Numerous scientific papers have reported the hiatus in global surface warming will end with the next El Niño event. But according to a new paper by Chen and Tung published today online in ScienceMag (link to paper follows), that’s not going to happen because the multidecadal variations in ocean heat sequestration at depth in the Atlantic and Southern Oceans will suppress surface warming for a decade or two more. Additionally, unlike many other papers of its kind, Chen and Tung (2014) indicate a lessening in ocean heat sequestration to depth (the reverse of what we’re seeing now) was responsible for the accelerated warming during the latter part of the 20th Century.
Looking at Chen and Tung (2014) in a different light, they went looking for Trenberth’s missing heat, and, not surprisingly, they found it in the same ocean heat content reanalysis (ECMWF ORAS-4) used in Balmaseda et al. (2013), which Trenberth co-authored.
The paper is Chen and Tung (2014) Varying planetary heat sink led to global-warming slowdown and acceleration. The abstract reads (my boldface):
A vacillating global heat sink at intermediate ocean depths is associated with different climate regimes of surface warming under anthropogenic forcing: The latter part of the 20th century saw rapid global warming as more heat stayed near the surface. In the 21st century, surface warming slowed as more heat moved into deeper oceans. In situ and reanalyzed data are used to trace the pathways of ocean heat uptake. In addition to the shallow La Niña–like patterns in the Pacific that were the previous focus, we found that the slowdown is mainly caused by heat transported to deeper layers in the Atlantic and the Southern oceans, initiated by a recurrent salinity anomaly in the subpolar North Atlantic. Cooling periods associated with the latter deeper heat-sequestration mechanism historically lasted 20 to 35 years.
Basically, Chen and Tung (2014) are saying that the vast majority of the human-induced global warming signal can be found in the ocean temperature and salinity data (and reanalysis) for the oceans to depths of 1500 meters. (There’s nothing new about that.) They are also clarifying that naturally occurring variations (that last for multiple decades) in where that ocean heat is sequestered (shallow or deeper layers of the oceans) impacts the rate of global warming at the surface. (There’s nothing new there, either.) During the “latter part of the 20th century” there was “rapid global warming as more heat stayed near the surface” and “[i]n the 21st century, surface warming slowed as more heat moved into deeper oceans.” While this proposal is not new, Chen and Tung (2014) are arguing against El Niño and La Niña as the primary cause and saying the variations in sequestration are occurring in the Atlantic and Southern Oceans…the result, primarily, of Atlantic meridional overturning circulation, with which the Atlantic Multidecadal Oscillation (AMO) is associated. The last little tidbit of value is the time periods of similar past cooling periods, 20 to 35 years, and that’s important because the current hiatus has not lasted that long yet.
Unfortunately, the Southern Ocean is one of the key regions in Chen and Tung (2014). There is so little long-term subsurface temperature and salinity data that far south that any reanalysis of the Southern Ocean before the ARGO floats were deployed (around 2003) has to be viewed as fantasy.
DATA AND REANALYSIS
Chen and Tung (2014) relied on the JMA ocean heat content data (Ishii and Kimoto) along with the COBE sea surface temperature data and on the ORAS-4 Reanalysis from ECMWF. As you’ll recall, a reanalysis is the output of a computer model that uses data as one of its inputs, so it’s not data. We discussed the curious behavior of the ECMWF reanalysis in the post Trenberth Still Searching for Missing Heat. The ECMWF ORAS-4 is forced by volcanic aerosols and ENSO to give it features that do not exist in data. Also see Willis Eschenbach’s post Why Reanalysis Data Isn’t…
Would the results of Chen and Tung (2014) be different if they had used another reanalysis of subsurface temperatures and salinity?
CHEN AND TUNG COMMENT ON OTHER PROPOSED REASONS FOR HIATUS
Chen and Tung (2014) discussed a number of the proposed explanations for the slowdown in surface warming. To these, they stated (
Response to solar cycle changes was found to be small (40, 41). The aerosol cooling should have a signature in subsurface ocean (42), and yet it is not seen, perhaps suggesting that the proposed radiative effects may be too small. The second involves ocean heat sequestration: The present work follows the original proposal of Meehl et al. (5, 24) regarding global deep-ocean heat sequestration. However, our observational result does not support their Pacific-centric view. The duration of the cooling periods in the CCSM4 model they used is typically 10 years, with one rare 15-year hiatus in 375 years and none over 15 years. The current hiatus already lasted over 15 years using their definition of hiatus as periods with zero trend. Comparing that model with observation, we found that model’s Atlantic has too little variability with too high frequency (fig.S7 versus Fig. 6). This artifact appears to be attributable to a new overflow parameterization scheme in CCSM4 in the Denmark Strait and Faroe Bank Channel (31).
CHEN AND TUNG CONCLUSIONS
The fact that the global-mean temperature, along with that of every major ocean basin, has not increased for the past 15 years, as they should in the presence of continuing radiative forcing, requires a planetary sink for the excess heat. Although the tropical Pacific is the source of large interannual fluctuations caused by the exchange of heat in its shallow tropical layer (3), the current slowdown is in addition associated with larger decadal changes in the deeper layers of the Atlantic and the Southern oceans. The next El Niño, when it occurs in a year or so, may temporarily interrupt the hiatus, but, because the planetary heat sinks in the Atlantic and the Southern Oceans remain intact, the hiatus should continue on a decadal time scale. When the internal variability that is responsible for the current hiatus switches sign, as it inevitably will, another episode of accelerated global warming should ensue.
So according to Chen and Tung (2014), an El Niño will only cause a temporary surge in global warming but not impact the multidecadal hiatus. But data contradict them. We know that strong El Niño events are a primary cause of global surface warming. Sunlight-produced warm waters released from below the surface of the western tropical Pacific during strong El Niño events (like ones in 1986/87/88, and 1997/98 and 2009/10) are then distributed to adjoining ocean basins in the wakes of those El Niños, and those El Niño residuals cause blatantly obvious upward steps in the sea surface temperatures of the South Atlantic, Indian and West Pacific Oceans. For more information on how strong El Niños cause those upward shifts, see the illustrated essay The Manmade Global Warming Challenge (42mb pdf).
However, in some respects, the sea surface temperature data for the North Atlantic do agree with Chen and Tung (2014). That is, the surface of the North Atlantic had been warming at a much higher rate than the rest of the global oceans during the satellite era (about 3 times faster)…until about 11 years ago. Since January 2003, the surface of the North Atlantic has been cooling, while the warming has slowed drastically for rest of the global ocean surfaces. (See the graph here.) So the North Atlantic has suppressed global warming for the past 11 years.
And, of course, the sea surfaces of the Southern Ocean show cooling for the entire satellite era, with a big step down in 2006-08.
Last, according to Chen and Tung (2014), hiatus periods due to the sequestration of ocean heat to depth in the Atlantic and Southern Oceans can last 20 to 35 years. And they note the current hiatus period has already lasted 15 years. That indicates we’ve got another 5 to 20 years more to go with the current hiatus.
Over the past few years, we’ve seen more and more papers that admit natural variability contributed to the warming from the mid-1970s to the turn of the century and suppressed the warming in the 21st Century. When will the climate science community admit they’d tuned their models to a naturally occurring upswing in the warming of global surfaces from the mid-1970s to the turn of the Century, and as a result their projections of future global warming are way too high? (Answer: Probably not in my lifetime.)
Thanks Bob! Your efforts are much appreciated!
“So according to Chen and Tung (2014), an El Niño will only cause a temporary surge in global warming but not impact the multidecadal hiatus”.
But that is really what you say. El Nino releases heat and La Nina’s and even ENSO Neutral absorb heat. The net is no impact. I think that is what you have been saying.
Looks like they are also saying the AMO and PDO have not really flipped. But I need to read not just your write up but their full paper. Unfortunately my subscription to Science does not get me to their full article.
Thanks for posting the abstract and your analysis.
Sig Silber: “But that is really what you say. El Nino releases heat and La Nina’s and even ENSO Neutral absorb heat. The net is no impact.”
Apparently, that’s your interpretation, not mine. I’ve never said or implied that. You’re forgetting about the redistribution of the heat outside of the tropical Pacific in the wake of the strong El Ninos, which is why I linked this graph in the post:
And you’re forgetting the El Nino and La Nina events are not opposites. And you’re forgetting the El Nino events dominate some multidecadal periods and that La Nina events dominate others, causing multidecadal variations in global surface temperatures.
Great post! Btw one typo Chen and Tung (2014) discussed a number of the proposed explanations for the slowdown in surface warming. To these, they stated (my boldface):
I can’t see any bolding
tonythomas061, the boldface is (as shown in my Firefox browser):
the slowdown is mainly caused by heat transported to deeper layers in the Atlantic and the Southern oceans, initiated by a recurrent salinity anomaly in the subpolar North Atlantic. Cooling periods associated with the latter deeper heat-sequestration mechanism historically lasted 20 to 35 years.
Thanks, Bob. I keep learning here.
When will the climate science community admit they’d tuned their models to a naturally occurring upswing in the warming of global surfaces from the mid-1970s to the turn of the Century, and as a result their projections of future global warming are way too high?
It will take a (political) sea change.
Andres Valencia, the “my boldface” tonythomas061was discussing was when I introduced the second quote in the post. In response to tony’s comment, I crossed out the “my boldface” there.
BTW, thanks Tony.
I have not at all forgotten that the ratio of El NIno to La Nina Conditions varies and in fact I have calculated it and concluded that during what is called PDO – it is 2:1 La Nina Conditions over El Nino and I did that calculation just by sorting the ONI values. I got the opposite ratio when I did it for PDO +. I do not draw any other conclusions from this since if the PDO is a product of ENSO then the PDO index is a surrogate for ENSO and I could have gotten the same results following a procedure more in line with your way of thinking. So I do not think we have any argument there: it is a substitution of variables. Plus as far as I know you have not attempted to segment time into periods where El Nino is dominant and periods where La Nina is dominant and if you did you may reinvent the PDO which again has nothing to do with what causes what. Correlation and causality are not the same thing. I follow your lag argument.
Yes I may be misinterpreting your assessment of ENSO but you do show some graphics where the ENSO battery, as I call it, fails to discharge more energy than it had absorbed or alternatively discharges more than it had absorbed. But elsewhere you show graphics that seem to show that ocean heating has occurred mostly in oceans other than the Tropical Pacific. I could find that graphic if I felt like it and I think it is one of your more important graphics. It kind of argues against ENSO being a driver of warming but your escape theory is a valid counter argument. Unfortunately you have not quantified your escape theory. Without being able to do that it is not possible to test your theory.
The major problem however I have with your analysis is simply how do we explain 1750. How come the World was getting colder prior to 1750 and now is getting warmer? If I assume everything you say is correct (and I do believe that a lot of what you say is correct) I still can’t explain the turning point in 1750 or thereabouts. `
So that is where i am stuck. I am not sweating the small stuff. I just want to know what happened in or around 1750. Between 46 million years ago and 42 million years ago there were 10 to 20 rises and falls of seawater in the Permian Basin. So that can be explained by astronomy and geology. I have a pretty good slide of that. But 4 million years divided by 20 cycles is 200,000 years per cycle. Perhaps there were 40 rises and falls of seawater in the Permian Basin as unconformities make counting cycles difficult. We are still talking about slow processes.
So that is the challenge to explain why the Planet was cooling for a long time and now appears to be warming. If you are correct that oceans contribute to warming, they have been doing that for thousands of years. So again what happened in 1,750? Did warming accelerate or cooling decelerate and if so why?
To me that is the central question.
The less central question in my mind is resolved. The IPCC has blown it on internal variability and thus most likely has the GHG sensitivity estimates too high. I do not even think that is worth discussing since it is so obvious. .But having that part incorrect does not explain why things post 1750 appear to be different than things prior to 1750. That remains to be explained.
Without explaining that, one is nibbling around the edges. That may be very useful re dealing with alarmism. But to me it is unsatisfactory because I want to know the real answer not just where some others have gotten it wrong.
The Hiatus has shown pretty clearly that one can not ignore ocean cycles. But it does not address the 1750 issue as I expect that the oceans had similar impacts on temperature prior to 1750. I have not read your someone turned the heat on book. Perhaps you answer this question in that book.
It would be a major achievement to have answered that question.
Sig Silber says: “I have not at all forgotten that the ratio of El NIno to La Nina Conditions varies and in fact I have calculated it and concluded that during what is called PDO – it is 2:1 La Nina Conditions over El Nino and I did that calculation just by sorting the ONI values. I got the opposite ratio when I did it for PDO +.”
Assuming you’re looking at the ONI sea surface temperature anomalies (not simply events), I hope you used the old ONI, not the new, because the old ONI uses a fixed set of base years, while the new ONI uses sliding sets of base years.
Sig Silber says: “If you are correct that oceans contribute to warming, they have been doing that for thousands of years. So again what happened in 1,750? Did warming accelerate or cooling decelerate and if so why?”
Can’t answer your question because we don’t have observations-based data since 1750, and we only have realistic sea surface temperature data during the satellite era, which is why I focus on it.
Bob, keep up the good work. I find the idea of massive amounts of heat being transported deep into the oceans and stored and then re-emerging from the ocean years or decades later to be one that should be critically reviewed. It seems to me that water does tends to heterogeneous behaviors in a fairly rapid fashion even in massive quantities like oceans. Surface currents don’t circulate heat for years but months. Why would things be very different in the abyssal regions where the flow is surrounded on all sides by cold waters?
The BBCs view
“Global warming slowdown ‘could last another decade'”
Unfortunately I used the new ONI http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml but I doubt that I would have gotten different results with http://www.esrl.noaa.gov/psd/enso/mei/table.html I think everyone here agrees that no index is going to be able to describe the condition of an ocean so if one set of indices is better or worse than another it probably makes not difference which you use when looking for very gross characteristics. I do not think you disagree that the ratio of El Nino Conditions varies with the PDO and again that is not a statement about causality just statistical analysis. I agree that ENSO is real and that PDO is not but rather an amalgamation of a number of things that are real such as ENSO, the location and strength of the Aleutian Low and the Western Pacific Currents. As you say it is useful for prediction salmon fishing results and seems to be useful for weather prediction purposes also but may not be the ideal index for that purpose.
“Can’t answer your question because we don’t have observations-based data since 1750, and we only have realistic sea surface temperature data during the satellite era, which is why I focus on it.”
I am sure you realize that is a totally unacceptable answer. It may be honest. But nature abhors a vacuum. So if there is no other explanation for a change in direction in 1750 or thereabouts others will propose their own explanations. The GHG theory makes some sense. I am pretty sure you could reproduce it in a cloud chamber shame they have none operational in the U.S. as far as I know. I thought the Colorado State U one shut down.
To me debunking is an unsatisfactory way of arriving at the truth. Not saying it has no value but I prefer dueling hypotheses. Right now they have one and you do not. That is a weak position to defend.
Finding flaws in the IPCC models is like stealing candy from a baby. It is so easy.
Your position is also a bit problematical since it implies that if we suddenly stopped all anthrorpogenic activity that contributed to GHG entering the Atmosphere temperatures would not START TO DECLINE AND WE WOULD NOT RESUME THE PLUNGE INTO THE NEXT ICE AGE. I find that hard to believe. So call me a running out of hydrocarbons alarmist. I think in 200 years Global Cooling will be a big concern.
Sig Silber says: “I am sure you realize that is a totally unacceptable answer. It may be honest. But nature abhors a vacuum. So if there is no other explanation for a change in direction in 1750 or thereabouts others will propose their own explanations.”
There you are wrong. That is a totally acceptable answer. Without data, there is only conjecture. Feel free to fantasize (somewhere else) because without data that’s all you’re doing. And if you haven’t noticed I focus on the satellite era for two reasons: (1) that is the period with the most reliable data, and (2) that is the period the IPCC says the warming can only be explained by an increase in manmade greenhouse gases. I personally do not care about the temperature in 1880, or in 1850, or in 1800, or in 1750, or in 1500…. They are meaningless in a discussion of anthropogenic global warming, when the IPCC claims only greenhouse gases can explain the warming in the past 30 years.
Sig Silber says: “Your position is also a bit problematical since it implies that if we suddenly stopped all anthrorpogenic activity that contributed to GHG entering the Atmosphere temperatures would not START TO DECLINE AND WE WOULD NOT RESUME THE PLUNGE INTO THE NEXT ICE AGE. I find that hard to believe. So call me a running out of hydrocarbons alarmist. I think in 200 years Global Cooling will be a big concern.”
There is no problem with my position, because it is based on data, not conjecture.
And, by the way, that is the most preposterous comment anyone has posted here to date. Without manmade greenhouse gases we’ll magically drop into an ice age? Ridiculous. Obviously, you have not considered the heat capacity of the oceans.
If you’re going to continue along those lines, I will request that you take your comments elsewhere. You’re wasting your time, my time, and the time of anyone reading this thread.
I do not fault you for wanting to have something close to real data to work with. But in the absence of alternative hypotheses the HGH hypothesis is the one to beat. That is not a vote for that hypothesis but a simple recognition that you can’t beat something with nothing. Al you end up doing is being on defense.
You are incorrect to say “Feel free to fantasize (somewhere else)” because I have not really or at least not intentionally offered up my own hypotheses. Obviously all of these hypotheses take a lot of work to attempt to defend. I see what you do and I am not up to that. So please do not assume I am offering up my own hypothesis. That the earth was cooling until fairly recently is not my hypothesis but is clearly documented in the historical record. So I do not consider it a fantasy to wonder if we would have continued to get colder if not for GHG or some other explanation.
It is not unreasonable to desire to have an alternative hypothesis for Global Warming that includes a mechanism for both warming and cooling. Both have occurred during the history of this planet including fairly recently history so any hypothesis let along theory has to account for both.
If you ban me I will miss posting but I will understand. I will not change my opinion of you which is very favorable. I will conclude the obvious. Questions you can not answer make you nervous. All I can say is it is not shameful to have not figured out every aspect of our world. It is very complicated. You are doing your part. And I appreciate your work. And I will buy your book.
If you want to ban me for saying that fine. It is your Blog, I will still read it. .
But I do not believe it is an unreasonable expectation for a scientific theory let alone a hypothesis.
y comments elsewhere that is not
This is related to the BBC piece that MWhite posted. It seems to agree with a lot of what you have been saying but I realize that if things are not said exactly the way you prefer, you do not recognize it as something you have said. For sure you are more precise than most people…I get that. We have to learn to live with sub-perfection when it still advances knowledge.
You have published graphics that show which parts of the oceans have warmed. This article seems to identify the same oceans. I am not sure the author has described the Thermohaline Circulation correctly. I do not think the Atlantic is more saline due to more evaporation but rather due to less water able to absorb alkali river inflows. The Pacific has more water per unit of river inflow than the Atlantic. Relative rates of E – P are important. The Pacific may have more P per square mile than the Atlantic.
Sig Silber says: “But in the absence of alternative hypotheses the HGH hypothesis is the one to beat.”
What is the “HGH hypothesis”?
Sig Silber says: “You are incorrect to say ‘Feel free to fantasize (somewhere else)’ because I have not really or at least not intentionally offered up my own hypotheses… …That the earth was cooling until fairly recently is not my hypothesis but is clearly documented in the historical record.”
The historical global temperature record does not extend back to 1750, which is the date you presented in your earlier comment. Many researchers don’t bother with data before 1950 because of the uncertainties.
Sig Silber says: “http://www.sciencemag.org/content/345/6199/897 This is related to the BBC piece that MWhite posted.”
You appear to be disconnected from reality. The sciencemag link you provided is to the Chen and Tung (2014) paper, which is the topic of this post.
Sig Silber says: “I do not think the Atlantic is more saline due to more evaporation but rather due to less water able to absorb alkali river inflows.”
And once again, you have presented no data to support your hypothesis. In other words, you are once again presenting fantasy. Please take it elsewhere.
Hello, I am doing an EPQ about the extent of the effect of El Nino on anchoveta catch size. During the regime shifts (the warm or cold phases) proposed by Chavez, when does the ocean generally absorb heat. Is it in the warm phase or the cold phase?
I know El Ninos are responsible for the release of some of the absorbed heat back to the atmosphere, so does that mean in a warm phase (which is dominated by El Ninos) that heat is generally released?
I’m aware that what I’m asking you guys is a really simplified version of what actually happens but I am just trying to understand the basics so I can double check that what I think happens is actually correct.
Katie, according to two papers by Kevin Trenberth, the tropical Pacific acquires heat in the form of warm water during La Ninas. The warm water is created by decreases in cloud cover (more sunlight reaching the tropical Pacific) which result because of cooler-than-normal sea surface temperatures. An El Nino then releases that heat from the tropical Pacific.
When El Ninos dominate, more heat than normal is released by the tropical Pacific to the atmosphere than normal, and more warm water is distributed from the tropical Pacific to adjoining ocean basins.
You will notice from my question that I am a very casual observer of this topic but trying to apply some common sense to reality. One of the arguments that comes up repeatedly is melting ice caps raises ocean levels, causing coastal flooding. My simple brain is thinking, water expands when it freezes and it sits roughly 90% below the water surface when floating (my Titanic iceberg science). The ice should be largely accounted for in the water levels. Seasonal temps cause freezing and thawing in most areas of the world, so there is always runoff into the oceans, reserving land based ice to glaciers. Considering there is evidence that warming temperatures have not interrupted the 60 year major crop yield trend, how does coastal flooding come about if it hasn’t happened yet? If the ice caps melt the water expansion essentially contracts to make room for it? Thanks.
Hi Curt: The two primary components of sea level rise are thermal expansion (brought about by the warming of the oceans) and the mass contribution from melting glacier ice (water that was once stored as ice on land is continuing to make its way to the oceans). There is also ground water pumping. That water also makes its way to the oceans, and it can also “undermine” some coastal areas, causing coastlines to drop in those areas.
There are a number of studies that present the minuscule contribution of melting sea ice to sea level, but those contributions are dwarfed by thermal expansion and the mass contributions.
How does coastal flooding happen, you asked? The oceans have warmed (regardless of whether you believe the warming was caused by anthropogenic or natural factors), which made them expand. And Earth’s temperatures have been above the threshold of those needed to melt glaciers since the end of the last ice age. Bottom line: Sea levels are rising. And there’s nothing anyone can do about it until we start heading back toward the next ice age. Isn’t that a nice thought?
And I am curious about something you wrote. How does the “60 year major crop yield” factor into sea levels?
Thanks Bob. One less thing off of my control list. The crop yield reference is actually from another group that looked at yields over time relative to temperature change. From my perspective, we are still growing more grain in the U.S. per acre over time regardless of the climate change chaos.
Curt, “climate change chaos”? That’s a description of weather, which is chaotic, extended over a multidecadal period.