This is a translation of the interview with Reinhard Bohm that I mentioned a few days back. Many thanks to the reader who provided it. There are a couple of places where the meaning of the German original is unclear.
It is a great pleasure for me to be able to introduce to you one of the most well know Austrian climate scientists, Dr Reinhard Böhm from ZAMT(the Central Institute for Meteorology and Geodynamics). Dr Böhm is regarded as a well respected expert in the field of climate research, in particular for climate modelling of the Alpine region. (You can dowload his CV here with a selection of his publications). Dr. Böhm is a much sought-after guest commentator and interviewee for the mainstream media, (among others, Wiener Zeitung, Der Standard).
It was of particular interest for me to interview Dr. Böhm, since I regard his statements with regards to his scientific work, as being truly compliant with the scientific ethic. This would be better expressed through metaphor: Imagine Diogenes, the Greek cynic - in a metaphorical sense - at a congress of climate scientists appearing with a lamp vainly searching for a climatologist and loudly insisting, that someone should point out one to him. One would point unhesitatingly to Dr. Böhm. As one of the few scientists in his field, he incessantly lobbies, in true aristotolean tradition, for a workable middle ground between climate alarmism and skepticism, in order not to loose all sense of reason.
William of Baskerville: Dear Dr. Böhm, I regard myself as honored that you could find the time to give me an interview. A heartfelt thank you for that!
Dr. Böhm: Thank you very much for your "being honored" - I think of it as self-evident to be able to find time for discussions about climate change. If nothing else, the length of your questions convinced me. I'm no friend of inappropriate summaries, which only in exceptional cases are able to do a complex subject justice.
Please allow me to offer a small reappraisal of the praise you've heaped upon me. I believe I am one of the few in my field who stand for reason in the debate about climate. Maybe too few do that in public. Many due to a lack of time (which i can understand, since the "climate debate" has taken us completely off guard), many through bad experiences, many perhaps due to uncertainty, of which the scientific expert is always wary.This is nevertheless construed negatively in the public arena.
Referring to your image previously from antiquity, had Herr Diogenes used a microphone rather than a lamp at the climate conference, he would have picked up many rational and critical conversations - scientific in essence.
William of Baskerville: Everyone is talking about climate science. Only a few years ago climatology probably ranked, in terms of status, alongside an underwater basket-weaving course and the well educated lay person would only have heard of Dr. Hubert Lamb, the then doyen of climate science, by chance. From this condition of scientific understanding, hardly appreciable to the outside world, emerged the science of climatology at the very latest by the beginning of the 90s. The well known German climatologist Hans von Storch wrote:
Up until the 1980s the dynamics of climate were the main focus of climate research, but since the 1990s it has revolved around the threat of climate catastrophe and climate protection. (Link)
Von Storch attempts to capture this change of state - from a purely internal scientific dialogue, devoted to discerning the truth, to a new condition which appropriates and intermingles with extraneous political subject matter - with the term "postnormal".
Personally I see here the effects of the application of the postmodern body of thought ("panfictional disappearers of reality" - [see explanation in the comments]) to the scientific method. This "change in paradigm" can probably be viewed as being partly responsible for the well renowned and widely accepted phenomenon known as the medieval warm period, first described by Dr. Hubert Lamb in 1965 and confirmed a hundred times and even expanded upon by the IPCC, being expunged from our collective memories through a handful of studies (Mann et al. 1998, 1999). Deming said
Decades of work was overturned by one journal article. The MWP had been reinterpreted out of existence. (Deming, D.: Global Warming, the Politicization of Science, and Michael Crichton's State of Fear, in: Journal of Scientific Explorations, Vol. 19, No. 2, 249, 2005).
Today, more than 10 years afterwards, we see climatology split in to several camps. On the one side those who believe they recognize a looming apocalypse (Polar bears becoming extinct, coastal towns being flooded, melting poles etc.) and, on the other side, those who view any statements about the warming of the earth as being bereft of any scientific evidence. In the middle are those scientists, who however, because of the politically charged atmosphere, find hardly anyone who will listen to them.
Could you convey to my readers the situation as you see it, from your position as an expert and as a simple citizen. Where do you see the causes for this situation, the aberrations within climatology and in particular, where would you start to correct the problem.
Dr. Böhm: When one knows one's own area of speciality inside out, the only perspective remaining is the one "inside looking out". I don't believe anyone who ever claims to be able to totally divorce himself from his/her own perspective and see the world from an entirely impersonal point of view - and thereby objectively. The simple citizen that you ask for, who views everything impartially, I will only claim to be when the discussion revolves around things of which i have no expert knowledge. For example, how one extracts greenhouse gases from the atmosphere, whether human society in the next hundred years will come together, or whether it will become more heterogenous, what influence the climate had on the journeys the Vikings made to Greenland and Labrador and similar things.
And at this point we have already come to the very core of the matter,that which the whole climate debate suffers from: On both sides of the apparently unreconcilable positions of extremity we find so-called experts writing and talking about things in which they are not expert. They should be allowed to do so of course, otherwise there would be no public debate and I consider it to be one of the highest ideals of a democratic and free society. But they should do so on a level playing field and not from a position of being a self proclaimed expert on the subject.
I know how hard it is, not least because the boundaries are not sharply defined but remain nebulous. I start with myself and in truth I probably have a superior level of knowledge about modeling the climate of the Alpine region, but my expertise does not lie in climate modeling, but in quality control and data analysis. That however fits in well with your specific questions relating to the MWP.
William of Baskerville: Herr Dr Böhm, let's talk about the subject of my blog. I deal explicitly with the question of what scientific evidence there is for the claim that a global medieval warming period existed. In the light of my research, I have come across a lot of "peer-reviewed-papers", in which evidence for the existence of a MWP for the Alpine region is cited. At the same time diverse proxy data has been collated, in part to form "multiproxy-reconstructions".
To name but a few examples - Holzhauser et al.: Glacier and lake-level variations in west-central Europe over the last 3500 years, in: The Holocene 15, 6, 2005.(abruf-/ downloadbar [pdf-Format, 1 MB] unter: Glacier and lake-level variations in west-central Europe ...)
- Giraudi: Late Holocene glacial and periglacial evolution in the upper Orco Valley, in: Quaternary Research, 71, 2009.(abruf-/ downloadbar [pdf-Format, 1,1 MB] unter: Late Holocene glacial and periglacial evolution ...)
- Mangini et al.: Reconstruction of temperature in the Central Alps during the past 2000 yr froma y180 stalagmite record, in: Earth and Planetary Science Letters 235, 2005.(abruf-/ downloadbar [pdf-Format, ca. 190 KB] unter: Reconstruction of temperature in the Central Alps ...)
- Büntgen et al.: Summer Temperature Variations in the European Alps, A.D. 755-2004, in: Journal of Climate, Volume 19, 2006.(abruf-/ downloadbar [pdf-Format, ca. 1,6 MB] unter: Summer Temperature Variations ...)
With reference to the above I would like to talk about one of your projects, in which, as described in the prospectus, for the first time a reconstruction of the climate of the last thousand years has been made. It concerns the project ALP-IMP (see http://www.zamg.ac.at/forschung/klimatologie/klimawandel/alp-imp/
Would you like to tell us more exactly about how this project started and in due course the results of this research project with respect to the evidence for the existence of a medieval warm period in the Alpine region?
Dr. Böhm: In the EU project ALP-IMP (Overarching program, http://www.zamg.ac.at/alp-imp), I was lucky enough to have the opportunity to lead a research project, in which European institutes , ranging from renowned to highly prestigious, participated. The main objective was the climate reconstruction of the last millennium, the designated region being the Alpine region. The sought after techniques were instrumental capture of data (I), climate modeling (M) and indirect climate analysis. (Proxies and hence the P from IMP). The project ran for three years (2003-2006) and brought a "harvest" of 50 peer reviewed publications. Very good and professional results were achieved(and that was really "unique" as the prospectus describes) through a co-analysis of thousands of tree rings sets from the region. From the temperature sensitive trees along the treelike , the project partners of the WSL-Institute in Birmensdorf in Zurich(Kerstin Treydte, Jan Esper, Ulf Buentgen, David Frank), the university of Innsbruck (Kurt Nicolussi) and the BOKU-Vienna (Michael Grabner, Sofia Leal) were able to form a reconstruction of the summer temperatures in the Alps right back to the year 755 AD and down to a temporal resolution of one year. Our project colleagues from the CRU of the university of Norwich (Dimitrios Efthymidais, Phil Jones, Keith Briffa) were able to show, through a combination of using their own world-wide encompassing CRU-dataseries and our collated data(HISTALP- dataseries of the ZAMG), that the temperature curve from the high regions in the Alps is representative of large parts of continental Europe and that the the temperature curves for winter or the entire year could not be extrapolated from the measurements made, that were limited to the summer growing months.
I have tried - perhaps this is somewhat boring for the reader - to be precise , in order to render the following statement more accurately:
Yes , we have been able to demonstrate the existence of a medieval warm period through large regions of middle europe for the summer and early autumn periods, that ( and this was new) clearly existed in two particularly warm phases in the 10th and 12th centuries that were split by a cooler period, and which then subsided. The following centuries brought a gradual cooling to a small ice age, whose core period, from around the late 16th until the early 18th century, was 2 degrees C colder than both of the warm centuries of the MWP. A clear warming up began in the second half of the 19th century that culminated in a maximum in the middle of the 20th century, that achieved the same temperature levels seen in the warmest centuries of the MWP. The entire recent warming trend of the 80s and 90s has at least attained the same level of warming as the warmest decades of the MWP. The minor differences between the warmest decades of the MWP and the current warm periods lie within the bounds of uncertainty for both indirect and direct climate data. (large interannual variability, homogeneity problems, non-climatic influences on the proxies etc.)
William of Baskerville: Dr. Lamb spoke not only of middle europe in his publications, but his statements on this subject extended also to Europe and the northern hemisphere, more explicitly to Greenland. Numerous studies of past days, speak, what I find to be, a clear language. I can cite more than 50 studies for Europe (2003-2010). For the northern hemisphere Greenland and Iceland are highlighted in the following studies.
- Dahl-Jensen et al.: Past Temperature Directly from the Greenland Ice Sheet, in: Science, Vol. 282, 9. October 1998.(abruf-/ downloadbar [pdf-Format, ca. 620 KB] unter: Past Temperature ...)
- Vinther et al.: Climatic signals in multiple highly resolved stable isotope records from Greenland, in: Quaternary Science Reviews, Volume 29, Issues 3-4, February 2010.(Abstract abrufbar unter: Climatic signals in multiply highly ... )
- Paul et al.: Diatom-inferred climatic and environmental changes over the last ~9000 years from a low Arctic (Nunavut, Canada) tundra lake, in: Palaoegeography, Palaeoclimatology, Palaeoecology, Volume 291, Issues 3-4, 15. May 2010.(Abstact abrufbar unter: Diatom-inferred climatic ...)
Schließlich eine Studie zu Island: - Ran et al.: Diatom-based reconstruction of palaeoceanographic changes on the North Icelandic shelf during the last millennium, in: Palaoegeography, Palaeoclimatology, Palaeoecology, Article in Press, Corrected Proof. (Abstract abrufbar unter: Diatom-based reconstruction ...)
Do you regard Lambs statements with regards to the northern hemisphere as having been verified? What is the current scientific thinking, is there a consensus?
Dr. Böhm: Yes, there are a large number of well conducted analysis, that confirm the existence of the MWP over a large area. The variation in amplitude between the MWP-LIA is smaller, the greater the measuring area becomes - a matter of course, that arises from the diversity of regional aberrations from the average measured over this area.
Since the Hockeystick-reconstruction by Mike Mann et al (1999), a large number of further reconstructions have been attempted that had the entire northern hemisphere as their objective. As is typical in science, the more exact an object is analyzed, the more the results diverge from one another. We have now arrived at the "Spaghetti curves" from the dogma of the "Hockeystick" , where the amplitude MWP-LIA lies between 0.3 and 1.0 degrees C. In order to enliven this dry description, I have added a diagram of the Hockeystick and the "Spaghettis".[4] To be more precise it relates to one of more than 80 short contributions, that our group made available on the website of the ZAMG (http://www.zamg,ac,at), forming part of our hopefully most extensively rational and objective "morsel of information" relating to the climate debate. Take the "infobits" over the climate of the last millennium as a kind of sneak preview.
William of Baskerville: When we go beyond Lambs statements, although Lamb actually cited evidence "from the arctiic to New Zealand" (Cf., Lamb: The early medieval warm epoch and its sequel, in: Palaoegeography, Palaeoclimatology, Palaeoecology, 1: 14ff.), the question still remains, whether the MWP was a global phenomena. Once again dozens of studies appear to be unequivocal:
Several have been selected , but not representatively:
- Tandong et al.: Temperature and methane records over the last 2ka in Dasuopu ice core, in: Science in China, Vol. 45, No. 12, Dezember 2002.(Abstract abrufbar unter: Temperature and methane records ...)
- Demezhko und Golovanova: Climatic changes in the Urals over the past millennium - an alnalysis of geothermal and meteorological data, in: Climate Past, 3, 2007.(abruf-/ downloadbar [pdf-Format, 8 MB] unter: Climatic changes in the Urals ... - ich rate jedoch, den Download von nachstehender Seite, mit "speichern unter", vorzunehmen: http://www.clim-past.net/3/237/2007/cp-3-237-2007.html)
- Cook et al.: Evidence for a 'Medieval Warm Period' in a 1,100 year tree-ring reconstruction of past austral summer temperatures in New Zealand, in: Geophysical Research Letters, Vol. 29, No. 14, 2002. (abruf-/ downloadbar [pdf-Format, 370 KB] unter: Evidence for a 'Medieval Warm Period' ...)
- Driese et al.: Possible Late Holocene equatorial palaeoclimate record based upon soils spanning the Medieval Warm Period and Little Ice Age, Loboi Plain, Kenya, in: Palaeography, Palaeoclimatology, Palaeoecology, Volume 213, Issues 3-4, 21. October 2004.(Abstract abrufbar unter: Possible Late Holocene ...)
Also interesting is one of the very recent eclectic works by Ljungqvist "Temperature proxy records covering the last two millennia: a tabular and visual overview" (der Abstract abruf-/ downloadbar [txt-Format, ca. 1,3 MB] unter: Temperature proxy records covering the last two millennia), in which he arrives at the conclusion, after an initial evaluation of 71 "proxy-series", that the MWP can be classified, based on solid evidence, as a global phenomena. From the abstract:
Here, the first systematic survey is presented, with graphic representations of most quantitative temperature proxy data records covering the last two millennia that have been published in the peer-reviewed literature. In total, 71 series are presented together with basic essential information on each record. ... Both the Medieval Warm Period, the Little Ice Age and the 20th century warming are clearly visible in most records, whereas the Roman Warm Period and the Dark Age Cold Period are less clearly discernible
When one considers that it revolves around a multitude of different proxies, starting with treerings and ending with (Ice)coredata and the Lambian period (ca 900-1300 AD) …??..then it appears to me that there remains no more doubt, that there is strong scientific evidence the MWP was a global phenomena - although strongly differentiated temporally and spatially. What is your assessment with regards to this?
Dr. Böhm: When you call it "strong scientific evidence for the existence of a global MWP' , then I agree with that. There is no doubt about it. If you had said, like the extremists on one side happily state, that the MWP has clearly exceeded the current temperatures, then I would have had to contradict you. That is not "state of the art". The fundamentalist fraction on the other side talks down the MWP with glee ……[?? the rest of this sentence is really not intelligible]
The reason why it is possible to disagree about the global extent of the MWP and the global "amplitude" of the MWP-LIA is because unfortunately we don't have the requisite density of proxies, despite a number of available proxy sets, because many of the proxies are only seasonal, and this seasonality for natural proxies is biased towards summer periods, and because historical documents in the first half of the century are very thin on the ground. These shortcomings in global proxies that reach back to the MWP have to be dealt with using sophisticated statistical techniques, about which there is still no real consensus.
Last but not least a comprehensive physical understanding of climate variability over a thousand years and more is dependent upon external climatic forcings being documented beyond reproach (which unfortunately is not yet clear as evidenced by the furious debate over the climatic forcing via the Sun). Only then can climate simulations over a period of more than 1000 years back in to the past be calculated on powerful supercomputers, through which questions such as the cause-and-effect mechanisms of the MWP, LIA and the current warm period can be rationally explained.
I don't want to put people off till the cows come home. The future has already begun. Just recently in the climate hosting centre in Hamburg a 7000 year long simulation with the model ECHO-G has been carried out and the anlaysis has just begun...