China’s 2,000 Year Temperature History
While Mann claims his hockey stick science to be “vindicated”, we have this from World Climate Report, a new peer reviewed study that illustrates that the current warm period we live in is neither unique nor unprecedented. They also manage to point out the key issue, the uncertainty of proxies such as used by Mann et al. – Anthony
We constantly hear that the warmest years on record have all occurred in the most recent decades, and of course, we are led to believe this must be a result of the ongoing buildup of greenhouse gases. In most places, we have approximately 100 years of reliable temperature records, and we wonder if the warmth of the most recent decades is unusual, part of some cyclical behavior of the climate system, or a warm-up on the heels of a cold period at the beginning of the record. A recent article in Geophysical Research Letters has an intriguing title suggesting a 2,000 year temperature record now exists for China – we definitely wanted to see these results of this one.
The article was authored by six scientists with the Chinese Academy of Sciences in Beijing, the State University of New York at Albany, and Germany’s Justus-Liebig University in Giessen; the research was funded by the Chinese Academy of Sciences, National Natural Science Foundation of China, and the United States Department of Energy. In their abstract, Ge et al. tell us “The analysis also indicates that the warming during the 10–14th centuries in some regions might be comparable in magnitude to the warming of the last few decades of the 20th century.” From the outset, we knew we would welcome the results from any long-term reconstruction of regional temperatures.
The authors begin noting that “The knowledge of past climate can improve our understanding of natural climate variability and also help address the question of whether modern climate change is unprecedented in a long-term context.” We agree! Ge et al. explain that:
“Over the recent past, regional proxy temperature series with lengths of 500–2000 years from China have been reconstructed using tree rings with 1–3 year temporal resolution, annually resolved stalagmites, decadally resolved ice-core information, historical documents with temporal resolution of 10–30 years, and lake sediments resolving decadal to century time scales.”
However, the authors caution “these published proxy-based reconstructions are subject to uncertainties mainly due to dating, proxy interpretation to climatic parameters, spatial representation, calibration of proxy data during the reconstruction procedure, and available sample numbers.”
Ge et al. used a series of multivariate statistical techniques to combine information from the various proxy methods, and the results included the reconstruction of regional temperatures and an estimate of uncertainty for any given year. They also analyzed temperature records from throughout China over the 1961 to 2007 period and established five major climate divisions in the country (Figure 1).
Figure 1. Types, lengths, and locations of proxy temperature series and observation used in the Ge et al. study. The five climate regions were based on a “factor analysis” of the 1961–2007 instrumental measurements. Grey shading indicates elevation (from Ge et al., 2010).
The bottom line for this one can be found in our Figure 2 that shows the centennially-smoothed temperature reconstruction for the five regions of China. With respect to the Northeast, Ge et al. comment “During the last 500 years, apparent climate fluctuations were experienced, including two cold phases from the 1470s to the 1710s and the 1790s to the 1860s, two warm phases from the 1720s to the 1780s, and after the 1870s. The temperature variations prior to the 1500s show two anomalous warm peaks, around 300 and between approximately 1100 and 1200, that exceed the warm level of the last decades of the 20th century.” The plot for the Northeast shows warming in the 20th century, but it appears largely to be somewhat of a recovery from an unusually cold period from 1800 to 1870. Furthermore, the plot shows that the recent warming is less than warming that has occurred in the past.
Figure 2. Five regionally coherent temperature reconstructions with 100-year resolution; the dashed line is the part with fewer series used; and the solid line is the mean value. The shaded areas are the two coldest periods, during the 1620s–1710s and 1800s–1860s (from Ge et al., 2010).
The Central East region also has a 2,000 year reconstruction and Ge et al. state “The 500-year regional coherent temperature series shows temperature amplitude between the coldest and warmest decade of 1.8°C. Three extended warm periods were prevalent in 1470s–1610s, 1700s–1780s, and after 1900s. It is evident that the late 20th century warming stands out during the past 500 years. Considering the past 2000 years, the winter half-year temperature series indicate that the three warm peaks (690s–710s, 1080s–1100s and 1230s–1250s), have comparable high temperatures to the last decades of the 20th century.” No kidding – the plot for the Central East region shows that the warmth of the late 20th century was exceeded several times in the past.
Commenting on the Tibet reconstruction, Ge et al. state “The warming period of twenty decadal time steps between the 600s and 800s is comparable to the late 20th century.” In the Northwest, they note “Comparable warm conditions in the late of 20th century are also found around the decade 1100s.” Unfortunately, no long-term reconstruction was possible for the Southeast region.
In summarizing their work, Ge et al. report :
From Figure 3 [our Figure 2 –eds.] , the warming level in the last decades of the 20th century is
unprecedented compared with the recent 500 years. However, comparing with the temperature variation over the past 2000 years, the warming during the last decades of the 20th century is only apparent in the TB region, where no other comparable warming peak occurred. For the regions of NE and CE, the warming peaks during 900s–1300s are higher than that of the late 20th century, though connected with relatively large uncertainties.
We get the message – the recent warming in at least several regions in China has likely been exceeded in the past millennium or two, the rate of recent warming was not unusual, and the observed warming of the 20th century comes after an exceptionally cold period in the 1800s.
Declaring that anthropogenic greenhouse gas emissions have pushed modern temperature beyond their historical counterparts disregards the lessons of 2,000 years of Chinese temperatures.
Reference:
Ge, Q.-S., J.Y. Zheng, Z.-X. Hao, X.-M. Shao, W.-C. Wang, and J. Luterbacher. 2010. Temperature variation through 2000 years in China: An uncertainty analysis of reconstruction and regional difference. Geophysical Research Letters, 37, L03703, doi:10.1029/2009GL041281.
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This is another of the many detriments from our own unethical scientists politicizing and distorting science. They’ve undermined the credibility of much of our scientific community while China demonstrates the results of honest science.
And it’s only getting worse.
This new piece by Lubchenco is pretty special.
Jane Lubchenco 4th of July special
http://www.open-spaces.com/article-v2n1-lubchenco.php
But for some extraordinary eco-babble check her 1998 work she links to. Both old and new are staggering reads.
http://www.sciencemag.org/cgi/content/full/279/5350/491
http://www.sciencemag.org/cgi/reprint/279/5350/491.pdf
IMO we have eco-loons heading our science institutions.
And Mann 2009 shows that central China was one of the warm areas. So…
It seems like this study confirms the findings, not contradicts them.
It will be hard for the warmers to come up with arguments against this. It appears that they used several sources (tree rings, sediments, stalagmites) and more than 1 sample of each.
No problem. Just add Mannian data weighting and a dash of Mannian PCA.
A penny will get you a pound that if you fed the data through the hockey stick algorithm you’d get a hockey stick.
This comment is made in ignorance of details, but arises from past reading of blogs. Is it possible that the Tibetan Ice cores shown are among those whose raw data are being withheld by Lonnie Thompson? Anyone have connections and speciality to track this down? The resolution of the map above is inadequate to pin down a named location.
Maybe the downturn in the proxies not matching the recent warming is because the yamal trees don’t grow in urban centers or near airports?
So this is the event that Prof. Mann was trying to prepare us for in his interview on Panorama (BBC).
I thought that his unusual humility and jaw-droppingly unlikely remarks that his Hockey Stick had been overplayed were out of character and presaged some events for which he was preparing his defence. And I guess this is one of them.
Oh dear! If the research in the article is shown to be robust, then he has nowhere to go. If the MWP has been reinstated in China, then together with known historical evidence from Europe/North America, a fair chunk of the Northern Hemisphere is shown to have experienced it.
And yet Mann’s (in)famous reconstruction fails to show it at all…he had successfully removed it from the record as per the e-mail ‘We must get rid of the Medieval Warm period’. Is this becasue of methodological errors as described by McIntrye and McKitrick, from cherry picking the data, or just sheer bad luck that the data samples that Mike used didn’t happen to show it?
Because if there was a Medieval Warm period, and it was about as warm as today. the thesis that CO2 as the sole contributor to warming must fail. If it was as warm 600 years ago, when CO2 levels were much lower (about 70% of current), then it cannot be argued that it is only the CO2 increase that has caused the atmosphere to warm. Indeed there must be other factors, because it clearly got colder after the MWP..and at a time when CO2 was stable (or possibly gently increasing).
And as all the climate models since the Hockey Stick in 1998 have universally assumed that CO2 is the bad guy, then they too are shown to be fundamentally wrong. (which might explain why their agreement with real world observations is so poor).
The fallout from this paper will take a long time to work through. No wonder Anthony kept it up his sleeve as a little surprise for us all while he was travelling. But it most definitely isn’t good news for the more Alarmists among the Warmers. Be prepared for a deluge of criticism from the usual suspects…no doubt focussing on imagined unpleasant characteristics of the Chinese people/government/motivations.
But just rememebr ine simple thing. if shown to be true, the paper shows teh MWP is back. And all the CAGW theories fail because of it
AGW’ers will say the chicoms are just trying to justify their coal-burning ways.
Steve Oregon says:
July 4, 2010 at 10:11 pm
“And it’s only getting worse.
This new piece by Lubchenco is pretty special.
Jane Lubchenco 4th of July special
http://www.open-spaces.com/article-v2n1-lubchenco.php
Thanks Steve. just read it. Yep, according to her the debate is still over…
“To summarize this brief summary of climate changes, it’s clearly erroneous and patently ridiculous for anyone to assert that there is no scientific certainty in this area. The IPCC represents the collective expertise and judgement of over 2000 of the most knowledgeable climate scientists in the world. Their conclusions carry substantial weight and are the definitive assessment.”
And she was actually appointed to some important position by the Obamites, wasn’t she? Sigh.
Mann’s study (and various follow ups) were referring to the last Millenium, and the NH mean temperature (with some seasonal biases). As interesting as the new 2000 year chronology is, it in itself does not invalidate or contradict the Mann reconstruction. It’s pretty well known that various regions in the world have experienced warmer and cooler periods over the last millenium. Whether these are co-incident, and whether they are large-enough scale to have a big impact on the hemispheric mean is another question altogether, and one that is not answered by this paper.
This is the temp record for China, not the globe. It’s a small fraction of the northern Hemisphere. One of the key points in most reconstructions of NH millennial temps is that warming happened at different times in different regions, with as much as 500 years between warm events. This oft-referenced skeptical web page on the MWP can be checked to see that at while it is hot in some regions, at the same time it is cool in others.
http://pages.science-skeptical.de/MWP/MedievalWarmPeriod.html
This paper on a fraction of the landmass of the Northern Hemisphere is not a silver bullet for the conclusions of Mann et al and other Northern Hemispheric temp reconstructions that followed. Or did Mann say something specific about China in his millennial reconstructions?
Why should we believe Chinese scientists who are obviously in the pay of Big Coal?
Surely Obummer, Dave Boy, Buff Huhne and Prince Chuckles have made everything clear?! no?
These wily orientals are obviously just looking at weather, not climate!!
Worse than we thought!!!!
‘It’s pretty well known that various regions in the world have experienced warmer and cooler periods over the last millenium. Whether these are co-incident, and whether they are large-enough scale to have a big impact on the hemispheric mean is another question altogether, and one that is not answered by this paper.’
Fair comment….no paper anywhere has yet attempted to work out the impact on the hemispheric mean..apart from the famous one with the Hockey Stick, where it was apparently demonstrated that there were no significant fluctuations before about 1900. Anywhere. No matter what the historical records said.
And it sort of makes me want to ask..what practical use would the derivation of a real hemispheric mean be (even if we could all agree on how to measure it in a representative way?)
Plants don’t grow according to the hemispheric mean..they grow according to the local conditions that they experience. Grapes didn’t grow in Yorkshire because Algeria was warmer or cooler or the same, they grew because Yorkshire was warmer.
Ice caps don’t grow or shrink according to the hemispheric mean they change according to the local conditions that they experience.
Sea levels because of thermal expansion may change based on the global (not hemispheric) mean. but the haven’t been doing anything at all worrying … we’ve lived with 1 foot per century increases for a long time without even noticing (depth of one standard housebrick every two generations — big deal).
Apart from as a statistical artefact, what use would a true hemisipheric mean be to us? I’m genuinely puzzled. Because after about 40 years of supposedly dangerous global warming I have yet to see any of the dreadful consequences predicted. Lots and lots and lots of scare stories about what is going to happen…but no actual real proven bad consequences.
Huh? You just quoted something that gainsays your point.
You understand that a definitive assessment from experts can encompass uncertainties? Lubchenko actually emphasises what some uncertainties are. She’s not saying the debate is over, she’s reminding us of the credentials of the scientists having the debate.
Amino Acids in Meteorites says: July 4, 2010 at 9:46 pm “Would you do the work and submit it for publication?”
I am not close to the techniques used in dendrochronology data and modeling as a temperature proxy and, frankly, don’t trust it as a reasonable proxy for the historical climate and temps. All I would do is place the time-calibrated tree-ring data over the historical record of civilization and sea level data to find interesting correlations.
What I have done already is . . .
• put Fairbridge’s Curve over Usher’s history of human civilization. Quite interesting to say the least.
• take the Vostok record and overlay the genetic timing model(s) of right whale and killer whale speciation. It appears the Pleistocene climate flux led to the radiation of these cetacean genera and punctuated the emergence of new species. For these two very different genera (one baleen whale, one toothed dolphin), the points of speciation are very similar. I’d like to compare other genera (Lagenorhynchus in particular).
• overlay Bilal Haq’s Cenozoic sea level data (calibrated to the Gradstein GTS) on a comprehensive genus-level phylogeny of cetacean evolution. [Conclusion: major climate swings led to the extinction of prior forms and the emergence of new forms. This happened on generic and family-levels depending on the severity and abruptness of the climate changes.]
If someone with a good handle on the dendrochronology data and results wants to work with the sea level data and historical record used in my previous comparisons, I’d be interested in the collaboration.
That is simply untrue. There are some here.
http://agwobserver.wordpress.com/2009/09/08/papers-on-the-mwp-as-global-event/
This is a fairly well-known one.
The Spatial Extent of 20th-Century Warmth in the Context of the Past 1200 Years (PDF)
Ben says:
July 4, 2010 at 6:22 pm
“To think on this Fourth of July where we in the USA celebrate our freedom that a Chinese study puts to question our scientific and media bias…
Kind of ironic and sad.”
“The article was authored by six scientists with the Chinese Academy of Sciences in Beijing, the State University of New York at Albany, and Germany’s Justus-Liebig University in Giessen.”
I’d like to remind you that it was mainly the Americans who liberated Germany and helped us establish a stable democracy. Your influence is not lost.
Marty Singh said:
“July 4, 2010 at 11:45 pmIt’s pretty well known that various regions in the world have experienced warmer and cooler periods over the last millenium. Whether these are co-incident, and whether they are large-enough scale to have a big impact on the hemispheric mean is another question altogether, …”
As I understand them, Dr Mann’s various papers are open to exactly this criticism. Even if taken at face value, they do not establish that the ‘hockey stick’ applies over the large scales contemplated by your own comment. Would you agree?
Before the food fight starts I’d like to reference http://www.worldclimatereport.com/index.php/2010/06/21/spinach-lovers-rejoice/
History teaches us a lot of lessons-in this case about climate. Too bad that history seems to be a blind spot for many people.
Tonyb
Brad aka 1personofdifference says:
July 4, 2010 at 8:35 pm
Is anyone else getting tired of hockey sticks and the IPCC and the CRU?
Anyone got any good fishing stories yet this year? I hope I get a job before August because I’m dying to hook into a nice big fat Chinook or Silver this fall. I haven’t been in two years and i’m literally shaking with withdrawls.
As a long time observational student of human beings, their behavioural trends and the psychology of crowd behaviour, I have noted that the rather strident “intelligent lay person” who accepted the scientific “consensus” without question, and applied and labeled sceptics with the worst of motives seem to now want to disengage from their version of the “debate” and distance themselves and change the subject, a version of the three wise monkeys now that its becoming clearer that things are not as they were when their “science reigned supreme.
Unfortunately the tide of debate may be turning against CAGW but the manipulators and those who set the agenda will still be waiting in the wings to impose social and political change or look for other opportunities to make money on other misfortunes.
I don’t suggest that you fit into any of those convenient “pockets” it is good to get away, do something you enjoy and recharge the internal energies, we learn by our experiences and become wiser and more alert to the scammers of the world.
Enjoy your holiday respect the environment and above all catch some fish!!
You have an example of medieval warm period and LIA from the Southern hemisphere here:
A quantitative high-resolution summer temperature reconstruction based on
sedimentary pigments from Laguna Aculeo, central Chile, back to AD 850
Lucien von Gunten, Martin Grosjean, Bert Rein, Roberto Urrutia and Peter Appleby
The Holocene 19,6 (2009) pp. 1–9
or here: http://www.climatestudies.unibe.ch/students/theses/phd/24.pdf page 90
Dirk H, your comment re mainly America liberating Germany is both offensive and inaccurate. May I remind you that America wriggled and fought against entering both world wars until a) WWI was pretty much done, and b) when she was forced into WWII by the enormous loss at Pearl Harbour. Great Britain’s former Colonies of Australia, Canada, New Zealand, South Africa and others fought alongside the Brits from the beginning of both wars and the NZ government mistakenly declared war on Germany in 1939 hours before the Brits did, by getting the time difference for their declaration wrong. Many valiant Americans fought and died for a free world in both wars before America followed, but to over-claim America’s war record is jingoistic, ill-informed and divisive. If you were to research Gen. Dwight Eisenhower’s orders of the day for the Normandy Landings, you might be surprised by his humility.
It’s interesting to see that the only time when all five regions show significant warming at the same time is the late 20th Century onwards…
And please remind me again when the MWP is supposed to be… I thought the point was that it was supposed to be warm everywhere at the same time. Figure 2 above actually disproves the MWP as the NE region is cooling as the othertwo regions are warming up.
YMMV.
Can I echo echo Alexander K’s re Dirk H’s comment, most commentator’s refer to the Allies’ success, not any one country. I’d also like to add that I don’t think the German’s saw it as liberation, certainly not at the time. I know one German civilian who was about 3 at the time of the “liberation”. Her next year was spent living with her mother at starvation level in an allied internment camp near the Danish/German border.
Back on topic, irrespective of the nationality of the scientists or the political stance of their political leadership, I hope the paper will be evaluated on its merit as a piece of peer reviewed research.
“New Chinese study in GRL disputes the hockey stick conclusions” (?)
How can that be when Mann’s hockey stick conclusions aren’t just about China, and he acknowledges regional differences?
Quoting from Mann’s 2009 study:
“The Medieval period is found to display warmth that matches or exceeds that of the past decade in some regions, but which falls well below recent levels globally.”
http://www.meteo.psu.edu/~mann/shared/articles/MannetalScience09.pdf
Did Mann say China’s has recently been warmer than anytime during its “2000 year temperature history” ? If not, the article about the GLR study errs in concluding the study disputes the hockey stick conclusions.