Al Gore’s hockey stick version (page 65 of the book “An Inconvenient Truth“) is taken from one of the many conflicting versions of Lonnie Thompson’s ice core data. Now there is an ongoing controversy about whether Thompson’s data is a temperature or precipitation proxy, with pretty much every other scientist except Thompson now viewing the data as more of a precipitation proxy.
There’s an interesting and symptomatic change in IPCC wording between the Second Draft and the Final Report, which has the effect of bringing the language more in line with Al Gore.
Here’s what Al Gore said:
Nevertheless the so-called global-warming skeptics often say that global warming is really an illusion reflecting nature’s cyclical fluctuations. To support this view they frequently refer to the Medieval Warm Period. But as Dr Thompson’s thermometer shows, the vaunted Medieval Warm Period (the third little blip from the left below) was tiny compared with the enormous increases in temperature of the last half-century (the red peaks at the far right of the chart).
Those global warming skeptics – a group diminishing almost as rapidly as the mountain glaciers – launched a fierce attack against another measurement of the 1000 year correlation between CO2 and temperature known as the “hockey stick”, a grpahic image representing the research of climate scientist Michael Mann and his collegatues. But in fact scientists have confirmed the same basic conclusions in multiple ways – with Thompson’s ice core record as one of the most definitive.
Here’s an attempt at replicating the graphic in Inconvenient Truth (using the decadal version from Thompson’s Climatic Change 2003 article, but as discussed elsewhere, there are many versions of Thompson’s data floating around and Thompson has refused to provide sample data to disentangle the mess).
IPCC on Tropical Glaciers
The IPCC has come down on the side that Thompson’s ice core data is a precipitation proxy as follows:
Stable isotope data from high-elevation ice cores provide long records and have been interpreted in terms of past temperature variability (Thompson, 2000), but recent calibration and modelling studies, in South America and southern Tibet (Hoffmann et al., 2003; Vuille and Werner, 2005; Vuille et al., 2005), indicate a dominant sensitivity to precipitation changes, at least on seasonal to decadal timescales, in these regions.
Where is the Dendro Truth Squad when we need them? Do you think that they can do ice cores as well? Based on the IPCC, Al Gore’s Hockey Stick is simply showing that there is increased precipitation in the 20th century in high altitudes. Of course the increased precipitation may be due to increased warming, but this interpretation of the Thompson ice cores tends to undercut the dire warnings of drought that crop up elsewhere. In the Second Draft, the IPCC continued on, observing that “apparently unprecedented” glacier decline was “possibly” associated with enhanced warming at high altitudes and that other factors besides temperature “can strongly influence” tropical glacier retreat.
Very rapid and apparently unprecedented melting of tropical ice caps has been observed in recent decades (Thompson et al., 2000; Thompson, 2001) (see Box 6.3), possibly associated with enhanced warming at high elevations (Gaffen et al., 2000), but other factors besides temperature can strongly influence tropical glacier mass balance (see Chapter 3).
The unqualified use of “unprecedented” – this could almost be an article in Nature – is an annoying habit that makes climate scientists sound like Creationists. Memo to climate scientists: the earth is more than 4200 years old. There is strong evidence that the Quelccaya glacier is less than 4200 years old and, in my opinion, the evidence for the existence of the Kilimanjaro and Mt Kenya glacier in the Holocene Optimum is virtually non-existent.
Comparing this sentence to the final version, we see that “possibly” has been changed to “likely” and the statement that other factors could affect glacier balance has been removed.
Very rapid and apparently unprecedented melting of tropical ice caps has been observed in recent decades (Thompson et al., 2000; Thompson, 2001; see Box 6.3), likely associated with enhanced warming at high elevations (Gaffen et al., 2000; see Chapter 4).
I haven’t seen the version of AR4 that was used in the SPM, so I don’t know whether these changes were made before the SPM or after the SPM. It would be nice to know if this particular change was made so that the Report conformed to the SPM or not.
Stable isotope data from high-elevation ice cores provide long records and have been interpreted in terms of past temperature variability (Thompson, 2000), but recent calibration and modelling studies, in South America and southern Tibet (Hoffmann et al., 2003; Vuille and Werner, 2005; Vuille et al., 2005), indicate a dominant sensitivity to precipitation changes, at least on seasonal to decadal timescales, in these regions. Very rapid and apparently unprecedented melting of tropical ice caps has been observed in recent decades (Thompson et al., 2000; Thompson, 2001) (see Box 6.3), possibly associated with enhanced warming at high elevations (Gaffen et al., 2000), but other factors besides temperature can strongly influence tropical glacier mass balance (see Chapter 3).
Climate Audit 
40 Comments
Did Gore really mark AD1400 as the Medieval Warm Period?
Yes. This doesn’t match his graphic exactly as he only has two little blips in the actual MWP. Hey it’s Lonnie Thompson – why would two versions ever be the same?
How can it be warmer now than the MWP are anthropoligists lying when they say viking farms are buried in permafrost?
Or to trust the Goracle???
Team logic.
Mark
Dear Dinosaur, you must be careful about some Viking legends. For example, Greenland is called this way because of an old marketing trick. Eric the Red probably wanted more people to move there and buy land, so he called the icy land in this nice way.
In Bohemia, I would say that the historical sources still claim the 14th century to be very warm. Charles IV, our beloved king in the first half of the 14th century, brought wine to Prague etc. Beer was what survived at most times, however. 😉
Even hussites in the early 15th century were eating grapes in Prague. Not sure how sweet they were and it could have been getting colder already but the early 15th century still couldn’t be that cold. At any rate, the people certainly gave up grapes in Prague pretty soon afterwards.
Gore is using “global warming” in a more general sense. It can also mean local raining, global cooling, local snowing, global blowing, and so forth, with every pair of neighbors in this list being positively correlated with each other if observed from the right, concerned angle. 😉
#5
There are several interesting articles on relationship of grape wines and temperature, including information of blog favourites of MWP, AGW, and LIA. I hope to research it this week. I remember in Botany discussing the finding of grape/vinyard presses in regions that then (1982) could not sustain vinyards, and believe it was associated with Vikings. If these regions cannot support wine grapes today as well, it raises some problems.
If true, this would indicate that the use of proxies that do not show MWP warmer than today must be incorrect because the grape/temperature relation has been proven (empirically) numerous times. It would be interesting if the Viking farm lands can be found that are currently located in permaforst, indicated by one post, are about the same time period (if they exist). Then the use of different criteria would show, MWP was warmer than today, and proxie models would need to be changed to reflect the revelant data. Of interest was one wine grape article that had the history and talked indirectly about LIA. Of course wine making would stop in a LIA..if it got cold it would have to. It might be interesting to check the proxies against the LIA and make sure the models show that as well. It may be that the current models do not do either the LIA or the MWP in an accurate manner making the claims of not only the past, but the claims for the present suspect. However, they could be corrected from historical data of wine growing.
Essentially the slant and gravamen of the NAS Report, as many noted here. This is the talking point the NAS Report provided for public discourse. Tactic: 1. Politiely criticize Mann’s work, 2. Validate it anyway by a specious selection of other proxy-type studies.
Gore could have added, “The hockey stick graphic is nevertheless a powerful image, so lookie here, I got one of my own!”
Once again the airbrush and newspeak crew has been hard at work. Nothing must dilute or contradict the new paradigm as articulated by the high priests of the IPCC. All dissent will be crushed, marginalised and held to ridicule.
Am I paranoid, or is McCarthyism making a comeback? “Are you now or were you ever a Climate Sceptic?”
Re 1/2: Gore’s graph is not the Thompson ice core graph as he states; it is the Mann et al (1999) reconstruction composited with the Jones et al (1999) record. The graph above is similar to Fig. 7-c in Thompson et al (2003), the ice core composite. However, in the book version of AIT and the movie version I think as well, the graph matches Fig. 7-d, Mann and Jones data.
I’ve found that nearly every graph Gore uses he misrepresents; either the data is not from the stated source, or the data does not primarily represent climate influences as claimed.
RE: #8 – For the love of Big Brother, all that is true and correct, shall have been processed by the Ministry of Truth and will be seen on your telescreen – LOL
Following Lubos at #5 and John Pittman at #6, please forgive a layman butting in.
Sometimes the most accessible and convincing proxy is the historical record, and it happens that here in Britain we have a lot of that. When William the Conqueror landed in England and ended the Anglo-Saxon ascendancy it was 1066 by the Christian calendar. William commissioned a tax assessment of England, including every peasant, his oxen, his sheep – and his vineyards. Tax collection is the third oldest profession, and Billy’s assessors were very thorough.
The result was the Domesday Book, now online in various versions. My time is unfortunately limited so I have not been able to pursue this point in detail, but the search facility tells me that there are 55 references to English vineyards in the Book. That is an impressive datum: the vineyards disappeared later and have only returned in recent decades, after some hard efforts and not I think in such numbers.
The graph above claims 1066 to be the coldest point of the temperature series. I submit that the Conqueror’s time was the high point of the MWP, and Gore is a charlatan.
I believe, but don’t have the sources, that there is similarly impressive evidence from another, then greater civilisation. Can anyone confirm a Chinese fleet sailing across the north coast of Russia to Norway about the same time?
Lubos, maybe those Vikings fell for a hard sell, but they might just have sunk their spades in cold Greenland soil.
6, 11: The Team’s answer to this is that the Roman Warm Period, MWP, LIA, etc. are all “localized phenomena.” Seriously, I am just amazed that anyone would present a proxy that contradicts written history, but the Team seems to have no problem whatsoever in rewriting history.
Thanks Jeff #11
Discussion of Hopkins from Chapter 1,Geographical Ecology, MacArthur, Harper&Rowe, 1972:
Hopkins bioclimatic law is that the 3 oF cooling of 1000 feet of elevation is very roughly equal to 100 miles of lattitude. The derivation of adiabatic lapse for cooling rate is approxiamtely constant. Add every point on the earth gets the same average timelength of twelve hours per day, but not the same amount of energy due to latitude or altitude, we now can make a quick hypothesis: the average increase/decrease in energy (temperature) can be estimated using the decrease in wine production (LIA) and the 20th century increase in wine production using Hopkins bioclimatic law, also estimates of the average temperatures for MWP can be obtained.
http://www.winebusiness.com/GrapeGrowing/webarticle.cfm?dataId=43868 has a nice graph about grapes and temperature.
From: http://www.english-wine.com/history.html At the time of the compilation of the Domesday Survey in the late eleventh century, vineyards were recorded in 46 places in southern England, from East Anglia through to modern-day Somerset. By the time King Henry VIIIth ascended the throne there were 139 sizeable vineyards in England and Wales – 11 of them owned by the Crown, 67 by noble families and 52 by the church. It is not exactly clear why the number of vineyards declined subsequently. Some have put it down to an adverse change in the weather which made an uncertain enterprise even more problematic. Others have linked it with the dissolution of the monasteries by Henry VIII. Both these factors may have had some part to play but in all probability the decline was gradual (over several centuries) and for more complex reasons. AND An ever-increasing number of pioneers followed these leads and especially during the 1960s, 70s and 80s there was a rapid increase in the number of English vineyards to a figure well over 400 by the late 80s/early 90s. The total area under cultivation rose to more than 2,000 acres.
Looks like a workable historical proxie just using England.
See the discussions on grape phenology surrounding the publication by Chuine et al.
Thanks bender. I wonder why 1978 was blank. I was also interested in D.J. Keenan writeup of Chuine et al. My post #13 was more than just temperature sensitivity. Rather it was about more generalized model and for use of multiple data sets. Of interest was the article I read (will look up again) where grapes and wine were grown for consumption eastwards. I think it was around Bulgaria. The grape business supposedly ended due to LIA.
But my post was a way to add not just grapes but also my #6 post as related to supposed Viking farms in areas of perma-frost. The importance of agricultral records and taxes I had forgotten (thanks Jeff). I would look for lattitude and altitude advances and retreats of domesticated crops at the edge of temperature viability. Several of the articles were about increases of crops correlating with temperature increases. I am suspicious of yeild as a variable and would want to set temperature as the limiting factor.
Assuming the data could be obtained, compute the increases/decreases as temperature changes using the Hopkins bioclimatic. Example, say in the past 250 years, temperature had risen 3 oF, I would expect to see the limts of viability for several sources and different species, say grapes and wheat, to have proceeded 100 miles of lattitude, or 1000 feet increase elevation, or an equivalent, say 50 miles and 500 feet increase elevation. However, I think that I would have to use negative yield trend to extinction. Or the progression (say vinyards) into regions where it had been extinct and was now starting to become viable again.
Reading of several of the problems of tree ring data such as depending on which slope the tree grew, tree ring size may indicate precipitation more than temperature. Looking for viability limits set by assumed temperature limits was to reduce or eliminate the problem with tree rings. I have noted for tree rings temperature, nutrients, adverse weather, and other factors have been shown to effect tree ring size.
Jeff,
Gavin Menzies’ theories about globe-trotting Chinese admirals have been pretty well debunked, e.g:
http://www.1421exposed.com/
Wow, some very interesting suggestions regarding the existence and state of vineyards in England. I’m sure once the Team gets wind of this we will hear some “sour grapes.”
Sorry.
Actually, over at RC Gavin has posted on English vineyards as a proxy:
http://tinyurl.com/f6s6m
His argument seems to be that because English viticulure is flourishing now (oddly I’ve never tasted an English wine), viticulture in the MWP was not unusual. Stripped down, Gavin’s presentation seems to amount to: warm MWP…LIA…warm 20th century, much like the “cartoon” in the first IPCC report.
According to Gavin, viticulture is a poor proxy for temperature because it is multifactorial (unlike tree-rings, which apparently exhibit a linear relationship with temperature).
I love how in climate science, reconstructions trump historical records.
#18, James,
Well, as much as we may hate to admit it, using vineyards as proxy may not be the best proxy …
Let us be honest, but no real studies have been done there. Obviously vineyards need some temperature, but it is indeed multifactorial.
However ‘we’ don’t need vineyards to ‘prove’ there was a MWP with temperatures at least comparable to today’s temperatures (within the large error-margins that exist!). There is a lot of other evidence for that.
James #16
Many thanks for the correction on the Chinese fleet. Pity though – made a great story.
There isn’t a lot of English wine on the market, and they don’t seem to send it up here to Scotland for the likes of me to taste. Rumour is that it is dry in type, and best drunk in sparkling form.
I don’t understand more than about 10% of what this Board says, but really appreciate the sense of honest enquiry about the place.
Armin,
I was having a bit of fun with Gavin staing that viticulture is a poor proxy for temperature, when the same arguments apply to tree-rings.
#20 – Buckfast ‘Tonic Wine’ is English, and consumed largely by youngsters and jakeys up here in Scotland!
Yesterday there was a wine tasting of Dutch wines on Television (Tros Radar)
http://www.trosradar.nl/?url=PHP/news/9/3480
The white wines are from the south using traditional grapes like Riesling.
The red wines are from vineyards in Central Netherlands using new grape varieties that are mould resitant and (as a side effect) are better suited to colder temperatures.
So I like to know which grape varieties are cultivated in Britain.
I have a vague memory of learning in school that wheat varieties were modified to make it grow in the Canadian Prairies and I assume that something similar might well have been done with wines – so it’s possible that 20th century boundaries may differ from 11th century. Also I seem to recollect that, after some sort of disease pretty much wiped out European grapes in the 19th century, North American roots were used to hybridize or something like that. I’m sure a reader would know. Maybe that would affect the north boundary of grape growth?
Re 24: Growing wine grapes in cold Canada.
It takes more than a warming climate to grow where no man has grown before.
Missouri grapes are examples of hybrids that were bred to tolerate harsh climates. Many are based on Italian or German grapes, but the climate in Missouri is much less stable. Excruciatingly hot summers, very high humidity, but quite cool spring and fall temps to boot. Winters are traditionally rather cold as well, colder than in Italy or Germany. Yet still I drink that wonderful juice coming from Missouri wineries! 🙂
Mark
For English wines and grape varieties grown currently see this
I think a lot of these varieties are new especially the red grape varieties. The white wines seem to be similar to German wines.
Vines which do well in western Washington state USA would probably do well in the UK as well, especially in southern England.
Re: #24
European wine grape vines were devastated in the late 19th century by phylloxera probably brought over from North America. Grafting vitis vinifera to North American root stock as well as hybridization with native North American varieties was used to restore wine grape production in Europe. See:
http://en.wikipedia.org/wiki/Phylloxera
for example.
One point to keep in mind is that grapes for wine is different than grapes growing. The varietals spoken of are for harsh conditions. The problem for making wine is one of sugar content. The grape can grow well but not be much for wine. At one time in the distant past around (1940) it was stated that wineries did not occur past a certain lattitude. Not grapes, just they did not have enough sugar to be commerical in nature. Although temperature can be harsh, the varietals appear to be about weather condition not temperature. Other than reaching the point the vine cannot grow, the lack of warmth is about sugar and wine not growth or grapes. The good news is that there was a Spanish meeting on IPCC4 and what are the poor vinyards going to do when the best area for growing grapes heads up to England. Not to worry read of another vinyard site that said now is the time to invest because IPCC4 meant soon they would be in the best wine producing region.
#26
Pardon my ignorance. I did not know that Missouri produced wines. Now I am intrigued.
What are they like?
Steve, I realise this is not the forum for a discussion on wine. But just this once …
That is why in #14 I pointed to the Chuine thread. There are threads for grapes (harvest volume, harvest date, sugar content, etc.) as a climate proxy.
Outstanding, but I’m biased given that I went to school in the Ozarks, and grew up in St. Louis. My favorite is a Norton from Stone Hill Winery. My brothers and I once even did a road trip to Hermann (many wineries there) for their version of “Octoberfest” which ended rather… well, the three of us shouldn’t drink together. 🙂
A particularly interesting grape is the one they use to produce the Canadian “Ice Wine.” I have seen a special on it (Discovery or something) and they harvest the little dudes while _frozen_. Seems odd. I have not had the wine yet.
Mark
It is sweet because the sugar content goes through the roof as a result of freezing. And expensive because it takes a lot of grapes due to low amount of juice you get from a frozen grape. I think global coolers in the 1970s were predicting that ice wine one day will be grown in Florida.
Yeah, they said that if they let the grapes thaw in the sun, the sugar deteriorates within the day. As a result, they harvest in the dead of night. Gotta pay them harvesters big bucks for that. 🙂
Mark
Some current grape varieties have been bred to withstand much colder conditions. There are some wine grapes that will wistand -40 centigrade winter temperatures, developed by the U. of Minnesota. The northward migration of grape growing in recent times in NA is he result of improvements of cold resistance in varieties and growing techniques. Care should be taken to eliminate the possible effect of these variables before the acceptence of grapesas atemperature proxy.
#36
Yes, but the interesting part is not about temperature proxies in modern times but reliable estimates of temperature in past times of LIA and MWP. And note we will assume that the lab developed strains did not exit as one of our working assumptions.
i read all blogs mostly about to making wine in these tempreture proxy and interesting in grape wine. i
am also a wine blog lover.
The relative suppression of the English mediaeval viticulture was largely a political matter. It is rather too long to quote directly, but you will find a discussion of it at:
http://www.numberwatch.co.uk/2006%20March.htm#vino
Getting back to the science: What are we to make of the fact that much of the world is in a panic over the fact that the temperature of the Earth is now roughly equivalent to its 3000-year average, having risen about .8ºC since the end of the Little Ice Age 150-200 years ago? Reflecting on Robinson and Soon’s representation of Sargasso Sea temperature history, temperatures were colder than they had been for about 1,500 years. It is from this relative trough that we have emerged. Viewed from this historical perspective, our current temperature history is relatively unremarkable, which is why Mann and Gore had to distort it to make their case, and add the GCMs at the end of the historic record to accentuate it. And, overwhelmingly, neither the general public nor the media can recite either the current average temperature or its historical context. Instead we hear meaningless anecdotes (e.g. 2004 was the warmest year in X years) from “presentists” caught up in the moment.
Interesting, the Mann “hockey stick” graph, as it appeared in the 2001 IPCC report, is reproduced in a recent book published by the American Bar Association entitled “Global Climate Change and the Law,” edited by Michael Gerrard. While Gerrard admits in his introductory chapter that “this depiction became controversial,” he quotes approvingly the NRC which concluded “with a high degree of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries.” Again, a meaningless statement when viewed against the Little Ice Age history. One would have thought that our recent 1970s experience with predictions of a coming ice age would have cautioned the doomsayers, but they never seem to learn. Lawyers, of course, stand to make a good living off the complex regulatory schemes imposed by local, state, federal governments, which is why lawyers Gerrard et al accepted the global warming hype and worked backwards to supply the “evidence.”
Kudos to Steve and Ross for discovering the flaws in Mann’s research methodology.