By comparing today’s Nature paper to earlier versions I found just a few months old, it looks like some blame revisionism occurred after early discussions of this paper at NOAA in May 2012.
Over at Australian Climate Madness, Simon points out the coverage of the ABC for this new paper in Nature. He writes:
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Just as we must get rid of the Medieval Warm Period, the inconvenient Roman Warm Period must also be dealt with, and here’s a novel way of doing it: claim that it was man-made. In a single stroke, the RWP is scrubbed from the list of “natural warmings” that the planet has experienced in recent history, helping the Cause by demonstrating that it too was anthropogenic. The ABC reports:
A period covering the heyday of both the Roman Empire and China’s Han dynasty saw a big rise in greenhouse gases, according to a new study.
The finding challenges the view that human-made climate change only began around 1800.
A record of the atmosphere trapped in Greenland’s ice found the level of heat-trapping methane rose about 2000 years ago and stayed at that higher level for about two centuries.
Methane was probably released during deforestation to clear land for farming and from the use of charcoal as fuel, for instance to smelt metal to make weapons, says lead author Celia Sapart of Utrecht University in the Netherlands.
“Per capita they were already emitting quite a lot in the Roman Empire and Han Dynasty,” she says of the findings by an international team of scientists published today in the journal Nature (link to abstract). (source)
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Only one problem. Versions of this paper and slide presentation by the lead author in mid May 2012 make no mention of the Romans or Han dynasty whatsoever. Here’s the original abstract compared to the current one:
ORIGINAL – May 15th, 2012 at NOAA’s ESRL: (Source: http://www.esrl.noaa.gov/gmd/annualconference/abs.php?refnum=110-120409-A)
Isotope Variations in Atmospheric Methane Over the Last Two Millenia
T. Röckmann1, C. Sapart1, G. Monteil1, M. Prokopiou1, R.V.D. Wal1, P. Sperlich2, J. Kaplan3, K. Krumhardt3, C.V.D. Veen1, S. Houweling1, M. Krol1, T. Blunier2, T. Sowers4 and P. Martinerie5
1Institute for Marine and Atmospheric Research, Utrech University, Utrecht, Netherlands; 303-497-4988, E-mail: t.roeckmann@uu.nl
2Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, København DK-2100, Denmark
3Ecole Polytechnique Federale de Lausanne, Route Cantonale, Switzerland
4Earth and Environmental Systems Institute, Geosciences, Penn State University, University Park, PA 16802
5Laboratoire de Glaciologie et Géophysique de lEnvironement, University of Grenoble, Grenoble, France
Methane (CH4) is an important greenhouse gas that is emitted from multiple natural and anthropogenic sources. Atmospheric levels of CH4 have varied on various timescales in the past, but in many cases the causes of these variations are not understood. Analysis of the isotopic composition of CH4 preserved in ice cores provides evidence for the environmental drivers of variations in CH4 mixing ratios, because different sources and sinks affect the isotopic composition of CH4 uniquely. We have analyzed (δ13C) of CH4 in air trapped in Greenland ice cores over the last 2 millennia and find that the carbon isotopic composition underwent pronounced centennial-scale variations between 200 BC and 1600 AD without clear corresponding changes in CH4 mixing ratios. The long-term CH4 increase observed over this period is accompanied by a small overall δ13C decrease. Two-box model calculations suggest that the long-term CH4 increase can only be explained by an increase in emissions from biogenic sources. The centennial-scale variations in isotope ratios must be primarily due to changes in biomass burning, which are correlated with both natural climate variability including the Medieval Climate Anomaly, and with changes in human population, land-use and important events in history.
Now compare that original abstract presented to NOAA to the abstract of the paper in Nature being touted by the press on October 3-4, 2012:
Natural and anthropogenic variations in methane sources during the past two millennia
C. J. Sapart, G. Monteil, M. Prokopiou, R. S. W. van de Wal, J. O. Kaplan, P. Sperlich, K. M. Krumhardt, C. van der Veen, S. Houweling, M. C. Krol, T. Blunier, T. Sowers, P. Martinerie, E. Witrant, D. Dahl-Jensen & T. Röckmann
Nature 490, 85–88 (04 October 2012) doi:10.1038/nature11461
Methane is an important greenhouse gas that is emitted from multiple natural and anthropogenic sources. Atmospheric methane concentrations have varied on a number of timescales in the past, but what has caused these variations is not always well understood1, 2, 3, 4, 5, 6, 7, 8. The different sources and sinks of methane have specific isotopic signatures, and the isotopic composition of methane can therefore help to identify the environmental drivers of variations in atmospheric methane concentrations9. Here we present high-resolution carbon isotope data (δ13C content) for methane from two ice cores from Greenland for the past two millennia. We find that the δ13C content underwent pronounced centennial-scale variations between 100 bc and ad 1600. With the help of two-box model calculations, we show that the centennial-scale variations in isotope ratios can be attributed to changes in pyrogenic and biogenic sources. We find correlations between these source changes and both natural climate variability—such as the Medieval Climate Anomaly and the Little Ice Age—and changes in human population and land use, such as the decline of the Roman empire and the Han dynasty, and the population expansion during the medieval period.
Note that the two abstracts start out identically (highlighted in blue), and have similar language throughout presenting the isotope data, but that the Nature abstract has that added part about Roman empire and the Han dynasty.
In this slideshow presentation of the paper, http://www.esrl.noaa.gov/gmd/annualconference/slides/110-120409-A.pdf this graph from page 5 is quite telling:
As Simon points out on his blog:
The population, as the article goes on to say, was about 300 million, barely 4% of what it it today, and without any industrialisation apart from burning charcoal. I will leave it to you to consider the likelihood of such a tiny agrarian population having a significant effect on the climate.
The ABC’s coverage is similarly disingenuous. I’m not going to pay thirty bucks for the full article in Nature (if anyone has access, I would be grateful for a PDF), but eyeballing the tiny graphics published with the abstract (see above) seems to indicate that centennial scale changes in CH4 mixing ratio in the Roman period were in the order of a 20-40 parts per billion (that’s billion with a b). How the ABC can call this a “big rise in greenhouse gases” is unfortunately yet more evidence of agenda-driven journalism. It’s a tiny fraction compared with the industrial rise in CH4, which took mixing ratios to over 1800 ppb, yet the paper claims it is responsible for the significant warming that occurred around the time of the Roman empire?
The graph of CH4 compared to land use change seems like a good case of correlation:
But as we so often learn, when it comes to correlation, that does not always imply causation. Check out this multipanel graph from page 11 of the slide show:
Note graph “f” in red, which are temperature reconstructions from Moberg et al., 2005, Ljungquist et al., 2011, and try to find a correlation with Ch4 emissions in graph “b”.
From my view, there certainly doesn’t seem to be one that holds past 1000AD, when temperature started going down, but world population and land use increased. Likewise, correlation with transformed charcoal in “c” is weak as well.
The conclusion page 13 from the presentation seem pretty wishy-washy, especially the last point, where no specific blame is placed:
Conclusions
•Pronounced centennial-scale δ13C(CH4 ) variability in pre- industrial period
•Highly likely caused by changes in pyrogenic sources
•Correlation with NH charcoal index and anthropogenic land use rate of change
•Long term CH4 rise due to biogenic sources, and correlates well with land use data
•Both natural variability and anthropogenic activities may have influenced the CH4 budget in the pre-industrial period
The claim about the Romans and Han Dynasty seems quite a stretch when you actually look at the data/graphs. But as you can see in the ABC article, they don’t dare show you those things lest you draw conclusions of your own that don’t fit their narrative.
This might help you understand the motivation to start blaming the Romans and the Asians:
Atmospheric Physics and Chemistry Group
Dr Celia Julia Sapart
Master in “Climate Change”, University of East Anglia, Norwich (UEA), UK, 2006-2007
http://www.projects.science.uu.nl/atmosphereclimate/celia.php
Perhaps she got “Jonesed” into adding the part about the Romans and Han dynasty?
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>>“Per capita they were already emitting quite a lot in the Roman Empire and Han Dynasty,” she says of the findings…..<<
Problem is that there was much less humans2000 years ago than there is today. There were about 250 million people in year zero, and 7,000 million today.
So, after having flattended out the MWP and the RWP, there's still the prvious one, the Minoan warm period. Was that anthropogenic too? An interesting read:
http://sppiblog.org/news/claim-2010-tied-with-warmest-year-ever-lacks-historical-perspective#more-4123
Isotopes of oxygen analyzed from deep ice cores drilled in Greenland’s massive two mile thick ice sheets show that today’s “record warmth” is not even close to how warm it’s been in the recent past. These oxygen isotopes can act as a proxy or substitute for temperature. What they reveal is that the earth was much warmer than today for most of the last 10,000 years by 1 to 4 degrees Fahrenheit. The entire warming of the last 160 years is just 1 degree Fahrenheit, half of which took place between 1910 and 1945 when humans could not have had any effect. In fact these ice cores reveal that earth’s temperature has been rising for 200 years, rebounding from a 500 year cold period known as the “Little Ice Age.” Further examination of the ice core temperatures show that earth’s temperature peaked some 3,300 years ago in the Minoan Warm Period and has been falling ever since.
Let me think this one through. Methane levels rose and remained at a high level for around 200 years. What anthropogenic activity caused this? Deforestation and the anaerobic production of charcoal?
But charcoal is burned, converting it to carbon dioxide and ash. Methane breaks down in the atmosphere into water and carbon dioxide. It has a half life of around 8 years. And deforestation reduces carbon sinks. Yet we are told elsewhere that ice cores show carbon dioxide levels were stable for thousands of years prior to the Industrial Revolution. This despite the assertion that natural sinks cannot cope with increases in anthropogenic carbon dioxide and it hangs around for hundreds of years. This explanation doesn’t add up.
And why did the Roman Warm Period ever end? Why did all these extra anthropogenic GHGs not prevent global cooling and a drift into the Dark Ages?
How about an alternative theory. The Roman Warm Period was caused by natural events probably resulting in a reduction in average cloud cover. This warming produced a thawing of the tundra and the release of methane from frozen ground in regions such as Greenland. This period ended with the Dark Ages which were caused by natural events probably resulting in an increase in average cloud cover. This cooling produced a freezing of the tundra and choked off the release of methane. No anthropogenic explanation is necessary.
Vukcevic’s witch burning theory is excellent!! You are all missing an important point. Adding this little bit of BS about the Hans and the Romans is probably what made it a Nature paper in the first place. I don’t blame the author (much) for playing the hand she was dealt.
Eyeballing the graphs, a 20-40 ppb increase caused a .4C increase in temperature between 0 AD and 1000 AD. From then to now it has increased to 1800 ppb. Using my mystical “two-box model calculations”, the increase to 1800 ppb should have raised the temperature 10 degrees C. However, I haven’t included the positive feedback effect, so recalculation including those forcings in my mystical “two-box model calculations”, will surely show we are actually 45 degrees C warmer now. Hansen better add some more adjustments if he wants to support my model.
/sarc
So I suppose you could say that the change in salmon and elk populations causes the PDO statistic to flip. Yes. I get the logic now. No wonder springtime in NE Oregon is getting colder. The bat population is changing. Damn bats.
I’m not even going to warrant this with a discussion over historic facts. I will simply dismiss this “study” as very expensive toilet paper.
Yarmy says:
October 4, 2012 at 1:36 am
An excellent observation that means the cAGW crowd have painted themselves into a corner. Effectively, other than completely wiping out the human race, there is no solution to AGW if you follow their logic. We might as well take advantage of all that cheap energy that is available from fossil fuels anyway.
A minor edit is suggested:
“A period covering the heyday of both the Roman Empire and China’s Han dynasty saw a big rise in greenhouse gases, according to a new study.
The finding challenges the view that climate change junk science activists smoke too much crack.”
Let’s assume there is a causal correlation between the Roman Empire and a climatic “Roman Warm Period.”
Which is more likely?
That a horse drawn, sail and oar ship driven Roman Empire changed the earth climate from cool to warm, or
A natural variation in earth’s climate, a warm phase, created the Roman Empire with its bountiful harvests, water wheel driven grain and lumber mills and a need to build aquaducts to serve its growing cities?
There is a corrollary question? Was there a causal relationship between the fall of Roman Empire and Climate?
how would they whitewash the Holocene optimum, which was both longer in duration and warmer than either the MWP or the RWP, and saw the rise of civilisations?
Ok, I can’t resist.
The Romans managed to plant wine pretty far north (England) and in China culture and technology exploded. The MWP has its equivalent in Asia a well. Not only was wine being planted very far north in Europe (Denmark), in China and Japan culture exploded again, leading to the first novel of mankind. Which means, in both cases it was significantly warmer than today. Try planting wine today in Denmark or Northern England. it won’t really work, because it’s too cold.
Whoever wrote this study is trying to rewrite history. From my point of view as a Japanologist specialized in history these “scientists” are guilty of raping history and should be treated as such.
The Romans produced a lot of cement 2000 years ago (ref. “Roman Concrete”) and from what we can tell burned a lot of wood/charcoal to do it. Given cement production is 2nd to fossil fuel use on the CAGW hit list, I am surprised the paper didn’t make this link.
Next on the list…………The Holocene Climate Optimum. 😉 How these goons seem shocked that the tide is turning against them is beyond me.
It would be interesting to read about how the biosphere responded during the Roman Warm Period.
The Pacific Islanders were doomed during this time.
[behind the scene at Clima-clown Crisis Management meeting]
Fellow Clima-clowns, we’ve been exposed and are now in a similar position as Governor William J Le Petomane in the movie Blazing Saddles….”We’ve gotta protect our phoney-baloney jobs, gentlemen, we must do something about this immediately”. We can’t make the warm bumps disappear from the hockey stick handle…..any suggestions ?
Well….i did find some extra Methane molecules hiding in some ice cores….can we blame CH4 on the Romans….how bout also blaming the Hans ? ? ?
GREAT….but Romans and Hans is not scarey enough….we gotta blame the INDUSTRIALIZATION of those evil empires. HEY….why not rebrand this as the IRON AGE AGW ! ! ! And while we’re at it, we can rename that pesky Minoan Warming the BRONZE AGE AGW ! ! !
FANTASTIC….get this info to one of the UEA shills and into the phoney-baloney media ASAP ! ! !
OK. if we fast forward to today: 75% of the current interglacial the holocene period has been warmer than the last 20 years. It tends to runb in centuries so the 17th century was cold, the 18th century warmer the 19th century cold, the 20th century warmer, etc.. The period used by the AGW protagonists starts around 1850 – which was the coldest period in the entire holocene., so naturally post this period anything is going to be naturally warmer
What I find interesting is that the lead author on the first paper is the last author on the second paper. Usually when the second paper (from the same research group) is based off the data/conclusions of the first paper, the lead author on the first paper is given second or at least third billing…
The Cheefio had a great post on C4 and C3 pathway plants produce different C12 and C13 amounts.
http://chiefio.wordpress.com/2009/02/25/the-trouble-with-c12-c13-ratios/
And then there is this:
“Just a few days ago, only the second isotope study of millet consumption in the Roman Empire was published, by Pollard and colleagues in the American Journal of Physical Anthropology. In a small Romano-British cemetery in Kent (late 3rd-early 4th century AD), a salvage archaeology project uncovered a dozen burials that were simple in nature: only coffin nails and hobnails from boots were found in most graves. Among these simple farmers, though, was an individual with a surprisingly high carbon isotope value, so Pollard and colleagues undertook a dietary (C/N) and migration (Sr/O) study of the individuals.
The anomalous partially complete skeleton was that of a male over the age of 45 buried wearing hobnail boots. The individual’s nitrogen isotope ratio was a bit high (11.2 permil), indicating aquatic resource consumption, but was not higher than average for Roman Britain. His carbon isotope ratio from collagen, however, came in at -15.2 permil, in stark comparison to the average of the other individuals of -19.8 permil (see below). This difference may not seem dramatic until you factor in the standard deviation – variation within the d13C ratios of the others from the site was only 0.3! This person was therefore eating a whole bunch of C4 resources – millet, sorghum, or animals foddered on those grains.”
http://www.poweredbyosteons.org/2011/10/millet-eaters-of-roman-empire.html
Are there any straws left for the drowning man? Burning charcoal merely releases the CO2 captured during the hundred to three hundred years or so of the life of most trees.
Use Google Images and search for the lead authorette and see a picture of her in a large important lab space standing in front of a large important piece of scientific equipment. She is dressed in burly work gear and about to embark on an important scientific bit of inquiry by probing into the secrets of the past in order to understand the present and future.
Youth is so exuberant.
Following hard on the heels of the Roman Warm Period and the Medieval Warm Period was the Little Ice Age. A time when the world’s population was even higher. Man’s extra co2 was unable to prevent natural cooling. Oh damn!
The three carbon isotope excursions shown are actually positive (more 13C) against an atmosphere that is strongly biased toward 12C, (13C -47% of the Pee Dee zero). These excursions are very subtle by geological standards and at this sensitivity could concievably reflect human influence.
The trouble is we have learned that the isotope signature of fossil fuel burning is NEGATIVE, and the burning of the Eurasian forests should produce a negative signature as well. Trees are future fossil fuels.
More interesting than the machinations of greenhouse theologians is how the atmosphere is able to maintain its negative “excursion” and why the biologically redjected 13C seems to wind up in the ocean.
Lefties are famous, practiced, and successful at changing the game when they are not pleased with the outcome. They get away with it because the so-called watchdogs of the media let them – due variously to corruption, laziness, and ignorance.
This just in: New study in Nature suggests that paleo-indians, using Clovis points to chip ice from glaciers for margaritas, helped end ice age.
The Neolithic revolution was clearly a major mistake.
In fact, we can go further back for the source of our present-day ills. Our tendency to walk upright on two legs led to a superiority complex, a psychological perspective which separated us from the rest of Gaia’s species, allowing us to claim a right to exploit animals and all other resources for our own benefit.
There is only one solution – get back on your hands and knees people, and keep your eyes on the ground.
Copyright LooneyLewPress 2012 (publication pending as soon as I’ve bribed the editor).
Surprisingly, Seth Borenstein reports on a study showing scientific fraud increasing in several journals including PNAS and Nature articles.
http://news.yahoo.com/study-fraud-growing-scientific-research-papers-190641079.html
This Roman Warm Period study masquerading as science is more similar to the transparent propaganda employed by the Nazi’s in the 1930’s to achieve their political aims in the Rheinland, Austria, and Czechoslovakia, Real science or history it is not.