From the University of Hawai’i’s International Pacific Research Center at Mānoa, comes this proxy reconstruction that does some similar things the infamous hockey stick reconstruction, but doesn’t need to pull any statistical “tricks” to make the case. Our old friend the Bristlecone pine in the southwest USA is the test subject again. Like Mann et al, they combined the recent instrumental record of ENSO variation with the proxy reconstruction record, except they didn’t need to delete any data, nor cover up any curves that didn’t behave as they wished. “Mike’s nature trick” wasn’t needed.
Why? Well it has to do with the Bristlecone pine being a better proxy for precipitation than temperature, and as we know, El Niño gives some significant precipitation impacts to the desert southwest. I’ve covered the issue of “treemometers” here and here previously, and they are worth a read as a refresher for this new paper.
They write:
During El Niño, the unusually warm surface temperatures in the eastern Pacific lead to changes in the atmospheric circulation, causing unusually wetter winters in the US Southwest, and thus wider tree rings; unusually cold eastern Pacific temperatures during La Niña lead to drought and narrower rings.
Liebig’s Law in a nutshell. In a desert, water is the limiting factor for growth, temperature, not so much. So I’m inclined to trust this reconstruction a bit more than I’d trust Mann’s. The test will be when somebody asks for the data for replication purposes.
Tree Rings Tell a 1100-Year History of El Niño
El Niño and its partner La Niña, the warm and cold phases in the eastern half of the tropical Pacific, play havoc with climate worldwide. Predicting El Niño events more than several months ahead is now routine, but predicting how it will change in a warming world has been hampered by the short instrumental record. An international team of climate scientists has now shown that annually resolved tree-ring records from North America, particularly from the US Southwest, give a continuous representation of the intensity of El Niño events over the past 1100 years and can be used to improve El Niño prediction in climate models. The study, spearheaded by Jinbao Li, International Pacific Research Center, University of Hawai’i at Manoa, is published in the May 6 issue of Nature Climate Change.
Tree rings in the US Southwest, the team found, agree well with the 150-year instrumental sea surface temperature records in the tropical Pacific. During El Niño, the unusually warm surface temperatures in the eastern Pacific lead to changes in the atmospheric circulation, causing unusually wetter winters in the US Southwest, and thus wider tree rings; unusually cold eastern Pacific temperatures during La Niña lead to drought and narrower rings. The tree-ring records, furthermore, match well existing reconstructions of the El Niño-Southern Oscillation and correlate highly, for instance, with δ18O isotope concentrations of both living corals and corals that lived hundreds of years ago around Palmyra in the central Pacific.
“Our work revealed that the towering trees on the mountain slopes of the US Southwest and the colorful corals in the tropical Pacific both listen to the music of El Niño, which shows its signature in their yearly growth rings,” explains Li. “The coral records, however, are brief, whereas the tree-ring records from North America supply us with a continuous El Niño record reaching back 1100 years.”
The tree rings reveal that the intensity of El Niño has been highly variable, with decades of strong El Niño events and decades of little activity. The weakest El Niño activity happened during the Medieval Climate Anomaly in the 11th century, whereas the strongest activity has been since the 18th century.
These different periods of El Niño activity are related to long-term changes in Pacific climate. Cores taken from lake sediments in the Galapagos Islands, northern Yucatan, and the Pacific Northwest reveal that the eastern–central tropical Pacific climate swings between warm and cool phases, each lasting from 50 to 90 years. During warm phases, El Niño and La Niña events were more intense than usual. During cool phases, they deviated little from the long-term average as, for instance, during the Medieval Climate Anomaly when the eastern tropical Pacific was cool.
“Since El Niño causes climate extremes around the world, it is important to know how it will change with global warming,” says co-author Shang-Ping Xie. “Current models diverge in their projections of its future behavior, with some showing an increase in amplitude, some no change, and some even a decrease. Our tree-ring data offer key observational benchmarks for evaluating and perfecting climate models and their predictions of the El Niño-Southern Oscillation under global warming.”
This research was funded by the National Science Foundation, National Oceanic and Atmospheric Administration, Japan Agency for Marine-Earth Science and Technology, National Basic Research Program of China, and the National Natural Science Foundation of China.
Citation: Jinbao Li, Shang-Ping Xie, Edward R. Cook, Gang Huang, Rosanne D’Arrigo, Fei Liu, Jian Ma, and Xiao-Tong Zheng, 2011: Interdecadal modulation of El Niño amplitude during the past millennium. Nature Climate Change.
Source here (PDF)
Stephen Wilde says:
May 7, 2011 at 1:16 pm
In some of the data around the peak/valley of 900-1000 BP, one can see some dry and wet data points that swamp all current maximum/minimums.
I saved data from sets 34 & 35 (NW & NE Calif.) some years back. I’ll compare to see if any of the ‘data’ has been monkeyed with.
Based on the list of funding sources, I would suspect that NOAA will eventually be including the data at their World Data Center for Paleoclimatology. I don’t see it there now:
http://www.ncdc.noaa.gov/paleo/recons.html#circulation
“Leif Svalgaard says:
May 7, 2011 at 1:26 pm
kim says:
May 7, 2011 at 12:21 pm
Hook that beaut to the solar cycles. Ready, get set, we’ve gone?
Except that that graph shows no correlation with anything solar.”
It shows low El Nino intensity whilst solar activity was declining from MWP to LIA and higher El Nino intensity whilst solar activity was increasing from LIA to date.
You are right that TSI cannot be the explanation but atmospheric chemistry in response to solar variations could well be.
River sediment from the south west rivers such as the Sacramento River should then show some correlation with tree ring data.
rbateman said:
“In some of the data around the peak/valley of 900-1000 BP, one can see some dry and wet data points that swamp all current maximum/minimums.”
Thanks, that is just what I would have expected if the MWP peak were higher than the recent warming peak.
If the jets were well poleward (more than in the late 20th century) then California could well have spent periods of time under the subtropical high pressure cells and other periods of time under the tropical cyclone paths which would have shifted poleward too.
If the jets were well equatorward such as during the LIA I would expect to see California instead dividing its time between the sub tropical high pressure cells and the mid latitude jets.
California could be a neat bellweather showing two distinct types of climate regimes at the extremes of global warming and cooling.
With global warming California becomes more tropical. With global cooling California becomes more temperate.
Stephen Wilde says:
May 7, 2011 at 1:57 pm
It shows low El Nino intensity whilst solar activity was declining from MWP to LIA and higher El Nino intensity whilst solar activity was increasing from LIA to date.
Except none of this is true. Solar activity was high around 1400, 1600 and 1780. E.g. slide 20 of http://www.leif.org/research/Does%20The%20Sun%20Vary%20Enough.pdf
And where is the solar cycle in Bob’s graph: http://i43.tinypic.com/33agh3c.jpg
Bob Tisdale says:
May 7, 2011 at 1:40 pm
Hello Bob,
The multidecadal variations show a heavy dominance of El Nino over La Nina during the period 1900 to 2009.
However the SST anomalies are flat.
Thus I assume that averaged from 1900 to 2009 the size of the excess of El Nino over La Nina remained constant through the period.
Would that be an accurate interpretation?
recall that there are two issue with BCP.
1. how much of the signal was temp versus precip?
2. signal bias due to mechanical issues (strip bark)
BCP should be avoided, unless those issues are addressed or resolved. Start by updating the proxies.
Latitude:
“And requires that you believe that one thousand trees got it wrong….
…but eight, and only eight of them, got it right”
There are two types of tree “complacent” and non complacent. Complacent trees have rings that dont vary a lot. they are not stressed, not at the limit. So its not a matter of some trees getting it right.
before you condemn prior to investigation, do a bit of reading. the BEST critiques of a science are found Within the science.
http://web.utk.edu/~grissino/principles.htm
site selection is what you need to read
http://web.utk.edu/~grissino/principles.htm#5
Theo.
“By contrast, neither Briffa nor other members of The Team have explained the famous “hidden decline” and, apparently, they long ago abandoned research on it.”
That is false. they study of divergence is ACTIVE. see espers 2010 paper on the subject which directly addresses Briffa’s issue
kim.
“hooking” it to solar cycles. You need to suggest a mechanism. otherwise we will just end up with cycle mania.
Ken Harvey says:
May 7, 2011 at 1:26 pm
“My point is that although we may have “experts” in the field of tree ring interpretation, I am not sure that we have any devotees who have spent much of their adulthood spare time growing bristle cone pines. If one has no intimate knowledge of the behavior of a plant in varying environments the ability to interpret must be considerably circumscribed.”
Now that is science. In fact, it is downright experimental! To the best of my knowledge, such thoughts have never occurred to a member of The Team or anyone doing proxy reconstructions of temperature. (Of course, I realize that Bristle Cone Pines do not lend themselves so easily to experiment, but a much more intimate knowledge of them is possible.)
for mosher:
I think I’ve never heard so loud
The quiet message in a cloud.
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I notice that they are now calling it the “Medieval Climate Anomaly” rather than “warm peroid”, we certainly do not want to associate the word ‘warm” with any period of time other than the present, now do we? People might get ideas…
Second, it shows a general warming trend (in the eastern Pacific) that starts some 900 years ago, long before the invention of the SUV. Furthermore, it shows no spike upward at about 1950, as it would if CO2 were driving increasing warmth. Conclusion, CO2 is not resulting in increasing El Nino, the variations are natural. The question then is, exactly what IS driving it?
Third, there are quite regular up and downs, and eyballing it, we are due for a down. Will the warmists blame the cold on CO2 as well, and what will they do if it gets cold enough everyone starts to notice? Will they say “my bad” and drop the whole CO2 thing, or will they do anything they can to hang on to power? Just how far are they willing to go with that?
Li et al wrote: “The weakest El Niño activity happened during the Medieval Climate Anomaly in the 11th century, whereas the strongest activity has been since the 18th century.”
Q#1: What is the origin of the phrase “Medieval Climate Anomaly”?
Q#2: Why use the non-standard phrase “Medieval Climate Anomaly” instead of the more well-known “Medieval Warming Period”?
Q#3: Why stop at year 1000?
Fred says:
“So you have had many posts pointing to the importance of ENSO for global mean temperatures, and now you are persuaded that bristlecone pines can give information about ENSO, but the idea that bristlecone pines might given information about global temperature is so outlandish that people looking into this are the worst scientists in the world? Just checking the logic here.”
Fred, the correlation of BCP with ENSO in the last few decades of the instrumental record appears to be very good in the graph above. The correlation of BCP with global temp in the last few decades of the instrumental record diverges badly, they don’t know why, they still used the series, and they covered up the divergence in their famous graph. Why don’t you check that logic?
Stephen Wilde says: “Thus I assume that averaged from 1900 to 2009 the size of the excess of El Nino over La Nina remained constant through the period.”
Nope. Consider the smoothed NINO3.4 SST data again:
http://i43.tinypic.com/33agh3c.jpg
Or consider the average NINO3.4 SST anomalies for two warming periods and the cooling period since 1910:
http://i56.tinypic.com/zxmsg8.jpg
And here are those period averages for NINO3.4 SST anomalies versus global SST anomalies:
http://i55.tinypic.com/33cwt4j.jpg
The last two graphs are from the post:
http://bobtisdale.wordpress.com/2010/11/17/multidecadal-changes-in-sea-surface-temperature/
steven mosher says:
May 7, 2011 at 2:32 pm
“hooking” it to solar cycles. You need to suggest a mechanism. otherwise we will just end up with cycle mania.
Plus that there really is no strong evidence for such a connection, rather the opposite:
http://wattsupwiththat.com/2011/03/19/the-minimal-solar-activity-in-2008%e2%80%932009-and-its-implications-for-long%e2%80%90term-climate-modeling/
Leif & Moshe.
There’s gotta be a pony in there somewhere.
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Oh, heck, gotta be a PDOny in there, unless it’s a LlAMO.
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Fred at 10.18 am the point was made in the introductory comments that growth and hence differences in tree rings, is more influenced by the availability of water rather than change in temperature. Consequently tree rings are a better proxy for ENSO related change rather than for temperature change.
kim says: “I think I’ve never heard so loud
The quiet message in a cloud.”
Bingo. It’s the inverse relationship between tropical Pacific cloud cover and Pacific trade wind strength during La Nina events that allow the sun to warm the waters that fuel the next El Nino. The periodic rise in central tropical Pacific Downward Shortwave Radiation during the La Nina events (as high as 45 watts/sq meter, if memory serves) can dwarf the variations caused by the solar cycle.
Legatus says: “Will they say ‘my bad’ and drop the whole CO2 thing, or will they do anything they can to hang on to power?”
They’ll simply blame it on the variatons in (warming vs cooling) aerosols.
Leif @ur momisugly 5:31
In your link, I find cba @ur momisugly 7:39 PM on 3/21/11 to be compelling. I think he suggests a way around the hypersensitivity.
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kim says:
May 7, 2011 at 5:59 pm
I find cba @ur momisugly 7:39 PM on 3/21/11 to be compelling. I think he suggests a way around the hypersensitivity.
I think his argument is circular: Changing the cloud cover would have a great effect on the climate, but a changing climate changes the cloud cover. The cosmic ray theory simply doesn’t work because the cosmic rays do not vary with the climate generally and BTW are themselves influenced by the climate [or rather the proxies for the cosmic rays].