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)
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What’s maybe very interesting is that their appears to eliminate ENSO as the main cause of global cooling (just eyeballing the graph) but not global warming.
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.
“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.
____________________________________________________________
Nicely done until Xie et al. got to the cause-effect tripwire, and fell flat on their face…
Just a thought, but maybe, just maybe, it is the modulations in El Nino which drive global temperatures, not the other way around. Given our current level of knowledge, climate scientists should, at the very least, be keeping an open mind on this issue.
Flawed thinking, or a need to throw a bone to the global warming police to get their paper through the peer-review process?
So much for the instant attribution of bad weather to AGW.
And look at that Oscillation correlation? Whoa.
And historically we live in a time of very minor fluctuations. Makes the Warmists look like hysterics. No wonder some believe that AGW is totally contrived and a fraud.
Where’s the corresponding La Nina graph?
How do you distinguish from an El Nino that missed the region from a La Nina that turned out cold & dry?
Fred.
The idea that a tree responds to local precipitation, is much more logical than that a tree responds to warming somewhere else in the world!
However, the problems using Bristlecones as proxies are well-known, so this study should be taken with a few mines of salt!
I realize that “eye-balling” is not a good scientific practice, but this chart appears to suggest the trend (green line) in ENSO is roughly flat for the last two hundred years. Are my eyes fooling me?
Being that it was a La Nina year, it wasn’t all that dry for areas of the SW. That tree from the Great Basin Park experienced wetter conditions this year. CA, NV, and UT experienced very wet conditions this winter. AZ and NM were pretty dry though. I realize they are using corals too, but you still have to be careful, because other weather patterns do play in here in the SW US.
http://www.hprcc.unl.edu/maps/current/
Fred, no trolling, please. It would be helpful to understanding climate if the multiple factors influencing tree growth could be separated out. Anthony gives any research that abides by the long-standing methods of science and reasoning a fair shot to make it’s case. Hyperbole, extrapolation beyond the data, unwarranted speculation, unsupported assumptions, and data-fudging get the criticism they deserve.
Interesting study and it is from this apparently accurate from the information given. I don’t see any correlation with AGW and didn’t see where the authors did either. My global warming theory? I predict this continent, both north and south will within the next six years heat up to whatever temperature is generated by a nuclear explosion .
I’d like to go back 2000 years to see two full 1000 year solar ‘cycles’ i.e. Roman Warm Period, Dark Ages, Mediaeval Warm Period, Little Ice Age, Modern Warm Period.
The period covered shows 1000 to 1600 as a period of weaker El Ninos which was the period when the level of solar activity would have been declining from the peak of the Mediaeval Warm Period to the bottom of the Little Ice Age.
Then the period 1600 to date with increasing solar activity and stronger El Ninos.
So what we do have is weaker El Ninos for about 500 years whilst the level of solar activity was declining and stronger El Ninos for about 500 years whilst the level of solar activity was rising.
A comparison with the previous 1000 year span would be interesting but I suspect that the further back one goes the less reliable is the data hence possibly the El Nino strength of the Mediaeval Warm Period could be understated.
Anyway so far as it goes this data does show a persuasive correlation between solar activity levels (or rather the trend in such levels) and the strength of El Nino events.
That ties in nicely with my proposition that the level of solar activity alters the surface pressure distribution, global cloudiness and albedo and thus the amount of energy getting into the oceans to fuel El Nino.
Fred says:
May 7, 2011 at 10:18 am
No, you’re not “checking the logic”. You’re just being a jerk, trying to sound precious and smart, and failing badly.
If you thought about what you just said, you’d realize that a given proxy is very often valid for one thing (say precipitation, as in this case) and not be valid for something else (say, long term temperature trend).
Duh …
w.
If it’s cold, there’s a lot of snowmelt, good for the trees. But if it’s hot, there’s convective rain, good for the trees. How do you tell the difference?
I must confess to being surprised there was no correlation between the El Nino strength and both the Medieval Warm Period and the Little Ice Age.
As far as proxy studies go, this seems to be an improvement. It is not perfect; however, it has more of an empirical component. They are trying to tie ENSO phases to periods of warming and cooling and to tree ring growth. That is the right direction to go. If proxy studies are to be used at all then scientists must explain all of the changes in proxy behavior. 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. This contribution by Jinbao Li on the effects of moisture that are tied to ENSO is a step in the right direction. Also, notice that the hockey stick is gone. Notice that recent warming is not exceptional. Finally, keep in mind that the hardcore modelers around Schmidt do not recognize ENSO as a physical process at all but treat it as statistical noise. So, this article is quite a departure from Schmidtian Alarmism.
Werner Brozek said:
“I must confess to being surprised there was no correlation between the El Nino strength and both the Medieval Warm Period and the Little Ice Age.”
But there is.
The El Ninos were weak for over 500 years during the descent and have been stronger during the subsequent recovery.
And that correlates with solar activity levels too.
Anything is possible says:
May 7, 2011 at 10:34 am
Flawed thinking, or a need to throw a bone to the global warming police to get their paper through the peer-review process?
This is what really bugs me about climate science…always giving a nod to CAGW, or AGW, or just GW, never leaving it out of the narrative. As Willis points out, tree rings are great moisture proxys, and not so good as treemometers. The rings are a reflection of mass generated while nutrient uptake was optimal…more likely when moisture is optimal than temperature. A relationship to a EN wet desert is a good correlation…until that rather boneheaded nod occurs. It is really difficult to keep reading when GW or CC pops up.
Stephen Wilde says:
May 7, 2011 at 11:13 am
I’d like to go back 2000 years to see two full 1000 year solar ‘cycles’ i.e. Roman Warm Period, Dark Ages, Mediaeval Warm Period, Little Ice Age, Modern Warm Period.
http://www.ncdc.noaa.gov/paleo/newpdsi.html
select area 35/46/47/36/58 etc.
You can download the data from these sets too.
Hook that beaut to the solar cycles. Ready, get set, we’ve gone?
============
To believe in tree rings requires that you believe 1/10th of a degree makes a difference to a tree……
and that warmer air holds more moisture and makes it colder and snow more
And requires that you believe that one thousand trees got it wrong….
…but eight, and only eight of them, got it right
Long term, it appears the amplitude of El Nino is increasing, and it began WAAAAAY before CO2 started to rise. You could possibly conclude that CO2 has absolutely no bearing on ENSO….
rbateman says:
May 7, 2011 at 11:54 am
Thanks, that looks useful but it will take me a while to work out how to operate it.
In advance I suspect that it will show stronger El Nino events leading up to the MWP and weaker El Nino events leading up to the Dark Ages which would presumably accord with levels of solar activity at those times too.
Liebig’s Law is usually thought of as relating only to nutrients, but includes, or should include, other factors such as moisture, humidity (which is not quite the same thing), ultra violet light, carbon dioxide, etc. I am a lifelong fuchsia lover currently living in an area where only a very few fuchsia types will grow satisfactorily. Most fuchsias will cease growth when the temperature drops to 6C, and will re-activate when the temperature rises to 8C. Several species will grow wild from escapes but only on western coastlines. Their sunlight requirements differ widely. Generally they love high humidity and will take fairly high temperatures provided that their individual sunlight tolerance is not exceeded. I have satisfactorily grown some types in the tropics in full sun at much higher temperatures than we experience here on the Natal south coast. The debilitating factor here (I believe) is high summer nighttime temperatures, 20 – 28C, in conjunction with very high humidity. They will not take the two together at night. Most fuchsia growers could not tell you that because nobody else makes the attempt to grow a plant that is just not suited to the area.
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.
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.
Mustafa says: “I realize that ‘eye-balling’ is not a good scientific practice, but this chart appears to suggest the trend (green line) in ENSO is roughly flat for the last two hundred years. Are my eyes fooling me?”
Nope. Your eyes are just fine. The linear trends of the HADSST2- and HADISST-based NINO3.4 SST anomalies since 1900 are incredibly flat. Here’s a graph that runs through 2009:
http://i56.tinypic.com/2ag0u2u.jpg
However, smoothing the data with a 121-month filter (same filter that NOAA uses to illustrate the AMO) shows the multidecadal variations:
http://i43.tinypic.com/33agh3c.jpg