Monday, October 29, 2007

Where is the European Warm Period in the Bristlecone Record?

Eli has always wondered how Malcolm Hughes avoided the storm associated with the Mann, Bradley and Hughes papers. Hughes, of course, was the dendrologist of the group, and head of the Arizona Laboratory of Tree-Ring Research.

A recent paper by Mathew Salzer and Malcolm Hughes in Quaternary Research 67 (2007) 57–68 provides additional information. The paper has modest, but interesting goals

Many years of low growth identified in a western USA regional chronology of upper forest border bristlecone pine (Pinus longaeva and Pinus aristata) over the last 5000 yr coincide with known large explosive volcanic eruptions and/or ice core signals of past eruptions. Over the last millennium the agreement between the tree-ring data and volcano/ice-core data is high: years of ring-width minima can be matched with known volcanic eruptions or ice-core volcanic signals in 86% of cases. In previous millennia, while there is substantial concurrence, the agreement decreases with increasing antiquity. Many of the bristlecone pine ring-width minima occurred at the same time as ring-width minima in high latitude trees from northwestern Siberia and/or northern Finland over the past 4000–5000 yr, suggesting climatically effective events of at least hemispheric scale. In contrast with the ice-core records, the agreement between widely separated tree-ring records does not decrease with increasing antiquity.
Tree ring widths are affected by temperature, precipitation and length of growing season (which may be correlated with the other two). High elevation trees are affected by large volcanic eruptions for several years. This allows Salzer and Hughes to differentiate between drought and the cooling brought about by eruptions. Looking at the tree ring index one can clearly see many large eruptions, the little ice age, but no European Warm Period, often called medieval.

44 comments:

Steve Bloom said...

Minus that cold spike around 1450, the LIA doesn't even look like much. Caldera?

The only really mysterious thing that I can see is the warm spike around 150 BCE.

Steve Bloom said...

1450 eruption => Kuwae.

Gareth said...

Foir the love of... loons?... can you get rid of that sound file, Eli? Makes me jump out of my skin every time I come here...

Cheers

Anonymous said...

Is it possible to provide a link to the article?

Alan Woods said...

I wonder why theres no modern warming (ie 1975+) signal? If you zoom into the graph you can see that it plateaus or possibly decreases in the last 20 years or so.

Anonymous said...

Simple enough to find the paper.

Best,

D

Anonymous said...

Alan, top para. of page 58 talks about recent contamination & effects on ring width.

Best,

D

Alan Woods said...

D,

that para seems rather speculative:
"The reduction in sensitivity may be associated with the atmospheric
contamination of the industrial era and/or the growth-promoting
effects of the historical increase in atmospheric CO2 content".

There doesn't appear to be growth promoting effects of CO2 after about 1975, and if the earlier rise is due to it, then I assume the early-mid 20thC T increase had no effect.

EliRabett said...

The loon sound is goon. Once is a joke 20 times is a pain:)

Anonymous said...

First, I would note that the paper refers to the correlation between bristlecone pine tree ring minima and volcanic eruptions.


Second, how much tree rings grow in a particular year really depends on which growth factor is limiting: length of season, temperature, water (even fire and possibly nutrients).

I'm certainly no expert, but I'd guess that drought has a very big effect on bristlecones in the southwestern US, so it is not only possible, but I would say likely that warmer temperatures might spur growth to a point as long as the rains come, but as soon as the rains stop, there goes the neighborhood.

As far as speculating about a 30 year period on that graph, I'd have to say that even when i enlarge it, I can barely see it.

Finally, the idea of CO2 fertilization assumes CO2 is the limiting factor with bristlecones. First, trees in general have had no great growth spurt in response to increasing CO2.

Second, having been to several stands in the Great basin, all I can say is "I doubt it."

Those bristlecones grow in some of the most inhospitable environments at the top of mountains. The soil is generally crap (very little organic matter), the growing season short and the only water they get is from the infrequent rains. In most cases, only a small part of the tree is alive. So I don't buy the "CO2 is limiting" story.

but then I'm not a bristlecone expert -- nor are the vast majority of the people speculating about such things (eg, at Climate Audit).

EliRabett said...

Among the things that I found most interesting was the enhanced response of the higher altitude trees vs. the lower altitude trees to both volcanoes and drought. I think the implication is that if you have a century long temperature increase/decrease, or drought you will find it in those trees first while one year effects will stand out.

EliRabett said...

Many of the series only go to ~1980 so I don't know if I would trust anything post then.

Hank Roberts said...

Does blogger let you eliminate 'anonymous' as an option while leaving people free to type in any name they like? Just a thought.

EliRabett said...

Not that Eli can see. Then again we are an old Rabett who welcomes new tricks.

Anonymous said...

but I would say likely that warmer temperatures might spur growth to a point as long as the rains come, but as soon as the rains stop, there goes the neighborhood.

Can't remember the paper now, but generally warmer means less snow hence less moisture (faster melt is bad) and summer rains are hit-and-miss; but such broad-brush assertions about rain aren't applicable in CA, as they experience a Meditteranean climate (and some want a cold-Med. climate to describe the high altitudes of the Whites, e.g.).

And with regard to the speculators at CA: The Google doesn't have a 'wisdom' button. Most of the Cheer Squad has never had a natural science course, judging from the inaneness of their remarks.

Best,

D

guthrie said...

Mann must have moseyed on over to the lab and mixed up the results in order to hide the evidence for a global medieval warm period.

Jimbo said...

Kuwae's 1450 eruption stands out, but the previous cold snap is something I've not seen before. Checking eruptions, it turns out there were three: Harrat Rahat in Saudi Arabia(?) in 1256, Hekla in 1300 and Katla in 1311 in Iceland.

Harrat Rahat has a Wikipedia entry; it was a 23km flow near Medina. I never knew there was volcanic activity in that sector - it looks way too far north to be related to the Rift valley and Red Sea volcanism (such as the little island that went off a couple of weeks ago). I tend to think that the somewhat close temporal proximity of Hekla and Katla in 1300 and 1311 would have had more influence, but it's still interesting

Anonymous said...

Since Salzer&Hughes are finding “higher than expected correlation between Finnish pine and North American bristlecone", how does that study relate to this one:

Climate patterns in Northern Fennoscandia during the Last Millennium (presented in the XVII INQUA Congress 2007).

The web site is here:
http://lustiag.pp.fi/

Anonymous said...

Full address of the last paper:

http://lustiag.pp.fi/holocene_trends1000_INQUA.pdf

Anonymous said...

Where is the European Warm Period in the Bristlecone Record?"

"Tree-ring data from southern Nevada indicated the region experienced drought during the Medieval [A.D. 950-1200] Warm period (Graybill and others, 1994)" -- From the "Climatic and Hydrologic History of Southern Nevada during the Late Quaternary" (R. M. Forester et al, USGS)

They considered a different area than the one in the White Mountains of CA and it is possible that the area in Nevada might have experienced a more pronounced drought than the one in California, which may bewhy it did not show up in the bristlecone record shown above.

but it is at least plausible that the growth increase that might normally accompany warmer temperatures *eg, due to longer growing season) might have been offset by reduced water availability, which would mean one would not see the effect in the rings.

MrPete said...

"Tree ring widths are affected by temperature, precipitation and length of growing season (which may be correlated with the other two). High elevation trees are affected by large volcanic eruptions for several years. This allows Salzer and Hughes to differentiate between drought and the cooling brought about by eruptions."

Quite a few suppositions in there. Recent papers (sorry, no time to do the linky thing at the moment) hae micromeasured annual ring growth and shown 90+ percent is in early spring as meltwater becomes available. And 90+ percent is all precipitation.

So of the three sources listed above, apparently precipitation dominates by far. Which leads to interesting questions like: would the MWP be seen in precip proxies? Would volcanic activity be seen in precip proxies?

Anonymous said...

So, the tree ring index does not show the recent warming, as pointed out by Alan. It does not show the MWP. It does not show the LIA, contrary to what Eli says, as pointed out by Steve B - LIA was around 1500-1700 not a sharp dip in 1450.
So what can we conclude from this study:
The tree ring index is not a proxy for temperature.

Elibatter

EliRabett said...

Look up latewood and earlywood. Spring growth is affected by when spring comes also, which is correlated with temperature. Precip is also correlated with temperature.

Anonymous said...

Mr pete, I found the reference below that talks about the role of precip in ring width.

But that may depend on where the tree is growing (ie, specifics of its microclimate)

It is particularly interesting that the conditions in the previous autumn are apparently also correlated with tree ring growth!



Tree rings and climate for the last 680 years in Wulan area of northeastern Qinghai-Tibetan Plateau
Journal Climatic Change


Published online: 9 January 2007

Abstract A 680-year ring-width chronology of Sabina przewalskii Kom. was developed for Wulan area of northeastern Qinghai-Tibetan Plateau, China. Response function and correlation analyses showed that spring precipitation (May–June) is the critical limiting factor for tree-ring growth, and temperature in prior November may also play a role in affecting tree-ring growth. Excessive spring precipitation occurred during AD 1380s–1390s, 1410s–1420s, 1520s–1560s and 1938 to present. Dry springs occurred during AD 1430s–1510s, 1640s–1730s and 1780s–1890s most of which generally coincided with cold intervals of the Little Ice Age (LIA) on the plateau, suggesting that the LIA climate on the northeastern Qinghai-Tibetan Plateau might be characterized by three episodes of dry spring and cold autumn. The relatively driest spring and probably coldest autumn occurred in AD 1710s–1720s, 1787–1797, 1815–1824, 1869–1879 and 1891–1895. The extreme drought in AD 1787–1797 might result from little monsoon precipitation due to the failure of Asian monsoon in this period. The tree-ring data produced in this study contribute to the spatial expansion of proxy climate records for the Qinghai-Tibetan Plateau.

-- T

Glen said...

There's a climateaudit response here.

Dano said...

I wish they'd hurry up and publish something discounting BCPs altogether.

That way, the ice fishermen in WI and MN can enjoy the later springs again and return to fishin'.

The pikas, too, can return back downhill in the newly cooler world.

Hurry, cheer squad! The critters want to move back down and south! Hurry!

Best,

D

Anonymous said...

Hey Dano, you still following the bugs as they move further north, or the critters as they move further west, or the butterflies as they move, oh, in any direction.

Old rabett uses some poor paper to make the faith warmer case, and it was only a matter of time before you came to add your directional delusions.

JohnS

Dano said...

Hey Dano,
[snip]
JohnS


I hope no one trumpets this as 'the best they can do'. Dano isn't so cruel as to paint them with the JohnS brush and the rest of us shouldn't be, either.

Do you act idiotic on purpose just to get abused. JohnS? Are you that twisted? I want no part of that game.

Best,

D

Anonymous said...

Judging by what he said about Hughes, McIntyre clearly has a bug up his ass, the poor dear.

"But what a typical climate science circus. Someone goes out and updates the critical Sheep Mountain data. It doesn’t show a Hockey Stick. Instead of using the updated version, Hughes uses the old version with a HS'

CA just got nominated for best blog, along with "Junk Science". How fitting.

Anonymous said...

Elibatter claims
"The tree ring index is not a proxy for temperature."

It's just that it is not a simple "temp goes up, tree rings get thinner" proxy as those like Elibatter like to assume for their strawman arguments.

One actually has to understand a little about trees and where they are located to figure out the story written in the rings.

Hughes falls in the category of someone who understands.

--Elibetter
(than Elibatter)

Anonymous said...

Well what about a quote from one of Hughes own students? "Unfortunately, the whole-bark and strip-bark chronologies from both sites do not correlate well with climate data from the surrounding valleys". "The strongest climate signal,..is related to the White Mountain instrumental precipitation data". Seems to agree with the paper cited by 'T' above.
And pointing out that the data doesnt fit the theory is not a strawman argument.

Elibatter

Anonymous said...

Still no comment to this paper, which also has a neat poster predicting global cooling...

Climate patterns in Northern Fennoscandia during the Last Millennium (presented in the XVII INQUA Congress 2007).

http://lustiag.pp.fi/holocene_trends1000_INQUA.pdf

- Onamat

Dano said...

OK, fine. Here is my comment on the paper:

The very last line of type says (human effect not included!)

I also note the graphs have modern temps warmer than the past, and I also note that the authors say Pinus sylvestris is a good indicator of JJ temps.

What's the big deal over this paper? Who is fetishizing over it?

Best,

D

Anonymous said...

Dano says,
"The very last line of type says (human effect not included!)"

What does that mean?

Also, Dano says: "I also note that the authors say Pinus sylvestris is a good indicator of JJ temps."

Not sure where they say that. I think they try to show coincident years where their composite high altitude chronology and 2 high latitude chronologies show very narrow rings (low growth). In an attempt to find eruption dates.

Is fetishizing a word?

Otto K.

Dano said...

It means, Otto, that they state their forecast doesn't include human influences on climate.

As to your Not sure where they say that , try reading the poster. The very next words at the top after 'Introduction'.

Smarter fetishizers please.

Best,

D

JoeDuck said...

Eli I'm new to these debates:

Are you suggesting that this is an indication there was not a European Warm Period or that it was not as prominent as some AGW skeptics claim or ?

What do you say about the hockey stick graphs at ClimateAudit that seem to challenge the idea that the recent warming is extraordinary.

Anonymous said...

Dano,

Sorry my mistake - I thought you were referring to the Salzer and Hughes paper, which is the subject of this post.

One thing I would suggest is that people realize Salzer and Hughes is not a temperature reconstruction, there is no transfer function, and they do not even consider post 1900 data in their analyses. As such, there is no reason for the authors to use updated Sheep Mtn. data for this work as demanded by McIntyre on CA.

Otto K.

Hans Erren said...

Dano, stop neologicizing.

Or is it verbingizing?

Anonymous said...

Otto K. said:
One thing I would suggest is that people realize Salzer and Hughes is not a temperature reconstruction, there is no transfer function, and they do not even consider post 1900 data in their analyses. As such, there is no reason for the authors to use updated Sheep Mtn. data for this work as demanded by McIntyre on CA.

I think they actually DO consider post 1900 data. As I read the report, it appears that data from 1900 to present were excluded only in the SEA analysis that is supposed to differentiate between volcano related ring minima and drought minima. They used events between 1600 and 1900 to generate the SEA “calibration” (if I can use that term) to which the entire data set was then compared. Table 2 in the report actually mentions frost ring signals in 1941 and 1965, and also indicates that there were no tree ring minima in the 20th century, other than the 2 frost ring signals.

Dan

Anonymous said...

Dano said...

"It means, Otto, that they state their forecast doesn't include human influences on climate.

"As to your Not sure where they say that , try reading the poster. The very next words at the top after 'Introduction'."

Agree that future forcasts must include human influences.

But the thread subject was "Where is the European Warm Period in the Bristlecone Record?"

It seems that the paper referenced does show a MWP (or "european" WP).

"anon:

Since Salzer&Hughes are finding higher than expected correlation between Finnish pine and North American bristlecone", then a MWP found in one should affect all similar trees.

And to take this one step further, a HS shape in the BCP should be found in the Finnish pines...

- Mickey

hanspeter said...

Elibetter vs. Elibatter: "One actually has to understand a little about trees and where they are located to figure out the story written in the rings."
How can you derive global temp data from local temp proxies, if local conditions prevail?

EliRabett said...

hanspeter, the point is to have enough locals (some of them with good brews). There is a very serious problem that there are not many long term proxys from the southern hemisphere, which is why MBH99 is titled "., Northern Hemisphere Temperatures During the Past Millennium: Inferences, Uncertainties, and Limitations".

Anonymous said...

MA chiming in again....

Did anyone ever stop to think that the trees alive are outliers, the ones that survived for some odd reason unrelated to their status as candidates as temperature proxies (assuming you can read the signal of temp through the noise of all the other factors)?

What about all those trees that died? Were they the abnormal ones, or are the ones that were "the fittest" the normal ones?

Odd little questions from the Mighty Anonymouse.

Anonymous said...

Oh, and you don't have to be an expert to speculate on the data that's being given to you. I don't know everything about ice, but I do know it melts and freezes at 32 F without having to ask anyone about it.


--MA