Bishop Hill New tree ring paper
Jan 14, 2011 Climate: MWP There is an article in New Scientist today, describing a new paper in Science by Büntgen et al. This is a tree ring study using samples from France, Germany and Austria to recreate temperatures and precipitation for the last 2500 years. There is a hint of a lack of a Medieval Warm Period:
From AD 250 to 550, the climate flipped, from one decade to the next, between dry and cool, and warm and wet. "Such decadal changes seem to have the most impact" on civilisations, Büntgen says, because they harm agriculture but are not prolonged enough for people to adapt their behaviour.
The climatic turmoil coincided with political upheaval and waves of human migrations. By AD 500, the western Roman Empire had fallen.
In other notable periods, the relatively stable medieval society was characterised by more constant climatic conditions. But the Black Death coincided with a wet spell and the disease spreads faster in humid condition
Reader Comments (33)
there does seem to be a drive in promoting historical non-co2 warming climate change as crucial to anthropological history. right up to to being the final arbiter in the rise and fall of civilisations. there's some interesting facts in the aqrgument but get ready for academic exageration.
Drawing only from the "New Scientist" summary, one might ask why some trees were chosen to represent precipitation and a lesser number to reconstruct temperature. Can anyone who has the full article describe how trees are differentiated into precipitation trees and temperature trees?
Shame that Edward Gibbon had to spend 6 volumes to discuss the Rise and Fall of the Roman Empire when there is such a simple explanation.
But is it? One can ask many questions. Was the asserted preference for Chinese war in cold times because that was when armies could cross frozen rivers rather than fluid ones? Many questions of that type come to mind as extraneous variables.
I continue to be worried by the logical reduction of time and event resolution over longer and longer periods. It's obvoius that more sparse, older data will capture fewer anomalous events that can affect an average reconstruction.
What on earth have the Black Death, the fall of the Roman Empire and Medieval Society got to do with a study of tree ring proxies?
Here is the abstract of the paper in Science. Note the compulsory 'unprecedented' mantra and the blatant political activism in the last sentence.
@ Pete Hayes
Sounds like a quiz question.
Here's my favourite quiz question.
Q. Who is the odd one out - Nigel Farage of UKIP, Don Corleone of the Mafia, Osama bin Laden, and Kenneth Lay of Enron?
A. Nigel Farage. All the others support the consensus on climate change.
"Recent warming is unprecedented, but modern hydroclimatic variations may have at times been exceeded in magnitude and duration."
Eh? What? Unprecedented, but previously exceeded? I'm not sure why 'warming' is differentiated from 'hydroclimatic variation'; I guess the latter is a wider term, but this is getting Jesuitical in it's wriggling. I guess it's a case of having to read the whole paper because the abstract doesn't make sense. As for the political statement at the end, that more or less shouts 'I'm not a real scientist actually'.
The New Scientist article may be painting it's own view, as I'd be surprised if the original paper was claiming causality for the various political and social changes (rather than weak correlation) without a much beefier set of evidence.
what? People are still taking dendrochronology seriously?
:¬/
The climatic turmoil coincided with political upheaval and waves of human migrations. By AD 500, the western Roman Empire had fallen.
The same point is made in Singer and Avery's generally excellent "Unstoppable Global Warming" but suffers IMO from the same logical flaw. Not only did the eastern Roman Empire not fall for another 1000 years but the western half was supplanted by what are still often called "barbarian" civilisations.
AGW theory generally supposes - and, as we all know, discusses the notion at interminable length - that the less developed world is most at risk. If, therefore, it is surmised that the driving force for the collapse of Imperial Rome was primarily a changing climate and the notion is advanced to support AGW theory, it is necessary to explain why technically less developed cultures were in the event more robust.
The apparent paradox may explain why simplistic theories relying heavily on climatic factors are generally favoured by writers whose expertise lies outwith the discipline of history. Historians, rightly in my view, generally eschew them.
Geoff Sherington:
Shame that Edward Gibbon had to spend 6 volumes to discuss the Rise and Fall of the Roman Empire when there is such a simple explanation.
Quite. But he wasn't peer-reviewed so, arguably, he just sort of got away with it.
Aren't there problems in using Stone Pines in the Alps as a summer temperature proxy due to concerns over the impact over temperature thresholds, short term weather extremes and sensitivity to soil and airborne contanimants on the tree's growth.
Again, aren't there problems in using the European larch as a summer temperature proxy due to research that showed that this tree's growth is directly related to summer precipitation and higher than normal winter temperatures.
My concern over this paper is that it does not show how poor the signal-to-noise ratio of these proxies are nor concern itself greatly with the large uncertainties is using such temperature proxies.
The historical record is not yet supported by such a study.
CORRECTION.
This interpretation of the historical record is not yet supported by such a study.
I note, your grace, that the final encomium for this study in your linked page states that
"Others, including Mann, have used similar methods to put together detailed reconstructions of global temperatures during the last 1000 years. Going back 2500 years is "a very substantial contribution," says Mann."
The paper can thus be comfortably consigned to the dustbin of "climate science"
"The climatic turmoil coincided with political upheaval and waves of human migrations. By AD 500, the western Roman Empire had fallen."
One man's coincidence is another man's causation. Has anyone previously suggested the fall of the Roman empire caused climate change?
From the abstract quoted above: "Historical circumstances may challenge recent political and fiscal reluctance to mitigate projected climate change."
If they keep finding 'evidence' that current conditions are within the realms of natural variability it will do no such thing. If we make the changes that are being advocated for how will we validate the projections?
One passage that PaulM quoted from the report caught my attention:
"Historical circumstances may challenge recent political and fiscal reluctance to mitigate projected climate change."
If only the Romans had a Met Office to give them advice history might have turned out quite differently. They could have established a system of green taxes which would have prevented the collapse of the western Roman Empire and poor Edward Gibbon would have had to find something else to write about!
Does that mean Julia Slingo is the new Senna the Soothsayer.
woe woe and thrice woe
Says it all and saves one the trouble of reading the paper: the politics is prior.
We've only just been discussing the sloppy and partisan use of proxies in paleoclimate reconstructions, so this is timely.
I said on the 'update the proxies' thread that paleoclimatology needs an injection of rigour. This is what I am talking about.
A case can certainly be made that the Iraq War was caused by global warming. After all, the war was partly to do with oil, and oil is a fossil fuel, and as any fule kno, burning fossil fuels causes global warming.
Can I claim my Warmist badge, colouring book and huge research grant now, please?
As Frosty suggests, dendrochronology is a crock of manure because: -
1. Tree growth is affected by at least three factors other than temperature
2. Tree growth doesn't have a linear relationship with temperature.
Surely, as the "hide the decline" email showed, you can make tree ring data show or conceal anything at all, simply by deleting whatever data doesn't fit your hypothesis?
Very odd - access to this paper requires an additional payment beyond my institution's subscription - and par for the course is a tab marked "Supporting Online Material" - which when clicked reveals "Not Found - Content not found"
It's deja vu all over again.
I agree with Frosty - how any serious journal can consider publishing such dendrochronological dross is beyond belief.
As Frosty suggests, dendrochronology is a crock of manure because: -
1. Tree growth is affected by at least three factors other than temperature
2. Tree growth doesn't have a linear relationship with temperature.
Jan 14, 2011 at 11:49 AM | Stanford Rivers
And
3. Trees only grow in the summer so tree ring data only identifies temps etc in the growing season.
BOFA
European larches don't grow in hot summers. They grow in wet summers and in warm winters.
It would appear that the three minima of the Little Ice Age, 1650, 1770, and 1850, occur at the same time as the expansion of the British Empire. It is only with the onset of 20th century warming that the British Empire started to falter.
We Brits must love the cold.
Are we talking about Dendrochronology or Dendroclimatology?.
I thought dendrochronolgy was respectable and was used to correct carbon dating.
With dendroclimatology there appear to be too many factors influencing tree growth to produce a useful signal.
The lead author is interesting, his details are here: http://www.buentgen.com/
He is 34, his 1st degree was in Geography, Geology and Cartography, awarded his PhD in Nov 006 and between 2003 and Dec 2010 has published 70 papers with another bunch in review/press. That's on paper about every 7 weeks by my calculation. Even more interesting is the list of research "foci":
Climate Variability: MWP, LIA, Recent Warming, Color-preservation, Forcing agents
Early Instrumental Measurements: Homogenization, Urban-Heat-Island, High-elevation observations
High Mountains: European Alps, Carpathian arc, Pyrenees, Caucasus, Scandinavia and Tien Shan
Landscape Dynamics: Change and persistence in Alpine environment, settlement and building history
Palaeoclimatology: Long-term reconstructions, regional- to large-scale networks, frequency domains
Plague dynamics: Climatic and environmental triggers of plague outbreaks in Central Asia and Europe
Population Ecology: Long-term insect outbreak dispersal and dynamics
Tree-ring Research: De-trending, Composite chronologies, Maximum Latewood Density
Vegetation Dynamics: Intra- to inter-annual growth responses to climate, tree-line dynamics
That's 9 major subject areas. Where does he find the time? Perhaps more pertinent, just how much intellectual resource does he put into any one area?
Where does he find the time?
Each paper regurgates the latest papers and adds a small nugget of new info, he gets to cite his mates whose count goes up and he gets another paper.
So every 7 weeks he gets one orginal thought, and the rest is copy paste and cite.
I read somewhere that Phil Jones achieves an output rate of 3 papers per week. Dr Büntgen has a long way to go.
cosmic
Dendroclimatology. Or as Steve McIntyre calls it: 'dendrophrenology'.
From the illuminating list of Dr Buntgen's 'reearch foci' provided by David Chappell above:
First, this is a frankly dilettante profile. Far too many 'foci' for comfort.
Second, some of them are revealingly deterministic (see quote). Dr Buntgen has clearly decided that 'climate and environmental triggers' exist for outbreaks of plague, and is now about the business of proving it. I'm guessing, but his interest in 'insect outbreak dispersal and dynamics' will have lots to do with infection vectors.
Typo above: 'research foci'
And apologies to Dr Buntgen, but I only do umlauts on Tuesdays and Wednesdays.
Cosmic
You are right. Dendrochronology is respectable. Basically reads the bar code of growth rings on a specimen of undated old timber by comparison to the standard pattern for the geographical region, painstakingly built from the best control into a chronology. Used for shipwreck timbers, heritage timber framed buildings and so on. Needs a good thick crossgrain sample spread of rings, at least 40 yrs worth, the more the better. Just dates the rings to the years, no climate interpretation.
Not having seen the article, having only read press, here are some passages from another account of the article:
"In contrast, the population of northwestern Europe's countryside grew during a period of stable climate conditions between A.D. 700 and 1000, and Vikings established new colonies in Iceland and Greenland."
"During parts of the 2,500-year period examined in the new study, "temperatures were as warm as they were in the 20th century," he said. "But in the most recent years, including the last decade, that warming seems to be unprecedented in the long-term context." "
It seems to me that these statements at least hint at a warmer MWP, and explicitly speak to times as warm as the 20th C, although the quote doesn't indicate whether that is the MWP. If not the MWP, then that would also be interesting.
These words need amplification. "The climatic turmoil coincided with political upheaval and waves of human migrations. By AD 500, the western Roman Empire had fallen.".
The phrase waves of human migration" seems to refer to the Germanic Ostrogoths, Visigoths and Vandals and the various other tribes described as the Huns. However, within the Roman Empire, there were demographic changes that had already weakened it.
Extract: The People That History Forgot. Ernest L. Martin, Ph.D. Chapter 11
Historians have recognized that a tremendous change of attitude and/or temperament took place in the people of Italy, North Africa (and even Spain and Gaul) between the 2nd century B.C.E. and the 3rd century C.E. The truth is, it wasn’t that the native populations (that is, the early Latins, Etruscans, Celts, etc.) changed their basic temperaments. Something very different happened. These areas of western Europe were deluged by great influxes of peoples from other areas of the Roman Empire, notably from the east. It wasn’t the temperament of the people that changed, it was the race. Simon Magus, in going to Rome, came among his own type of people. While in his time there remained a thin veneer of old Latin stock in the west, most of the population of Rome and Italy by the 1st century was made up of Chaldeans, Syrians, Phoenicians, Edomites and Samaritans. Italy, by the 1st century of our era, had become a Semitic country.
http://www.askelm.com/people/peo011.htm
Human geography is much more important than religion, because it continues to expand our knowledge the origins of humanity.
However, WATERMELONISM seeks to apply religious strictures to structured enquiry and would have us believe in worshipping not only the SCIENCE IS SETTLED myth, but also the dishonest high priests of the myth, such as Hansen, Mann, Obama, et al. That's anathema.
Reading "The People That History Forgot" as a straightforward secular history, Martin's book is quite thought provoking.
http://www.askelm.com/people/index.asp
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