing the older -PDO era

from the 40's into the 70's.

 

http://journals.ametsoc.org/doi/full/10.1175/JCLI-D-12-00626.1

 

The use of a coupled ocean–atmosphere–sea ice model to hindcast (i.e., historical forecast) recent climate variability is described and illustrated for the cases of the 1976/77 and 1998/99 climate shift events in the Pacific. The initialization is achieved by running the coupled model in partially coupled mode whereby global observed wind stress anomalies are used to drive the ocean/sea ice component of the coupled model while maintaining the thermodynamic coupling between the ocean/sea ice and atmosphere components. Here it is shown that hindcast experiments can successfully capture many features associated with the 1976/77 and 1998/99 climate shifts. For instance, hindcast experiments started from the beginning of 1976 can capture sea surface temperature (SST) warming in the central-eastern equatorial Pacific and the positive phase of the Pacific decadal oscillation (PDO) throughout the 9 years following the 1976/77 climate shift, including the deepening of the Aleutian low pressure system. Hindcast experiments started from the beginning of 1998 can also capture part of the anomalous conditions during the 4 years after the 1998/99 climate. The authors argue that the dynamical adjustment of heat content anomalies that are present in the initial conditions in the tropics is important for the successful hindcast of the two climate shifts.

 

TRW.png

 

The 1998-99 -ENSO period only appears to be a "climate shift" because it was such an abrupt turnaround from the massive 1997-98 El Nino. It was all ENSO. The 2002-2005 period shows that the +PDO phase was still dominant overall.

[tacoman25]

+PDO intervals within a greater -PDO regime are common like we saw during the late 50's into the early 60s.

 

But the prolonged -ENSO 1998-2000 period did not represent a -PDO regime. It was a strong -ENSO period within a +PDO regime overall...as 2002-2005 proved.

 

Again, look at the ENSO/PDO relationship and you can see the shift that occurred 2006-2008. PDO values relative to ENSO began really falling then.

[ORH_wxman]

I think its hard to prove where the "turning point" was...it doesn't have to be a sharp turning point like the 1940s flip was...it could easily just be described as a gradual step down with 2007 being the final step down into the -PDO regime. Not all regimes and regime changes are equal. The early 20th century -PDO regime was weaker than the mid-20th century regime.

 

 

 

 

Its really just a matter of semantics.

[ORH_wxman]

And the duration and strength in the more distant past has exhibited quite bit more variability than we have seen

in recent times at least according to proxy studies.

 

http://adsabs.harvard.edu/abs/2005GeoRL..3208703M

 

Hydrologically sensitive tree-ring chronologies from Pinus flexilis in California and Alberta were used to produce an AD 993-1996 reconstruction of the Pacific Decadal Oscillation (PDO) and to assess long-term variability in the PDO's strength and periodicity. The reconstruction indicates that a ~50 to 70 year periodicity in the PDO is typical for the past 200 years but, was only intermittently a strong mode of variability prior to that. Between AD 1600 and 1800 there is a general absence of significant variability within the 50 to 100 year frequency range. Significant variability within in the frequency range of 50 to 100 years reemerges between AD 1500 and 1300 and AD 1200 to 1000. A prolonged period of strongly negative PDO values between AD 993 and 1300 is contemporaneous with a severe medieval megadrought that is apparent in many proxy hydrologic records for the western United States and Canada.

 

 

Yes...the "semi-permanent" PDO type behavior has definitely been documented...not just in the study you posted, but I believe there are others as well which point to monsoon activity in Asia and precipitation variability in the PAC NW.

 

 

Its also not an easy metric to really measure because it is actually a measure of temperature difference in two regions of the North Pacific and if that spatial distribution drifts over time, then you can get different readings.

[JBG]

The 1998-99 -ENSO period only appears to be a "climate shift" because it was such an abrupt turnaround from the massive 1997-98 El Nino. It was all ENSO. The 2002-2005 period shows that the +PDO phase was still dominant overall.

I think its hard to prove where the "turning point" was...it doesn't have to be a sharp turning point like the 1940s flip was...it could easily just be described as a gradual step down with 2007 being the final step down into the -PDO regime. Not all regimes and regime changes are equal. The early 20th century -PDO regime was weaker than the mid-20th century regime.

Correct me if I'm wrong but the "step-downs" seems to have started with the end of 1982-3, when +PDO seemed to have peaked.

[ORH_wxman]

Correct me if I'm wrong but the "step-downs" seems to have started with the end of 1982-3, when +PDO seemed to have peaked.

 

 

The "peak" was actually during the 1986-1988 El Nino...but you can see on the graph above in the thread I posted earlier how the 1990s were well positive too until the 1998-1999 La Nina which followed the Super Nino.

 

The biggest point of debate is when the "true flip" happened...whether it was 2007 or 1998-1999...there's argument for both time periods. Though I'm not sure it matters that much in the grand scheme of things except as an academic point. PDO cycles are not all the same and not all transitions between + and - cycles are as abrupt as the 1940s flip. Even the cycle length can vary a bit....we may be in this -PDO decadal regime for another 30 years or it could flip out of it in 10-15 years.

[tacoman25]

I think its hard to prove where the "turning point" was...it doesn't have to be a sharp turning point like the 1940s flip was...it could easily just be described as a gradual step down with 2007 being the final step down into the -PDO regime. Not all regimes and regime changes are equal. The early 20th century -PDO regime was weaker than the mid-20th century regime.

 

 

 

 

Its really just a matter of semantics.

 

As that graph shows, we didn't see the flip to predominantly -PDO conditions rivaling the 1947-1976 period until the mid/late 2000s. 

 

Beyond that, the weather patterns nationally from 1998-2006 were very unlike the previous -PDO phase. 2007-present, they have been much more similar.

[ORH_wxman]

As that graph shows, we didn't see the flip to predominantly -PDO conditions rivaling the 1947-1976 period until the mid/late 2000s. 

 

Beyond that, the weather patterns nationally from 1998-2006 were very unlike the previous -PDO phase. 2007-present, they have been much more similar.

 

 

I agree with that...2007-onward has been much more similar to -PDO regimes in North America atmospheric conditions than the prior 8 years.

 

Of course, that isn't the only way to measure it...which is why you could argue that 1998-1999 was a turning point too. Using other metrics like trade wind behavior. But certainly closer to home in North America from an atmospheric standpoint, 2007 was a much sharper demarcation.

[JBG]

The "peak" was actually during the 1986-1988 El Nino...but you can see on the graph above in the thread I posted earlier how the 1990s were well positive too until the 1998-1999 La Nina which followed the Super Nino.

 

The biggest point of debate is when the "true flip" happened...whether it was 2007 or 1998-1999...there's argument for both time periods. Though I'm not sure it matters that much in the grand scheme of things except as an academic point. PDO cycles are not all the same and not all transitions between + and - cycles are as abrupt as the 1940s flip. Even the cycle length can vary a bit....we may be in this -PDO decadal regime for another 30 years or it could flip out of it in 10-15 years.

I lack the professional training of many here, but a casual review seems to show about a 30 year length of cycles, at least post-1917.  Thus the "flip" timing would appear to have some predictive, as opposed to historical interest. 

 

To me, the importance of this is to debunk hysteria about long-term climate change.  During the mid-1970's there were fears of an "Ice Age" and some idiotic proposals to pollute the Arctic ice with carbon black. This was near the end of the negative PDO cycle.  Now the fear is of "global warming," a fear which rose to fever (pun intended) levels from the end of the 1980's through the early part of this millennium. Making the case that people should relax and not worry is easier if one can point to somewhat predictable cycles.

 

The AMO and the drought cycle gets less attention but in the U.S. Northeast there were concerns in the mid-1960's of a long-term drought, as NYC had annual rainfalls often under 40". The driest of these years was 1965, with less than 27" of rain.  The early part of the millennium was downright soggy by comparison, with 30 year moving averages of about 50" and many 365 day periods over 60".  Time will tell when we dry out again, but that process already seems well underway.

 

Thus, figuring out the length of cycles is somewhat important.

[JBG]

I agree with that...2007-onward has been much more similar to -PDO regimes in North America atmospheric conditions than the prior 8 years.

 

Of course, that isn't the only way to measure it...which is why you could argue that 1998-1999 was a turning point too. Using other metrics like trade wind behavior. But certainly closer to home in North America from an atmospheric standpoint, 2007 was a much sharper demarcation.

I tend to agree. But one difference was that 1982-3's El Niño fade to La Niña was very gradual. Ditto the end of 1990-3 and 1994-5.  1998, 2007 and 2010 featured veritable plunges from El Niño to La Niña, quite similar to 1973's and, I believe, 1953's. While a few "non-plunge" years featured late August through early October heat waves (1983, 1991, 1993 and to a lesser extent 1989 come to mind) those late season heat waves were quite pervasive in years featuring a rapid transition from El Niño to La Niña. 1970, 1973, 2007 and 2007 are good examples. 1998 was really the only "rapid plunge" year that did not feature such heat waves. Perhaps that was due to the strength of the prior Niño.

[bluewave]

http://www.wiley.com/WileyCDA/PressRelease/pressReleaseId-110825.html?cid=RSS_PRESSROOM2_PRESS_RELEASE

 

May 19, 2014

Different Types of El Niño Have Different Effects on Global Temperature

The El Niño–Southern Oscillation is known to influence global surface temperatures, with El Niño conditions leading to warmer temperatures and La Niña conditions leading to colder temperatures. However, a new study in Geophysical Research Letters shows that some types of El Niño do not have this effect, a finding that could explain recent decade-scale slowdowns in global warming.

The authors examine three historical temperature data sets and classify past El Niño events as traditional or central Pacific. They find that global surface temperatures were anomalously warm during traditional El Niño events but not during the central Pacific El Niño events. They note that in the past few decades, the frequencies of the two types of El Niño events have changed, with the central Pacific type occurring more often than it had in the past, and suggest that this could explain recent decade-scale slowdowns in global warming.

 

http://onlinelibrary.wiley.com/doi/10.1002/2014GL059520/abstract

 

 

eywords:

• ENSO;
• Climate Variability;
• Sea Surface Temperature;
• Climate and Interannual Variability;
• Decadal Ocean Variability

Abstract

The El Niño–Southern Oscillation is known to influence surface temperatures worldwide. El Niño conditions are thought to lead to anomalously warm global average surface temperature, absent other forcings. Recent research has identified distinct possible types of El Niño events based on the location of peak sea surface temperature anomalies. Here we analyze the relationship between the type of El Niño event and the global surface average temperature anomaly, using three historical temperature data sets. Separating El Niño events into types reveals that the global average surface temperatures are anomalously warm during and after traditional eastern Pacific El Niño events, but not central Pacific or mixed events. Historical analysis indicated that slowdowns in the rate of global surface warming since the late 1800s may be related to decadal variability in the frequency of different types of El Niño events.

 

[ORH_wxman]

It sounds like from that paper that they are saying we fail to see the huge step up in global temps during Modoki El Ninos whereas the east-based Ninos provide bigger steps in temperature.

[tacoman25]

More evidence that the PDO phases aren't just about having more of Nino or Nina.

[chubbs]

May PDO all the way up to 1.8. In previous negative period from 40s through 70s max was 1.76 in 57/58 el nino. Sustained levels above 1.8 have only occurred in plus PDO regimes.

 

 

2014** 0.30 0.38 0.97 1.13 1.80

 

1957 -1.82 -0.68 0.03 -0.58 0.57 1.76 0.72 0.51 1.59 1.50 -0.32 -0.55

1958  0.25  0.62 0.25  1.06  1.28 1.33 0.89 1.06 0.29 0.01 -0.18 0.86

 

 

 

 

[JBG]

May PDO all the way up to 1.8. In previous negative period from 40s through 70s max was 1.76 in 57/58 el nino. Sustained levels above 1.8 have only occurred in plus PDO regimes.

 

 

2014** 0.30 0.38 0.97 1.13 1.80

 

1957 -1.82 -0.68 0.03 -0.58 0.57 1.76 0.72 0.51 1.59 1.50 -0.32 -0.55

1958  0.25  0.62 0.25  1.06  1.28 1.33 0.89 1.06 0.29 0.01 -0.18 0.86

Do you see the long-term PDO negative phase as being over?

[ORH_wxman]

'57-'58 shows you can get a pretty long stretch of solid positive PDO values within a longer term decadal -PDO regime.

 

If we go longer than about one year of solid positives, then it would be more unique. You have to consider though that not all + or - PDO regimes are equal....the middle 20th century was a very potent negative regime...much more so than the negative regime in the late 19th and early 20th century. The positive regime from roughly 1920-1945 was not as strong as the one from 1977-2007 (or 1998, if you prefer that as the cutoff).

 

We like to compare everything to the 1945-1976 and 1977-1998 periods...but there is some evidence that those were quite strong compared to the previous 100 years...so expecting the PDO to mimic those periods exactly is probably a bit unreasonable. Comparisons should be taken with that in mind.

[JBG]

We like to compare everything to the 1945-1976 and 1977-1998 periods...but there is some evidence that those were quite strong compared to the previous 100 years...so expecting the PDO to mimic those periods exactly is probably a bit unreasonable. Comparisons should be taken with that in mind.

Are you saying we could be getting back tot he days of blander PDO fluctuations?

[ORH_wxman]

Are you saying we could be getting back tot he days of blander PDO fluctuations?

 

I don't think we can rule it out...I'm not sure I'd go there quite yet given the behavior of the trade winds, but it will be interesting to monitor. We're only working on 5 months of +PDO...some of which was aided by the blocking last autumn/winter in that region (and then there was a self-sustaining feedback of sorts)...for all we know, we could plunge right back into the strongly negative values next year when the current developing El Nino wanes.

 

In short, its way too early and too little data to make many accurate guesses about the longer term prospects of the current decadal negative regime. But its important to keep in mind that the PDO does have a lot of variability in the decadal behavior itself.

[chubbs]

We will only know in hindsight if the negative regime is over already.  The historic record is too short to provide much guidance.