The Medieval Warm Period linked to the success of Machu Picchu, Inca Empire

According to Wikipedia,  the Medieval Warm Period was a time of warm weather around AD 800-1300 during the European Medieval period. Initial research on the MWP and the following Little Ice Age (LIA) was largely done in Europe, where the phenomenon was most obvious and clearly documented. It was initially believed that the temperature changes were global. However, this view has been questioned; the 2001 IPCC report summarises this research, saying

“…current evidence does not support globally synchronous periods of anomalous cold or warmth over this time frame, and the conventional terms of ‘Little Ice Age’ and ‘Medieval Warm Period’ appear to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries”.

Of course, there’s many researchers, such as Michael Mann and his thoroughly discredited “hockey stick”  that  try mightily to make the MWP disappear.

MWP-hockey-warming_graph

News flash to IPCC.  Now a scientist has linked the MWP to success of the Inca civilization in the southern hemisphere. It is not going away any time soon, it is spreading.

The new study is called “Putting the Rise of the Inca within a Climatic and Land Management Context” and was prepared by Alex Chepstow-Lusty, an English paleo-biologist working for the French Institute of Andean Studies, in Lima. Link to paper (PDF) is here (h/t to WUWT reader Corey)

Here is the abstract:

The rapid expansion of the Inca from the Cuzco area of highland Peru produced the largest empire in the New World between ca. AD 1400–1532. Although this meteoric rise may in part be due to the adoption of innovative societal strategies, supported by a large labour  force and standing army, we argue that this would not have been possible without increased crop productivity, which was linked to more favourable climatic conditions. A multi-proxy, high-resolution 1200-year lake sediment record was analysed at Marcacocha, 12 km north of Ollantaytambo, in the heartland of the Inca Empire. This record reveals a period of sustained aridity that began from AD 880,  followed by increased warming from AD 1100 that lasted beyond the arrival of the Spanish in AD 1532. These increasingly warmer conditions allowed the Inca and their predecessors the opportunity to exploit higher altitudes from AD 1150, by constructing agricultural terraces that employed glacial-fed irrigation, in combination with deliberate agroforestry techniques. There may be some important lessons to be learnt today from these strategies for sustainable rural development in the Andes in the light of future climate uncertainty.

Here is a news article about it that talks of the findings. (h/t to WUWT reader “cotwome”) – Anthony

Huayna Picchu towers above the ruins of Machu Picchu

Opportunity knocks, again, in the Andes

by Nicholas Asheshov
The last time global warming came to the Andes it produced the Inca Empire.  A team of English and U.S. scientists has analyzed pollen, seeds and isotopes in core samples taken from the deep mud of a small lake not far from Machu Picchu and their report says that “the success of the Inca was underpinned by a period of warming that lasted more than four centuries.”

The four centuries coincided directly with the rise of this startling, hyper-productive culture that at its zenith was bigger than the Ming Dynasty China and the Ottoman Emachu_picchu_globempire, the two most powerful contemporaries of the Inca.

“This period of increased temperatures,” the scientists say, “allowed the Inca and their predecessors to expand, from AD 1150 onwards, their agricultural zones by moving up the mountains to build a massive system of terraces fed frequently by glacial water, as well as planting trees to reduce erosion and increase soil fertility.

“They re-created the landscape and produced the huge surpluses of maize, potatoes, quinua and other crops that freed a rapidly growing population to build roads, scores of palaces like Machu Picchu and in particular the development of a large standing army.”

No World Bank, no NGOs.

The new study is called “Putting the Rise of the Inca within a Climatic and Land Management Context” and was prepared by Alex Chepstow-Lusty, an English paleo-biologist working for the French Institute of Andean Studies, in Lima.  Alex led a team that includes Brian Bauer, of the University of Illinois, one of today’s top Inca-ologists. The study is being published in Climate of the Past, an online academic journal.

Alex spends a lot of time in Cuzco and he told me the other day that the report “raises the question of whether today’s global warming may be another opportunity for the Andes.”

The core samples from the sediment of the little lake, Marcacocha, in the Patakancha valley above Ollantaytambo, show that there was a major cold drought in the southern Andes beginning in 880 AD lasting for a devastating century-plus through into 1000AD.  This cold snap finished off both the Wari and the Tiahuanaco cultures which had between them dominated the southern Andes for more than a millenium.

It was at this same time that the Classic Maya disappeared in Yucatan. It was also a time, on the other side of the Pacific when major migrations from East Asia took place into Polynesia, an indication of a major Niño event; a Niño sees western Pacific currents switch to flow from West to East.

Core samples from glaciers and from the mud beneath lakes in the Andes, the Amazon and elsewhere have built up a history of the world’s climate and the message is crystal clear. It is that changes have taken place in the past, during the six or seven thousand years of our agriculture-based civilizations, that are just as big as the ones we are facing from today’s CO2 warming.

The message may be, too, that climate change is especially forceful in the Andes. Here we are, sandwiched thinly between the world’s biggest ocean and the world’s biggest jungle. The peaks are so high that they have had until just a few years ago deep ice on or near the Equator.

The valleys and surrounding hills have formed the roof of the human world for at least three millennia, according to Alex Chepstow-Lusty’s core samples. Nowhere else do millions of people live at or even near 4,000ms above sea level where it is cold, but getting warmer.

Today’s warming is also following on a colder spell that started, the core samples say, not long after the arrival of the Spaniards in the 16th century.

For instance, the pollen in the cores says that there was maize being grown under the Incas around the lake at 3,300ms a.s.l. Until recently the upper level for maize around the Urubamba valley was 3,000-3,100ms. In the past few years the maize level has moved up and today there is maize being grown again above Marcacocha.

Alex’s records show that hundreds of terraces were being built around the lake between 1100 and 1150 AD -“lots of mud followed by the heavy pollen of maize.”

Enrique Mayer, at Yale, tells me that “the question of the expansion of maize together with the Inca state is now a proven archeological fact, notably in the Mantaro Valley (Tim Earle).

“The question of why terraces are not worked now as intensively as they could has been worked on (Bill Devevan) in the Colca Valley where the terraces are actually in franco retroceso.

“Also, you have John Treacy’s book on Coporaque which is probably the most technically accessible to the argument that terraces are, like flower pots, expensive to maintain.”

There is also, of course, the work of John Earls on the terracing at Moray.

Today there are thousands upon thousands of fine flights of Inca terraces all over the upper ends of the valleys of Central and Southern Peru but few of them are used on a regular basis.

Efforts have been made, among them by Ann Kendall, the English archaeologist, to rescusitate the old irrigation channels and the use of the terraces in the valleys above Machu Picchu. But most have been re-abandoned.

In the same vein the great forests of polylepis, the world’s highest tree, which capture and conserve moisture, have mostly been cut down for firewood.

As they say, you only have to look in the mirror to see where the problem is.

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theduke
July 8, 2009 8:52 am

Apart from the fact that it presumes CO2 to be the cause of today’s warming, this is a very informative piece.

Curiousgeorge
July 8, 2009 8:57 am

Every day we hear of yet another piece of evidence that gives the lie to the IPCC et al , and the currently popular ( among politicians at least ) anthropogenic climate change conjecture. How much hard evidence, such as this, is it going to require to overcome the momentum this conjecture has built up over the last few years?

noaaprogrammer
July 8, 2009 9:12 am

…and don’t forget the rise & fall of cliff dwellers in the Southwest – e.g. the Anastasi people.

Chris Schoneveld
July 8, 2009 9:13 am

Alex Chepstow-Lusty’s work is just one of many studies that have confirmed the existence of the MWP in the SH.
http://www.co2science.org/subject/s/southamericamwp.php

Slide2112
July 8, 2009 9:14 am

Ah, so it was the Inca who caused the MWP…

Jon P
July 8, 2009 9:16 am

RealClimate (you know where where “real” climate scientists post, will analyze and comment on this paper in 3-2-1…..never…..

Evan Jones
Editor
July 8, 2009 9:20 am

fall of cliff dwellers
I can see how that would be a problem.

Steve Keohane
July 8, 2009 9:22 am

Anyone who follows paleo-anthopology knows that climate reconstructions are done at a lots of digs. Pollen, plant remnants and insects provide onfo on living conditions for the inhabitants. If you look at this for 40 years or so, you develop a feel for the natural variance of climate. This is why ten minutes in AIT, my wife shut it off, due to my ranting at Gore for showing time-truncated and outright fabricated temperatures for the past several centuries. Steve McIntyre validated my ascertions with analysis of Mann, Briffa, etc.

michel
July 8, 2009 9:27 am

Well, its just a matter of time before someone posts the argument that if the MWP existed, it is bad news for scepticism, because it will simply prove that the climate is more sensitive, not less, to CO2.
Quite how it is supposed to prove this has never been entirely clear. The proponents of the argument wisely avoid explaining.

Charlie
July 8, 2009 9:28 am

“RealClimate (you know where where “real” climate scientists post, will analyze and comment on this paper in 3-2-1…..never…..”
Let’s see which blogs reject this study since the authors aren’t climate scientists.
Facts are more “robust” than any theory. It may take a while, but facts do [u]generally[/u] win out.

Ric Locke
July 8, 2009 9:30 am

J. Christ on a pogo stick, can I get in on some of that grant action? I could sure use the money…
Show me a “lost city of ancient civilization” and there’s a huge chance it dates back to either the MWP or the Roman Warm. The Anasazi, as noaaprogrammer notes. Angkor Wat. Mapunguwe (in South Africa). The list goes on. Dangit, to the extent they can put dates on it, the Australian Aboriginal “Dream Time” matches! About the only negative version of that is Teotihuacan, which went away at about the beginning of the MWP — and that corresponds to the consolidation of Aztec culture and its subsequent rise.
Bah. It goes back to a question I’ve been asking since the beginning of the Gerbil Worming hysteria: What was the sea level in the Bay of Bengal in the year 1000?
Regards,
Ric

dkemp
July 8, 2009 9:31 am

Dr. Soon from Harvard published an article maybe 5-6 years ago, which contained no new work of his own but, instead contained a fairly long list of articles focusing on the LIA from authors around the earth. Dr. Soon’s article showed pretty clearly that from these other papers the LIA was a worldwide event and not just a US or European event. I think Dr. Mann shortly thereafter suggested, before Congress no less, that Dr. Soon shouldn’t be allowed to publish any more.

John Anderson
July 8, 2009 9:34 am

I suspect that the title would read better were it:
The success of Machu Picchu, Inca Empire linked to the Medieval Warm Period.
The original phrasing could lead some to believe the Incans caused the MWP, much as they think we are causing AGW today.
Sure, it sounds crazy, but so does AGW.

Paul Nikkel
July 8, 2009 9:37 am

Anthony:
What is the source for the bottom graph that you show below the Mann “Hockey Stick” in the introduction?

Ron de Haan
July 8, 2009 9:41 am

Interesting article.
Unfortunately all the debunked subjects keep on coming back in print and television broadcasts over and over again. It is a tiresome process.
Fortunately the MSN is punished severely.
People stop reading the papers, they stop watching stations like BBC, CNBC CNN, Discovery Channel, and National Geographic Channel.
They turn to the internet and make up their own mind.
This is the effect of OVERKILL and BIASED REPORTING.
The cold weather is a great help too.
The public knows when they are tricked into a scam and we should have more faith in their judgment.

pinkisbrain
July 8, 2009 9:47 am

if you have a look at this good overview:
http://www.co2science.org/data/timemap/mwpmap.html
you will find in almost every region of the planet the MWP, the times, the anomalies and so on…
i have no idea why m. mann could ever public his hockey stick and why an IPCC did so.

Patrick Davis
July 8, 2009 9:53 am

I understand The Moche existed before the Incas in, what is now, Peru between 100-800AD and their fall has been attributed to climate change. They already lived in quite a harsh environment, and when the climate changed, crops failed, it rained heavily, animals starved, they then started sacrificing humans (This has a familiar theme with today’s AGW crowd), when that didn’t “apese the God’s”, they, who were left, started fighting between themselves until, there were none.

Ray
July 8, 2009 9:53 am

Appart from that the author believes that today’s warming is from anthropogenic carbon dioxide, this article shows clearly that the temperature rise of that time period was global, and indirectly the following cold period. I still don’t really get it why the author still thinks that CO2 makes tmperatures go up? The record shows otherwise… and he does not say anything as to why it was warmer.

Douglas DC
July 8, 2009 9:53 am

Darn Inca and their SUV’s.Wait! you say they didn’t have the Wheel Ok they were tracked then! Believe!!

Steven Hill
July 8, 2009 9:59 am

shut up and pay the tax…….Barrack Obama has spoken

Austin
July 8, 2009 9:59 am

The Mongols expanded at the hight of the MWP.
The Hohokam culture collapsed at the end of the MWP during massive floods.
The Medieval Famine was in 1315-1317 and things did not stabilize until 1322. The Black Death followed in 1338.

Sam the Skeptic
July 8, 2009 10:00 am

I think the cliff-dwellers were actually Anasazi but I my be wrong. There is certainly evidence of a highly sophisticated culture (they changed their leaders according to the season!) which MAY have been unable to survive the LIA for reasons to do with over-population vs declining crop yields.
There is certainly enough evidence from elsewhere that the price of wheat varied in inverse proportion to the number of sunspots which adds to the argument that a) there was a medieval warm period — better yields=lower prices, and b) the climate then got colder — lower yields=higher prices.
I really have trouble working out why that is so hard for a scientist to understand, or at least include in the parameters of his research.

July 8, 2009 10:05 am

Besides, the MWP is validated by the records of iron stained grains, the same than the LIA. The percentages of sedimentary ISG are proportional to solar irradiance through a logarithmic function:
ISG% = |3362 [LN(TSI)]-24268|*1.94
For example, for a TSI of 1366 W/m^2, the proportion of ISG is 8.06%. The margins of error is -0.15 to + 0.15.
Taking into account a negative response to temperature, the MGW and LIA are beautifuly delineated when the ISG values are set in reverse order.
This formula is applied, of course, only for well known values of Total Solar Irradiance; for example, the satellite measurements of the intensity of TSI.

Conservative&denialist
July 8, 2009 10:09 am

This is quite interesting. Scafetta paper, presented at the EPA:Climate Change and Its Causes:A Discussion about Some Key Issues
Nicola Scafetta, Duke University
also talks about the same (slide #9).
There is something to add here: Up there in Macchu Picchu there is a sun dial stone called the “Inti watana”(from Inti=Sun and watana=which ties) to mark the solstice, however the Inca’s solstice holiday, the Inti-raymi or Sun’s holiday, is traditionally held in june 24th, so this holiday has 3 days back referred to the nowadays solstice june 21th; so if we take the difference in seconds we have 259200 seconds, that in turn divided by 52 arc seconds a year of equinoxes’ precession, we obtain the original date when this holiday was instituted is 4984.61 years back in the past. This is not surprising but only for those archeologists who do not have any knowledge of equinoxes precession. And this is not surprising because, near Lima City, the capital of Peru, it has been found an archeological site of that antiquity, Caral, built before the pyramids of egypt ( http://www.caralperu.gob.pe/nueva/principal.html ) where Quipus (pronounced “kee-poos” :Knot writing) have been found (Quipu was the first Inca writing, and, by the way, also the first writing taught by the first chinese terrestrial emperor Fu-Hi, as told by Walter A.Fairservis, in his book:The origins of Oriental Civilization-Mentor books collection, Ancient Civilizations)
It will be useful also to let you know that one of the main events in the Inti-Raymi conmemoration it is the lightning of a fire by using a concave mirror, so assuring that the sun is close enough to light it on.

Alan the Brit
July 8, 2009 10:09 am

Jon P;-)
Of course they’ll examine it but as “the duke” points out, it relies upon the presumption that CO2 is causing today’s apparently “unequivocal” warming!
Still, I bet it is an intersting read nevertheless, but it must leave some questions about today for some. Of course, it would a really good wheeze to change the colour schemes of those graphs, how about blue for hot & green for cold, that should confuse a few folks!
OT but Met Office is being very cautious about forecasting the remainder of the UK’s “sizzling summer” we’ve had a few days of. July supposed to be pretty awful – no change there then as it has always historically been a fairly wet month, August is supposed to get the “sizzle” apparently, will keep you posted! It must be a bit like gambling one is bound to win something eventually if you paly often enough but I fear they are on a hiding to nothing – again!

July 8, 2009 10:09 am

Near as I can tell, warmer weather is beneficial to life, plants and animals as well as humans.
Do we need any more proof that liberals are gripped with and motivated by cultural, societal and planetary suicide?
All life on earth is carbon based, viewing carbon as a “pollutant” and demanding its reduction and/or removal is nothing more than calling for extermination of all life. That is the end result of their programs and we need to see it for what it is.
It is time for a culture of life to assume control of the debate and the decisions.
Best regards,
Gail S
http://backyardfence.wordpress.com

Vincent
July 8, 2009 10:13 am

What’s wrong with these scientists? Don’t they know the MWP does not exist?
It’s all lies!

bill
July 8, 2009 10:24 am

What is amazing is that no-one will trust temperatures measured with instruments. Yet the headline graph shows temperatures to within 0.5degC back to times when temperatures were measured by hot, cold and ok!!
It is interesting to note that this temperature plot from an earlier blog entry
http://wattsupwiththat.files.wordpress.com/2009/07/kirkby_slide_siberianclimate.jpg
shows Siberian temperatures being 1degC below 20Century normals
And this plot of grape harvest date shows no shortened harvest times (compared to 2000+) Times (and so temperatures) are similar to those in 1650 to 1700
The LIA is missing from the grape dates as well – the plot at top shows LIA 1550 to 1700 but this period is similar to 1790 1900 in dates and therefore temperatures.
Life is so full of incosistencies!

SteveSadlov
July 8, 2009 10:38 am

No doubt the MWP was a world wide golden age for the emergence of mountain cultures. Alpenvolk, Tibettans, Mustangians, Nepalese, and the ones already mentioned. Then, when things got cold, they became scattered remnants. Their cultural oddities derive from that pattern of early development followed by a deep retreat and fall off in population.

Richard Heg
July 8, 2009 10:39 am

I linked to this article in a previous comment. This article is in the current national geographic about the city of ankor in cambodia. The city was at its hight around the 12th century at the hight of the warm period and fell due to lack of rain during the little ice age.
http://ngm.nationalgeographic.com/2009/07/angkor/stone-text

SteveSadlov
July 8, 2009 10:39 am

Argh … MWP.
REPLY: Fixed pre-argh, Anthony

Don S.
July 8, 2009 10:39 am

noaaprogrammer
Not sure who the Anastasi were. Google might ask “did you mean Anasazi?”
Sam the Sceptic
‘The Mayor of Casterbridge’ is a fine literary exposition on the effect of climate on wheat prices. Because of the way farm products were marketed in England, knowledge of weather precursors were avidly sought and drove the futures sales of grains. Still do. Want to know what the weather will be in East Anglia next fall? Ask a farmer. He’s betting his personal wealth on it.

Corey
July 8, 2009 10:40 am

Here is the study:
Putting the rise of the Inca Empire within a climatic and land management context
Received: 30 January 2009 – Accepted: 2 February 2009 – Published: 4 March 2009
Abstract
The rapid expansion of the Inca from the Cuzco area of highland Peru produced the largest empire in the New World between ca. AD 1400–1532. Although this meteoric rise may in part be due to the adoption of innovative societal strategies, supported by a large labour force and standing army, we argue that this would not have been possible without increased crop productivity, which was linked to more favourable climatic conditions. A multi-proxy, high-resolution 1200-year lake sediment record was analysed at Marcacocha, 12 km north of Ollantaytambo, in the heartland of the Inca Empire. This record reveals a period of sustained aridity that began from AD 880, followed by increased warming from AD 1100 that lasted beyond the arrival of the Spanish in AD 1532. These increasingly warmer conditions allowed the Inca and their predecessors the opportunity to exploit higher altitudes from AD 1150, by constructing agricultural terraces that employed glacial-fed irrigation, in combination with deliberate agroforestry techniques. There may be some important lessons to be learnt today from these strategies for sustainable rural development in the Andes in the light of future climate uncertainty.
http://www.clim-past-discuss.net/5/771/2009/cpd-5-771-2009.pdf
REPLY: Thank you sincerely for finding that, I spent time looking but was unable to. – Anthony

Corey
July 8, 2009 10:58 am

REPLY: Thank you sincerely for finding that, I spent time looking but was unable to. – Anthony
You’re welcome! Keep up the good work.

July 8, 2009 11:25 am

Gail S (10:09:58) :
Near as I can tell, warmer weather is beneficial to life, plants and animals as well as humans.
And biologists are sure of it. I do not understand why some colleagues adhere to the fallacy on the “toxicity of the carbon dioxide pollutant”. They do know for sure that life is not possible without carbon dioxide. In the begining of life, living beings were chemosmotic-anoxibiotic organisms. Life prospered in environments with more than 8000 ppmV of CO2 (proterozoic era).
In the middle proterozoic chemoautotrophic organisms appeared and by the late proterozoic the composition of the atmosphere started changing. The proportion of Oxigen increased due to the release of this gas from H2O through photosynthesis. The superwarm Earth during the proterozoic era is evidence against the role of carbon dioxide like an important “greehouse” gas.

George Tobin
July 8, 2009 11:30 am

I think the Incas suddenly realized it really could not really be that warm and pleasant because the Medieval Warming Period (if it existed all all) was limited to northern Europe–and their economy collapsed as a result of that realization.
It may also be the case that when believers in Inti (the sun god) starting to perceive that the god Illapa’s extreme weather events were actually a form of positive rather than negative feedback that the religious culture was fatally undermined as well.
Also, there is no truth to the silly rumor that Pizarro ordered Atahuallpa, last of the Incan rulers to be executed with a hockey stick.

Conservative&denialist
July 8, 2009 11:36 am

Thanks to Mr.Nasif Nahle (11:25:05) : we can guess that perhaps some
chemosmotic-anoxibiotic organisms are the ones after the “global warming” issue. 🙂

Barry Foster
July 8, 2009 11:45 am

Can someone guide me in the right directions? In this month’s BBC Focus magazine (here in the UK) they say that the Medieval Warm Period wasn’t global. But is the current warming global? Are there many places which show no warming, or even cooling since 1979? I know the lower troposphere shows no warming now, and neither does the Antarctic, but are there any other places? Thanks.

Michael D Smith
July 8, 2009 11:49 am

Thanks for the link… The comment about CO2 warming is not in the linked paper.

Edward
July 8, 2009 11:52 am

I marvel at people who still deny that there was a medeival warm period. There’s ample evidence of earlier warmer periods when people traversed Alpine mountain passes that are now covered by glaciers. The Romans did so as did the “Iceman” Otzi about 5300 years ago. Perhaps our climate is just now returning to a more normal warmer time period. Please find link below.
Thanks
Ed
http://news.bbc.co.uk/2/hi/science/nature/7580294.stm

tj
July 8, 2009 12:04 pm

Gail S., In answer to your question all “liberals” are not “…gripped with and motivated by cultural, societal and planetary suicide…” Liberals have been misinformed by the people they trust. The masses of them would change their minds immediately if they weren’t filled with total malarkey by their leadership and the media, which is almost totally owned and controlled by very wealthy “conservatives”. Don’t you smell the ruse? The people at the top, the ones who have orchestrated this issue , are neither liberal in the sense the average “left leaning” individual thinks or conservative in the way the average “right leaning” individual thinks. In fact those two groups, sans the misinformation, would think like honest Americans which both groups consider themselves to be. We agree on most things with slight differences in degree and which propaganda sources we believe. We are,however, intentionally fooled to believe we are enemies. The scam wouldn’t work without the divide and conquer technique used in many issues, not just this one.

Jim Papsdorf
July 8, 2009 12:05 pm

I know it is only “weather” but things are getting a little colder in the SH these days:
Deadly Cold Wave Brings Misery to Southern Peru
08 Jul 2009 14:31:00 GMT
An intense cold front has brought heavy snow, hail, strong winds and unusually low temperatures to southern Peru where the deaths of more than 150 children have been blamed on the cold. The situation prompted the Peruvian government to declare a state of emergency in 21 regions of the country, said the Adventist Development and Relief Agency (ADRA).
http://www.alertnet.org/thenews/fromthefield/219487/124706360614.htm

sylvain
July 8, 2009 12:17 pm

Now What, the MWP was limited to europe and the Inca empire but miraculously skipped the rest of the world.

Scott B
July 8, 2009 12:28 pm

On the bottom graph, how is the line around 9.2C the 20th Century average temperature when the majority of the 20th century is above the average? Also, the positive temperature anomalies appear to be greater than the negative.

Jakers
July 8, 2009 12:28 pm

The problem I have with this study is the time-line they have created. I’ve taken cores and worked up their stratigraphy, and taken C14 dates, and one has to be very careful about conclusions drawn from them. They don’t discuss how they determined the time periods much. “The chronology for the sequence was derived from six radiocarbon dates and seven 210Pb dates (Table 1).” OK – they got dates at AD280, AD630, and AD1360, and others outside that range, then they interpolated in between even though there was not a uniform deposition rate, to get 880, 1000, 1100, 1150, etc. In fact, looking at the site picture, deposition could easily have been pulsed from up slope erosion events.

Miles
July 8, 2009 12:33 pm

Seems Al Gore has more than the Third Reich to battle.

July 8, 2009 12:40 pm

Conservative&denialist (11:36:38) :
Thanks to Mr.Nasif Nahle (11:25:05) : we can guess that perhaps some
chemosmotic-anoxibiotic organisms are the ones after the “global warming” issue. 🙂

Heh! By the way, it should have said “oxygen”, not “oxigen”… Sorry. 🙂

KLA
July 8, 2009 12:40 pm

Well, limestone caves exist all over the world.
This study:
http://www.worldclimatereport.com/index.php/2006/11/15/stalagmite-story/
Shows a temperature record derived from isotopic data preserved in limestone stalagmites from such caves for Europe. It seems to me that all one has to do is to correlate similar data from caves all over the world to settle the question wether the MVP or roman warm period were local or global.

Jim L
July 8, 2009 12:41 pm

Frost warning for Eastern Canada. It’s July 8th for cryin’ out loud:
http://www.theweathernetwork.com/index.php?product=alerts&placecode=canf0253&region=wwcanl0027

Bruce Cobb
July 8, 2009 12:51 pm

Hmmm… The Medieval Maximum, a time of high solar activity occurred then. Must be just coincidence, though. Then again, C02 levels historically have followed temperature rises by approximately 800 years, which is about how long ago the MWP was. So, the fact that today, some 800 years after a significant warming we have a rise in C02 must be just another coincidence. Because, nothing beats the power of manmade C02! Sarc/off.

MikeN
July 8, 2009 12:57 pm

So did he establish that temperatures were warmer than now?
Jeff Id at The Air Vent has been working with Mann’s hockey stick algorithm, and he has shown how it could shrink a historic warming to be less than it really was.

Sam the Skeptic
July 8, 2009 1:11 pm

Nasif Nahle (11:25:05)
There is at least one warmist who is convinced of the toxicity of CO2.
I’ve lost the link unfortunately but his reply to someone who said that CO2 was not a pollutant was to suggest that he shut himself in a garage with has car engine running!
IF that’s the standard of science of the eco-fascists I think we probably have more to worry about than previously thought.

Jon Jewett
July 8, 2009 1:11 pm

This is Proof Positive that Halliburton and Dick Chaney have been plundering the Earth for oil longer than anyone has imagined!
I feel guilty ridiculing the AGWers. It’s like kicking a cripple.
Steamboat Jack

tty
July 8, 2009 1:13 pm

A minor quibble. Ollantaytambo is not near Machu Picchu. I know that Machu Picchu is more photogenic (though Ollantaytambo isn’t bad), but it is not really relevant in this context since it is at much lower altitude and has always had tropical climate, even during the LIA.

Conservative&denialist
July 8, 2009 1:21 pm

tty (13:13:16) : Ollantaytambo is not near Machu Picchu
You are right, but the authors are making a reference to Macchu Picchu as it is the most known icon of the Inca culture.

Philip_B
July 8, 2009 1:23 pm

On a related topic, the Roman Empire was based on agricultural trade. There is substantial archeological evidence that large areas of upland Britain were used for grain (wheat) production. These areas are currently too cold for any crop based agriculture despite development of more cold tolerant varieties.
It used to be generally accepted that Britain during the Roman era was several degrees warmer than currently. I recall reading in a book written in the 70s that Britain in the Roman era had the same climate as the south of France had currently.
It is also believed by some that the otherwise unexplained reason why the Romans left Britain was because a colder climate prevented crops growing and destroyed the agricultural economy. There is evidence that the human population of Britain collapsed around this time. A sobering thought for those who would have us believe a warmer world is bad.
Here is one of many texts on the subject.
http://books.google.com.au/books?id=spyCIqTzJu0C&pg=RA2-PA446&lpg=RA2-PA446&dq=roman+britain+grain&source=bl&ots=d8aalT8uQ2&sig=QDRI5TmwkuNggKkWnPjAal-ZGxY&hl=en&ei=IfpUSuLGD6ja6gPylejODw&sa=X&oi=book_result&ct=result&resnum=1
Note copyright material that prevents me cutting and pasting.

noaaprogrammer
July 8, 2009 1:30 pm

Edward: wrote: “There’s ample evidence of earlier warmer periods when people traversed Alpine mountain passes that are now covered by glaciers. The Romans did so as did the “Iceman” Otzi about 5300 years ago.”
If one believes the chroniclers of ancient Israel: Samson killed a lion, David killed a bear, (approx. 3,000 years ago.) If true, there had to be a totally different ecosystem in Palestine at that time in order to support a food chain for such large animals. Also, radar reveals dried river beds and ancient roads underneath the Sahara sand dunes.

Dave Wendt
July 8, 2009 1:36 pm

The ardent fervor the alarmists have invested in consigning the MWP and other past periods of warm climate to the memory hole derives from their realization that the entire edifice of their program of massive governmental intrusiveness and control rests on a foundational assumption that any warming that occurs will necessarily be catastrophic for humanity and the planetary environment. No information that suggests that a warmer climate may be on the whole beneficial can be allowed to freely circulate or their entire enterprise is in grave danger of collapsing like the house of cards that it is. Of course, even without the evidence of the benevolent nature of past warm periods, their presumption of catastrophic consequences is still largely unsupportable based the evidence provided by more current observations. That they willingly choose to disregard this is prima facie evidence that their fundamental concern is in driving the expansion of governmental control rather than in expanding environmental well being.

JimInIndy
July 8, 2009 1:36 pm

Edward (11:52:27)
Thanks for the Alpine/Otzi ref. I’ve seen several stories that link him to the tail-end of Bronze Age (or Minoan) Warming. He was killed on the run, fell against a snow-bank, was covered by a fresh fall, then wasn’t seen until summer melt in 1991. To me, this meant an extensive (non-SUV) glacial retreat 5000 years ago, and abrupt reversal. The BBC story reveals evidence of Bronze and Roman Warming, but also shows the lockstep thought of AGW true believers. Quoting:
— For Martin Grosjean( a climatologist at Berne University), the leather items found on the Schnidejoch, dated at over 5,000 years old, are proof, if any more were needed, that the Earth is now warming up. “The leather is the jewel among the finds,” he says. “If leather is exposed to the weather, to sun, wind and rain, it disintegrates almost immediately.
“The fact that we still find these 5,000-year-old pieces of leather tells us they were protected by the ice all this time, and that the glaciers have never been smaller than in the year 2003 and the years following.” –
The glacier was obviously smaller during the Bronze and Roman Warming, or the varied artifacts could not have been buried, and the probability, based on the evidence in front of Mr. Grosjean, is that the Bronze was warmer than Roman.
Those who do not believe in Earth’s natural climate cycles are the true deniers.

Steve Keohane
July 8, 2009 1:48 pm

Sam the Skeptic (10:00:17) From what I’ve read and heard from talks on the Anasazi cliffdwellers, drought was their demise, about the time of the LIA. They had trade routes into Central if not South America as they had feathers and stones from the far south. IIRC, they did not die in situ, rather, apparently moved on, though to parts unknown.

Purakanui
July 8, 2009 1:54 pm

KLA,
As I recall, stalactite analysis suggests a MWP in New Zealand and it was a time when the relatively recent Maori settlers flourished.
Incidentally, one of the authors of the study was Jim Salinger, recently dismissed from NIWA, our local Church of AGW.
I see Jim now has an affiliation with Victoria University, Wellington and is travelling the country (well, coming down to Dunedin a couple of times, at least). He is due to speak on ‘Ridding ourselves of our high carbon addiction’ or some such.
Cast out by the True Church, but still a devout Believer; there’s a soap opera episode there somewhere.

GoatGuy
July 8, 2009 2:03 pm

I think the attached is a keen screed (utilizing this here site’s citings) against the proverbial “mainstream thinking” that is expounded as science these days.
http://nextbigfuture.com/2009/07/various-ways-to-avoid-about-one-billion.html#comment-12332775
GoatGuy

D. King
July 8, 2009 2:07 pm

Boy, these guys better be careful; now they’re putting into
question the assertion that the evil Europeans killed off these
peaceful, human sacrificing, bloodthirsty, warmongering,
gentle indigenous people.

Ray
July 8, 2009 2:12 pm

More proof that the the poles are not melting…
NASA report of thinning arctic ice is deceiving
http://www.examiner.com/x-11224-Baltimore-Weather-Examiner~y2009m7d8-NASA-report-of-thinning-arctic-ice-is-deceiving

Jakers
July 8, 2009 2:13 pm

Steve Keohane (13:48:02) : Sam the Skeptic (10:00:17) From what I’ve read and heard from talks on the Anasazi cliffdwellers, drought was their demise, about the time of the LIA.
Actually, at the end of the 13th century, so in MWP.

Pompous Git
July 8, 2009 2:23 pm

From Polar Biology 2004
“Liguang Sun1, 2 Contact Information, Xiaodong Liu1, Xuebin Yin1, Renbin Zhu1, Zhouqing Xie1 and Yuhong Wang1
(1) Institute of Polar Environment, University of Science and Technology of China, Hefei, 230026 Anhui, P. R. China
(2) Institute of Earth Environment, Chinese Academy of Sciences, Xirsquoan, 710075 Shanxi, P. R. China
Received: 26 May 2003 Accepted: 12 February 2004 Published online: 24 April 2004
Abstract The historical seal populations at King George Island, Antarctica, for the past 1,500 years, have been estimated from the seal-hair abundance, bio-element concentrations, total organic carbon (TOC) and total nitrogen (TN) in one terrestrial sediment sequence influenced by seal excrement. Prior to human interference, the seal populations exhibited dramatic fluctuations with two peaks during 750–500 and 1400–1100 years before present (yr B.P.) and two troughs during 1100–750 and 500–200 yr B.P. A tentative comparison of the seal populations and historical climates in the Antarctic Peninsula region suggests that the seal populations may be linked to climate-related factors such as sea-ice coverage and atmospheric temperature.”

D. King
July 8, 2009 2:24 pm

evanmjones (09:20:12) :
fall of cliff dwellers
I can see how that would be a problem.
Tears Evan, tears!

Conservative&denialist
July 8, 2009 2:30 pm

Dear D. King (14:07:22) : Boy, these guys better be careful; now they’re putting into question the assertion that the evil Europeans killed off these
peaceful, human sacrificing, bloodthirsty, warmongering, gentle indigenous people.
The Inca culture was an advanced culture to which you owe most of the food you ate today.

George E. Smith
July 8, 2009 2:38 pm

Haven’t read any of the preceding yet; but I should offer this. Some years back, Dr “Willie” Wei-Hock Soon, and Dr Sallie Baliunas presented a paper, in which they examined a very large number of peer reviewed literature papers, from authors all over the globe, which related to studies that might show evidence of the MWP and/or the LIA.
They concluded that the evidence was clear that both MWP, and LIA were indeed GLOBAL PHENOMENA.
On the other hand, Michael Mann in his original “hockey stick” paper, as presented in the first IPCC report, clearly identifies the hockie stick as just a local anomaly; not a global phenomenon. I have here in my hot little hand; right out of my office desk draw; (for quick draw access), an actual portion (not a copy) of a Los Angeles Times Newspaper (impeccable source); page A12 from Friday, June 23 2006 on which can be found a reprint of the “hocky stick graph” claiming sources of the IPCC, and the National Academy of Sciences (impeccable sources); with a notation that references to colors in the chart have been removed from original; since the LAT section is printed in Black and white.
Not removed from the chart are the telling words; “NORTHERN HEMISPHERE” !!! ??? No not my caps; they are on the graph. So the LIA and MWP clearly were global in extent, but by Michael Mann’s own assertion, the hockey stick isn’t.
The interested researcher, can find that eventually, later copies of the chart were expurgated to remove the damning words; but too late to undo the damage that Mann did with this piece of science fiction. Incidently, the original data contains a noise level that is typically six times the amplitude of the “smoothed” faux data; which is quite typical of Gaussian Whie Noise signals; up to around 1600, and then mysteriously, the p-p noise level suddenly drops to about three times the smoothed false data, and around 1900, when the foot takes off into space, the noise level drops to around twice the smoothed output.
The chart bears only these other words: “Data from thermometers and from tree rings, corals, ice cores, and historical records.” The time frame is from 1000 AD to 2000AD, and the Y-axis says; “Departures in temperature (deg C) from the 1961 to 1990 average” I must confess that the “deg” is not a factual quote from the graph; which actually uses that little degree circle symbol which is not on my keyboard; so I admit to that editorial licence.
Just in case you wanted to know.
George
PS, I don’t recall whether the Soon/Baliunas review was a peer reviewed study, or whether it was something they posted on that Tech Central Station web site way back then. I’m sure you PhD Googlers can easily recover that paper of theirs.

George E. Smith
July 8, 2009 2:43 pm

“”” Purakanui (13:54:11) :
KLA,
As I recall, stalactite analysis suggests a MWP in New Zealand and it was a time when the relatively recent Maori settlers flourished.
Incidentally, one of the authors of the study was Jim Salinger, recently dismissed from NIWA, our local Church of AGW. “””
Tena koe, Purakanui ! I’m sure that Jim Salinger has an able ally in fellow Wellingtonian Vincent Gray; and for island balance, Chris de Freitas at the UofA (my alma mater), is a fellow traveller.
George

July 8, 2009 2:49 pm

get in on the climate funding as mentioned above. take a look at this from Australia. Details of grants awarded in the past five years under the ARC’s National Competitive Grants Program (NCGP) to projects
related to climate change. It is MINDBOGGLING! for teeny Australia.
http://sciencespeak.com/ClimateFunding.pdf
For climate history, check out Brian Fagan’s books.
The Little Ice Age 4.25 on http://www.amazon.com + ship – This one is better, and also covers the great warming somewhat. Also, Fagan does believe in CO2/Temp and states right away the party line. But then, in the book goes on all about the lack of sunspots in The Little Ice Age and some pretty interesting stuff about that.
The Great Warming

George E. Smith
July 8, 2009 2:54 pm

“”” noaaprogrammer (09:12:48) :
…and don’t forget the rise & fall of cliff dwellers in the Southwest – e.g. the Anastasi people. “””
These were the lost descendents of the lone survivor of the Russian Royal Family massacre; back around the Russian revolution era; They didn’t actually vanish; but later on became the East Germany Secret Police.

AlexB
July 8, 2009 2:55 pm

This is very serious. The threat of another Inca uprising in our time due to CO2 driven warming will cause havok. We might even approach a tipping point where the Inca empire is permanantly in control. I need to go do some modelling.

Tim Clark
July 8, 2009 2:57 pm

Barry Foster (11:45:16) :
Can someone guide me in the right directions? In this month’s BBC Focus magazine (here in the UK) they say that the Medieval Warm Period wasn’t global. But is the current warming global? Are there many places which show no warming, or even cooling since 1979? I know the lower troposphere shows no warming now, and neither does the Antarctic, but are there any other places? Thanks.

At the site below you can peruse graphical data from 1900-2008 for the United States. All seasonal graphs show a flat to negative trend. It’s an inconvenient truth.
http://www.ncdc.noaa.gov/img/climate/research/2008/us-final

Chris V.
July 8, 2009 2:58 pm

Any ideas why the MWP started around 800 AD in Europe, but didn’t reach South America until 300 years later (1100 AD)? Or why the MWP ended around 1300 AD in Europe, and at 1450+ AD in South America.
Curious.

July 8, 2009 3:02 pm

Barry Foster
I think Hawaii is one of those places that has not shown warning (and the States generally)
http://www.wrcc.dri.edu/cgi-bin/cliGCStT.pl?hi6198
A good book on past civilisations around the world who flourished in warmer times than today and fell when the climate cooled is called ‘Earth in the Balance’ published in 1992. The examples were being used to demonstrate what could happen if we much up our climate (rather than let nature take its course).
The author of this very well researched book? Al Gore. Too bad he didn’t get too speak to Michael Mann before they both went mad
Tonyb

Jim
July 8, 2009 3:11 pm

Ummmm … ahhhhhh …. Ah! Yeah, that’s it! The MPW was ONLY IN THE NORTHERN HEMISPHERE!!

July 8, 2009 3:13 pm
Ray
July 8, 2009 3:19 pm

How much disinformation the people at the UN need to spit out in order to get more of our money? If Global Warming always made Empires rise because it enhanced agriculture to feed the people and the armies, why would it be different today?
UN Official Seeks G-8 Cash for Climate Change Fund
Top UN climate official to AP: G-8 should help poor countries now with global warming: http://abcnews.go.com/International/wireStory?id=8008662

D. King
July 8, 2009 3:35 pm

Conservative&denialist (14:30:59) :
The Inca culture was an advanced culture
Agreed.
to which you owe most of the food you ate today.
Please explain.

George E. Smith
July 8, 2009 3:58 pm

I hate to go OT Charles; but the above is on continuous play now, and this does seem an appropriate place to put this; I hope you’ll forgive me.
George
So from the 15 May 2009 issue of SCIENCE (is this a peer reviewed Journa ?); on page 888, under the heading “Ocean Science”.
“Ice Sheet Stability and Sea Level.” by Erik R. Ivins. A reference #19 for which there is no precedent says; “This work was performed at the Jet Propulsion Laboratory, California Institute of Technology- (which is well known to be on Colorado Blvd in Pasadena CA; and not in Antarctica.)-and funded by the Solid Earth and Surface Process Focus Area within NASA’s Earth Science Program.”
I need to quote some verbatima; but not too much. My EMPHASES will be additive.
“How much will sea levels rise IF the West Antarctic Ice Sheet becomes unstable.”
“Volume changes in the Antarctic Ice Sheet are poorly understood, despite the importance of the ice sheet to sea-level and climate variability. Over both millenial and shorter times scales, net water influx to the ice sheet (mainly snow accumulation) NEARLY BALANCES water loss through ice calving and basal ice shelf melting at the ice sheet margins (1). However there MAY BE TIMES when parts of the West Antarctic Ice Sheet (WAIS) are lost to the oceans thus raising sea levels. ”
Well that is the very beginning of the paper, and I need cite no more, because it continues in a like mode.
Notice the work was done in sunny Southern California, and not in Antarctica. One may infer that not a jot of measured observation data is included in this paper which is fullof IF, or MAYBE, and similar jargon of SCIENCE FICTION; rather than experimental observation of normal research science.
There’s not a jot of science in this paper; it is 100% Science Fiction; what MIGHT happen IF this DID happen. About once full page paper with 18 reference numbers, of which I only copied #(1); which just happens to refer to an eartlier SCIENCE paper.
You can bet on the mainstream media if they stumble across this drivel; will cite a model study, as actual observational science; instead of the completely made up WHAT IF scenario of a science fiction “Star Trek” episode.
This is just an example of wht is printed in SCIENCE in lieu of science.
On another web site today, I learned that some Aussie bloke (oceanographer)says the whole Great Barrier Reef will be gone in 20 years. I say good riddance to that graveyard of ships; I’m sure I won’t be here to see it off, but maybe My sons can go and fish for some wonderful new species, when all that bric-a-brac is outa there.
So we have studies of what will happen IF the entire gret barrier reef disappears in 20 years; or what will happen IF the whole West Antarctic Ice Sheet (WAIS) suddenly falls in the southern ocean.
I haven’t yet seen a paper on what will happen IF the Moon falls into the Pacific Ocean; but you can bet that some taxpayer funded research grant has some fool woking on such a paper.
Frankly I’m getting tired of “Studies” (done in the local bars) on WHAT MIGHT HAPPEN IF some as yet never before observed SCIENCE FICTION SCRIPT should happen to get played out.
As a taxpayer, I don’t actually begrudge paying for scientists to actually do experimental science to observe something; or for theoretical scientisst to devise plausible theories for some phenomenon that someone else actually did observe.
But I am tired of paying for ersatz “scientists” to write SCIENCE FICTION for Hollywood film makers to consider for release to a GULLIBLE PUBLIC.
As a paid up AAAS reader of SCIENCE; I now have an alarm bell that goes off , everytime i come across one of these movie scripts masquerading as actual science.
You guys need to get a life, and you should be ashamed of yourselves for this charade.
George
Thank you Charles for considering this OT (on topic)
Reply: It is funny that on topic and off topic have the same acronym. A source of endless confusion for moderators and the potential conflagrations, both flammable and inflammable, which may ensue. ~ charles the moderator

KLA
July 8, 2009 3:59 pm

Come on people. You just don’t get it.
It is really well known that the MWP was only a local phenomenon. It was local in Europe, Asia, Australia, South America, North America and Africa.
It was a local phenomenon in those places ONLY.
Kind of like Steve Martin in “Pink Panther”, when he tells a suspect to stay in the local vincinity:
“Do NOT leave Europe, Asia or the Americas”.

George E. Smith
July 8, 2009 4:17 pm

Some subtleties of the above SCIENCE paper; and that cited piece is actually the opening paragraph or part of it, with nothing removed in betweeen.
Did you catch that disclaimer about the snow pileup NEARLY BALANCING the ice calving over short and millenial time scales; in otherwords pretty much always so far as we know. See how cleverly they don’t say which way that nearly balance tips. Izzere more snow pileup than calving; or verse vicea.
They use the form that leads you by the nose to conclude that it is out of whack since it is only NEARLY balanced; and that the whack is in favor of the calving outdoing the snow pileup.
Clearly over the millenia, the darn balance is pretty fine, because if it tipped too far one way; there would be ice all over El Camino Real in silicon Valley; while if it tipped too far the other way, the Hudson River would be halfway up the Empire State Building.
Anybody want to wager that there is some feedback mechanism involved; Le Chatalier’s Principle in action or some facsimile thereof.
Too much ice calving, and losss of sea ice from the Antarctic perimeter, exposes a heap of new open sea surface; which is somewhat hotter than the ice; whcih would promote a massive increase in oceanic evaporation, and an increasing deposit of snow on top of that sheet ice that always seems to be in delicate balance with the snow, and that increased mass accelerates the march to the sea to stop the pileup getting too large.
Too much sea ice, and growing ice shelves, and the ocean evaporation slows down depriving the southern continent of its snow resupply, so the warmer ocean can work on melting some of that excess ice perimeter ice.
Yeah I plan to hang around to see what happens when the Moon crashes into the Pacific Ocean.
George

Michael Hauber
July 8, 2009 4:52 pm

The Man 98 ‘Hockey Stick’ (as illustrated) showed a drop in temperature from the medieval warm period to the little ice age of 0.3 degree.
The ‘skeptic approved’ Loehle reconstruction and the graph shown here show a drop of about 1.2 degrees.
The revised Mann 08 reconstruction now shows a drop of about 0.8 degrees. The difference is 0.4 degrees.
One of the big factors in the ‘hockey stickness’ of the Mann 08 reconstruction and the lack of ‘hockey sitckness’ of the Loehle reconstruction appears to be how the modern record period is treated. To get a hockey stick Mann 08 creates a reconstruction for the northern hemisphere only. The modern temperature trend for the northern hemisphere shows a steeper increase than for the whole globe.
In contrast Loehle creates a global temperature series, and with a slightly stronger medieval warm period, and a less steep modern global increase (less steep than NH increase), arrives at more of a U shape, with the modern increase a little lower than the medieval period, but not enough to be sure the difference is significant.
In contrast the ‘non hockey stick’ version of the temperature record posted above shows an increase of only about 0.2 degrees since 1900. My guess is that the temperature record ends around 1980 so loses another 0.4 degree or so increase between 1980 and today.

Highlander
July 8, 2009 5:01 pm

As I’ve stated priorly, and here again: If CO2 was supposed to be any kind ‘warming agent,’ then I must enquire as to how it was that during the warming spell of the MWP —when MORE people were born and thence MORE CO2 was released in that period of time as a result of more carbonaceous materials (dung, wood, peat and coal) being used by more people, very much less efficiently than now— that with all the carbon in the atmosphere, the Earth suddenly got colder at the end of said MWP?
.
Further, with the advent of the Little Ice Age, how was it —again with INCREASED use of said carbonaceous materials because of the ensuing cold— that releasing yet MORE CO2 into the atmosphere caused the climate to become EVEN COLDER?
.
If CO2 is supposed to be some kind of ‘warming gas,’ then someone PLEASE explain how it was that releasing more of it caused the Earth’s climate to get colder?
.
I await a ‘learned’ reply which to date has NOT been forthcoming.
.
I am patient. How long must I wait?
.

July 8, 2009 5:24 pm

Chris V. (14:58:13) :
Any ideas why the MWP started around 800 AD in Europe, but didn’t reach South America until 300 years later (1100 AD)? Or why the MWP ended around 1300 AD in Europe, and at 1450+ AD in South America. Curious.
Smaller continental surface and thicker ice cap in the Southern Hemisphere. That’s the possible explanation.

SteveSadlov
July 8, 2009 7:08 pm

RE: Philip_B (13:23:45) :
I believe significant population collapse is imminent, the worst ever. We are seriously overextended in our reliance on marginal growing regions both at high and low latitudes. High latitudes of course will succumb rapidly the moment the full crash from the Twentieth Century Warm Period sets in – we may well be experiencing warning waves of this presently. The double whammy comes from the knock on effect in the higher latitudes of the tropics (e.g. 15 – 25 deg – SE US, Southern / SE Asia, etc) as the Monsoonal moisture flows of summer and early fall fail due to colder temps in continental interiors. That of course will bring mega droughts to the impacted regions. Imagine the effect of a mega drought in South and SE Asia.

July 8, 2009 7:10 pm

“Any ideas why the MWP started around 800 AD in Europe, but didn’t reach South America until 300 years later (1100 AD)? Or why the MWP ended around 1300 AD in Europe, and at 1450+ AD in South America.”
The answer lies in the huge thermal inertia of both Oceans surrounding South America, acting as a buffer to both the warmth and the cold.
However, the cold must have fallen quite fast in the central or ‘mediterranean’ part of the continent, away from the buffering effect of oceans, as the Spanish chroniclers state that at the time of Santa Cruz de la Sierra’s (Bolivia) foundation in 1591, they describe terrible frosts that split in half huge tree trunks. It is possible because those 200-year-old trees grew during the previous much warmer period. Santa Cruz is at about 32ºW and 15ºS coordinates, in the border of the Amazon jungle, hot tropical climate.

July 8, 2009 7:10 pm

The MWP is a unique period in the last few thousand years. Normally the Sun has a slowdown of activity every 172 years (roughly), during the MWP it missed a beat causing a longer period of good solar activity, like we have experienced over the last 200 years but lasting longer.
The length of the MWP in this report differs from northern hemisphere records by about 300 years, did the Wolf & Sporer minima have no effect in the southern hemisphere?

Philip_B
July 8, 2009 7:30 pm

Any ideas why the MWP started around 800 AD in Europe, but didn’t reach South America until 300 years later (1100 AD)? Or why the MWP ended around 1300 AD in Europe, and at 1450+ AD in South America.
See Craig Loehle’s multi proxy reconstruction (link below and download the pdf).
It shows the MWP lasting from 650 AD to 1450 AD (approx) with a significantly warmer and shorter period from 800 AD to 1000 AD. Both are referred to as the MWP.
The graph above showing a steady warming then cooling in the MWP is an over-simplification. Loehle’s reconstruction shows multiple warming peaks with cooling in between, before a steep temperature fall into the LIA around 1500 AD.
http://www.ncasi.org/publications/Detail.aspx?id=3025

Philip_B
July 8, 2009 7:58 pm

SteveSadlov,
I genuinely worry about the effect of a major volcanic eruption producing another Year Without A Summer or worse. Millions died even though at the time people kept food supplies for 12 months.
In our Just In Time world the effect would be awful. The YWAS happened less than 200 years ago and we know for certain it will happen again and without warning. It could happen tomorow and no government anywhere is remotely prepared.
Yet they are spending prodigous resources on AGW, a problem that may not even be real and even if it is, we have decades to prepare for.

July 8, 2009 8:43 pm

Philip_B (19:30:39) :
See Craig Loehle’s multi proxy reconstruction (link below and download the pdf).
Indeed, Craig Loehle’s multiproxy reconstruction on the variability of temperature during the last 2000 years is the most reliable source on this issue. I have used his database in some comparisons of temperature, solar irradiance and carbon dioxide concentration. Loehle’s database comprehends the period from 16 AD to 1980 AD; however it can be easily complemented with UAH/AMSU2 database.

papertiger
July 8, 2009 9:09 pm

The length of the MWP in this report differs from northern hemisphere records by about 300 years, did the Wolf & Sporer minima have no effect in the southern hemisphere?
I can think of a reason. The water. The South is dominated by ocean which is a lot slower to heat up and cool down.
You know for the purposes of finding a climate signal it would be smart to treat the two halves as separate entities. Like take all the climate stations from south of the equator and average that, draw your graphic. Do the same with the north. So instead of the one world graph, present two.
The South should be the last to warm up, the North the first to cool off.

SteveSadlov
July 8, 2009 9:19 pm

RE: Philip_B (19:58:41) :
RE: “It could happen tomorow and no government anywhere is remotely prepared”
Here is the quantity of faith I currently have in governments and main stream culture, to understand risks and develop appropriate contingency plans: .
Careful, if you blink you might not see the full stop I typed there …
This statement applies not only to sudden climate change, a well known issue, but also, to other mega disasters and things like severe geopolitical, global scale miltary and economic matters.

July 8, 2009 11:03 pm

papertiger (21:09:28) :
I can think of a reason. The water. The South is dominated by ocean which is a lot slower to heat up and cool down.
You cant have your cake and eat it too.

E.M.Smith
Editor
July 9, 2009 12:27 am

Conservative&denialist (14:30:59) : The Inca culture was an advanced culture to which you owe most of the food you ate today.
Wow! They invented tea, milk, sugar, eggs, pancakes and wheat, berry syrup, ravioli (beef), whole wheat bread, butter, pink lemonade, beets (pickled), chicken, penne pasta, alfredo sauce, sauted vegetables with italian seasoning, olives, olive oil, coffee and cheese? Who knew! 😎
BTW, I did have tomato sauce on the ravioli and there was some yellow crook neck squash in with the onions and and a couple of tomatoes in the sauteed vegetables. And I do know that we owe a great deal to corn aka maize and common beans… but there was food pre-inca contact and I still eat lots of it… Peas, fava beans, lentils, soy, garbanzos, mung, adzuki … not all beans are from America, not even most beans.. Wheat, barley, oats, spelt, rice, rye, triticale, buckwheat: there were plenty of grains before corn/maize. Squash / pumpkin are nice, but so are radishes, turnips, kale, sweet potatoes and cabbage. Potatoes are a nice starchy root, but there are lots of nice starchy roots (Parsnips are one of my favorite, as are yams or sweet potatoes) and while marinara is a nice sauce, so is Pesto…
We could happily live without the bounty of new vegetables that came from the Americas. It is better with them, but not in any “bow down and say a prayer of thanks” way.
FWIW, I’m allergic to corn. Not dramatically, just enough that I have to avoid it. I’ve done just fine putting millet flour into “corn bread” recipes and sorghum does a fine job substituting in other contexts. Common beans are nice, but I’ve made a dandy lentil chili and even mung bean chili. Green beans are nice, but so are “yard long beans” and snow peas.
My point?
Substitution.
We can substitute a large number of food species for each other. The land would still be there growing a crop if corn (maize) were gone tomorrow. (In Texas, the alternate crop when the rain is expected to be a bit light is Sorghum. In Africa it tends to be millet.) Potatoes are a good cool season crop, but so are many other starchy foods such as short stem grains, winter wheat, beets, turnips, parsnips, root parsely, salsify, … We grow something because it is a little cheaper to grow or a little better flavor, or sometimes it’s just a bit more familiar (and sometimes because it is different); not because there is no alternative.
So yes, be thankful for all the variety of plants we can use, but realize that we’d be fine if we’d never seen an American species…

E.M.Smith
Editor
July 9, 2009 1:20 am

Philip_B (19:58:41) : I genuinely worry about the effect of a major volcanic eruption producing another Year Without A Summer or worse. Millions died even though at the time people kept food supplies for 12 months.
And well you ought… Chaiten is still blowing in Chili and the ring of fire is edging to an active state. There is a historical correlation of more vulcanism with low sunspots (ie. it may not be accidental that you get a big volcano right in the middle of the low solar activity periods “confusing” causality…)
The quake storm around Chaiten showed the magma pool to be very very large. Folks are just hoping it does not blow as a supervolcano and they are hoping that it stops venting and the magma pool cools all on it’s own… “Hope is not a strategy”…
In our Just In Time world the effect would be awful. The YWAS happened less than 200 years ago and we know for certain it will happen again and without warning. It could happen tomorow and no government anywhere is remotely prepared.
I have some comments about that here:
http://chiefio.wordpress.com/2009/04/06/food-storage-systems/
We know for certain that it will happen again. We just don’t know if it will be caused by a volcano, a rock fall from space, or some other cause; or exactly when.
During the 1800’s folks commonly stored the produce from one whole year for use in the following year. We now ship grains world wide, producing and consuming with as little storage as possible. A couple of months at most. Very silly. One big rock from space into the ocean and the shipping is sunk. It would take several years to rebuild enough ships; for example.
All you need to do is buy 8% more food each month of what you normally would eat (in storable forms, like dried fruit and canned goods) and you will have a “one year storage system” in about one year… It takes about 1 “dry pound” to feed a person for a year. 365 lbs of food is not very much space. About the size of a large filing cabinet or small desk. You will save more money by reduced prices buying in bulk and avoiding trips to the store than it costs to make happen. All it takes is the desire to do it.
We are in the early stages of a crop failure in wheat right now in Argentina and Canada. It’s not going to be better any time soon. We have drought lining up in the “dust bowl” (hmmm… and that was about 80 years ago… when the sun was quiet… ) parts of Texas and Oklahoma. California has shut off water to a large chunk of crop land and rainfall is low. It’s mostly about the water, and trends this year are “not good”.
So I’m encouraging my friends to start a food storage system and make sure they are prepared for “bad times”; even if those bad times are just a lost job or an earthquake or hurricane…
(While I don’t recommend it – since folks tend not to actually eat the stuff – you could make a ‘dirt cheap’ food storage system out of a couple of 50 lb sacks of beans and rice along with some vitamin pills. It’s about $300 for 300 lbs of such foods even bought at places other than the bulk sellers. I think it is better to buy what you already eat, since then you WILL eat it and not waste it… but if things go “bump in the night”, well, $100 at Costco or WalMart buys a lot of beans & rice in a hurry…)
You don’t need to depend on your politicians and government weenies to do the right thing, you can just go do it yourself a lot cheaper…

Philip_B
July 9, 2009 2:20 am

SteveSadlov,
I get my history from first person accounts by people who were there at the time.
I recall a particularly harrowing account from a young Finnish girl who described roads choked with starving people searching desperately for food and lined with the dead and dying (in the winter after the Year Without a Summer).
It may not be like that in America or Australia, but the Indian sub-continent and China are an entirely different matter.
FWIW I think the likeliest use of nuclear weapons is blackmail of food haves by food havenots after a repeat of the Year Without a Summer.

dennis ward
July 9, 2009 2:46 am

Highlander
/// As I’ve stated priorly, and here again: If CO2 was supposed to be any kind ‘warming agent,’ then I must enquire as to how it was that during the warming spell of the MWP —when MORE people were born and thence MORE CO2 was released in that period of time as a result of more carbonaceous materials (dung, wood, peat and coal) being used by more people, very much less efficiently than now— that with all the carbon in the atmosphere, the Earth suddenly got colder at the end of said MWP? ///
Possibly for the very same reason that volcanoes that emit CO2 also cause temporary cooling if they also spew out sulphur, ash and other materials that blot out the sun.
And possibly because greenhouse gases are only one factor that affect climate.
And possibly because the number of people alive back then were insignificant compared to the 6 billion alive today.

July 9, 2009 3:51 am

Jakers (14:13:53), Steve Keohane (13:48:02), Sam the Skeptic (10:00:17)
Rather than drought, what may have over-stressed the Anasazi culture was a change from a weather pattern with regular, moderate rains to a pattern with deluges and heavy thunderstorms.
The first pattern allowed the construction of irrigation systems which scooped waters from streams and ran them in canals along the sides of canyons to terraces with corn fields. The shift to heavier rains not only knocked down the small dams, but eroded the stream beds to a lower level, which made the former canals out-of-reach of water-diversion-projects on a small scale.
When I lived in that area I watched a stream bed hold little more than a trickle of snow-melt for over two years. During that time a sand dune was slowly building across the stream bed, which was about fifty feet wide and eight feet below the flood plain. Then, in a single big thunderstorm, the entire stream bed was filled to the brim with swirling red water, with entire cottonwood trees charging by in the surge. Two hours later the water was gone. So was the sand dune.
Imagine building any sort of small-scale irrigation system under such conditions! It’s basically impossible. However the Anasazi managed to feed a large population. They were so numerous that (in the 1980’s) the local people often hushed up the discovery of a dump of broken Anasazi pottery shards. Those shards were everywhere, and officially you were suppose to stop all construction and wait for an archeologist to come and investigate. Local folk often didn’t want to be bothered, (especially for small stuff that held no promise of attracting tourists,) so often the law was ignored.
Much about the Anasazi culture is mysterious and fascinating. For example, each pueblo may have spoken a different language. I think research money ought be taken from Hansen and Mann and either sent to people studying the Anasazi, or to me. ( I’d figure out something to study, if I had the money and time.)

JP
July 9, 2009 5:10 am

If memory serves me correctly, the ebb and flow of the Franz Josef glacier in New Zealand coincides with the ebb and flow and several Swiss glaciers. That is, the rapid expansion of the New Zealand glaciers coincided with European glacier advancement during the coldest periods of the LIA. Ditto for thier retreat.
While precipitation patterns also play a major role in glacier advancement or contraction, it is coincidental that glaciers located on opposite locations on the globe and in different hemispheres would grow and contract at the same time. I think this points to a synchronous period of cooling and warming in both hemispheres.
In the tropics and subtropics, changes in precipitation patterns are probably a more accurate metric for following the global temperature signal in lieu of any better proxy. Dr. Brian Fagan has done a great job in outlining this idea.

Editor
July 9, 2009 5:39 am

Sorta OT (Off) relative the headline, sorta OT (On) relative a timeline.
After a flurry of articles centered aroung 6,000 years ago, I put together Glacial Retreat of 5,000-7,000 Years Ago. It’s a pretty broad time period, but includes accounts from Otzi in the Alps to newly exposed ancient forests in Peru:
Glacier melts are erasing climate record
“The largest glacial ice cap in the tropics, Quelccaya, lies in Peru. As it’s been retreating, it occasionally uncovers surprises that had been buried as the glacier grew. Melting recently uncovered one wetland region that had been buried under ice for more than 5,000 years, revealing some 50 different members of the botanical community that once thrived there.”
—–
Ric Locke (09:30:13) :
Another Ric? Anecdotal evidence of the large readership here. There’s
another Werme here too, but he’s my brother, so the relationship there
is questionable. Err, unquestionable. Umm, whatever.

Don S.
July 9, 2009 7:37 am

Actually the Anastasi fell off the cliff and landed in Russia where they became the Royal Family. The last survivor of this family, Anastasia, having never relinquished her claim to the Russian throne, died in 1984. Unfortunately, pesky DNA tests have proved that the woman who died in 1984 was not related to the Romanovs. Here endeth the tale.

Tim Clark
July 9, 2009 7:40 am

E.M.Smith (00:27:49) :
Potatoes are a nice starchy root, but there are lots of nice starchy roots (Parsnips are one of my favorite, as are yams or sweet potatoes).

In my time on this blog, this is the first time I must disagree with you. We both were raised frugally, and our family(s) survived on every imaginable garden produce, fresh and canned. One of my favorites was kohlrabi. But parsnips, yams, and sweet potatoes?
I’d rather die.

Nelson
July 9, 2009 9:46 am

Like the MWP, the Inca Empire and Machu Picchu never happened.
Seriously, I also would like to know how our brighter minds on this site reconcile the difference in timeline given for the “European” MWP and the SH MWP (if that is an appropriate way to distinguish) as implied by the subject paper.
The references on Wiki re: MWP cite a 1979 paper (presumably untainted by a zeal for AGW-targeted grant funding) that says a stalagmite in New Zealand indicated a MWP of 1050-1400. This seems to correspond more closely to the warm period that caused the Incas, also in SH, to flourish although it ends 100+ years earlier.
Does this imply that there were warm periods in both hemispheres but that regionally these phenomena were far from simultaneous? Would this in turn imply that something other than well-mixed GHG (or even sunspots), which presumably would impact global temps more uniformly, is the primary driver?
To my little pea-brain, it would seem that oceans are the regulators and have the capacity to regulate on a short-term (El Nino/La Nina) as well as longer-term MWP/LIA basis. But don’t they have to get the heat they absorb/release from somewhere…?

July 9, 2009 12:47 pm

Tim Clark said
“But parsnips, yams, and sweet potatoes?
I’d rather die.”
Have you ever had young parsnips roasted to a golden brown. Better than roast potatoes- Truly delicious. Sweet potatoes are great in Curries.
tonyb

Ray
July 9, 2009 12:51 pm

I think I know why great civilizations collapse one it get cold…
People stay indoors and don’t socialise anymore. All the bonds in society break down and nobody cares anymore. I see that every winter.

Mr Lynn
July 9, 2009 5:49 pm

Ray (12:51:22) :
I think I know why great civilizations collapse one it get cold… [sic]
People stay indoors and don’t socialise anymore. All the bonds in society break down and nobody cares anymore. I see that every winter.

Actually, I have heard it claimed that the genius that informed the American and industrial revolutions, and the intellectual fervor that accompanied them, were a result of the cold weather in places like Boston keeping one’s mind on indoor studies, as opposed to the torpid South, where people lay around on their porches languidly sipping mint juleps and visiting.
That, of course, is a conceit one hears in places like Harvard.
/Mr Lynn

July 9, 2009 6:04 pm

Let`s not forget the Mississippian culture centered around Cahokia which flourished between 900 and 1600; there is evidence that the great city collapsed do to food shortages. By the time Columbus arrived in America Cahokia was seriously deteriorating-and the mound builder culture withered after that, by the early 1500`s this empire was largely kaput.
Now let me see; what was happening in Europe around this time? Gee, I wonder if there was any connection between warm weather in Europe and a large civilization flourishing in North America?
How about those Mongols, too; Temujin was declared Great Ruler (Genghis Khan) in 1206, but of course this nomadic tribe had been growing in power for a number of years. After Genghis Khan lead the explosion out of the Gobi (a place traditionally limited in food supply because it`s a desert) his band of horseback nomads conquered much of the civilized world and ruled an empire far larger than that of Julius Caesar`s for over a century. Now, why did a bunch of ignorant horsemen living in the desert suddenly unite and invade all of the surrounding country?
The Maori first discovered New Zealand around 950 and the “great fleet” of settlers came sometime during the 11th century. Why was that? What was it driving thousand of people to risk their lives in canoes to resettle at this particular time?
We could go on and on with this.

George E. Smith
July 9, 2009 6:47 pm

“”” Timothy Birdnow (18:04:36) :
The Maori first discovered New Zealand around 950 and the “great fleet” of settlers came sometime during the 11th century. Why was that? What was it driving thousand of people to risk their lives in canoes to resettle at this particular time? “””
They probably heard that there were 20 sheep for every person in New Zealand, and that they made some pretty good wines; the Kiwis that is; not the sheep.
Supposedly Kupe discovered the place around 960 AD, but the actual migrations were spread out over several hundred years. They talk about the seven great canoes; but there were a bunch more than that; I can only remember the Arawa, and the Tainui; maybe there was a Takitimu, or is it Takitumu ?
Maori is a very simple language; only 14 letters; plus that impossible ng sound, and every syllable ends in a vowel; so there are no esses to make plurals, so singular and plural are the same. The vowel sounds are absolutely identical to Spanish; I happen to have a resident Spanish expert, and she says Maori is identical in vowel sounds.
To bad they killed off all the Moa; I could use a 12 foot pet bird to kick some A***.
George

SteveSadlov
July 9, 2009 7:57 pm

RE: George E. Smith (18:47:00) :
Kiwi wit at its finest. 🙂

JIm Clarke
July 9, 2009 8:32 pm

I always love it when the AGW types proclaim that the LIA and the MWP were not global. The funny thing is that there is more evidence in the paleo record that these episodes where global than exists for the current warm period.
Current global warming is almost exclusively in the high northern latitudes, more localized than the MWP.

Phil.
July 9, 2009 9:04 pm

Sam the Skeptic (13:11:06) :
Nasif Nahle (11:25:05)
There is at least one warmist who is convinced of the toxicity of CO2.
I’ve lost the link unfortunately but his reply to someone who said that CO2 was not a pollutant was to suggest that he shut himself in a garage with has car engine running!
IF that’s the standard of science of the eco-fascists I think we probably have more to worry about than previously thought.

You have a problem with that?

REPLY: I sure do Phil. I find it abhorrent that you think such comments are OK. Explain yourself – Anthony

[REPLY – Then perhaps explain the difference between carbon monoxide and carbon dioxide . . . ~ Evan]

July 10, 2009 5:01 am

Thanks, George! I`d love such an a-kicking bird myself. Can`t blame `em for coming for the Sauvignon Blanc, btw.

Dave Wendt
July 10, 2009 10:06 am

Phil. (21:04:39) :
Sam the Skeptic (13:11:06) :
Nasif Nahle (11:25:05)
There is at least one warmist who is convinced of the toxicity of CO2.
I’ve lost the link unfortunately but his reply to someone who said that CO2 was not a pollutant was to suggest that he shut himself in a garage with has car engine running!
IF that’s the standard of science of the eco-fascists I think we probably have more to worry about than previously thought.
You have a problem with that?
REPLY: I sure do Phil. I find it abhorrent that you think such comments are OK. Explain yourself – Anthony
[REPLY – Then perhaps explain the difference between carbon monoxide and carbon dioxide . . . ~ Evan]
Way to stay classy Phil.
But the commenter that Nasif mentioned wasn’t as off base as you other guys assumed. With the improvements in auto exhaust standards carbon monoxide is unlikely the to be the lethal agent in modern suicide by asphyxiation by automotive exhaust and CO2 probably plays more of a part than CO although the actual smoking gun is probably O2 depletion. http://journals.lww.com/amjforensicmedicine/Abstract/2002/06000/Asphyxial_Deaths_Caused_by_Automobile_Exhaust.2.aspx

July 10, 2009 1:09 pm

Dave Wendt (10:06:02) :
Way to stay classy Phil.
But the commenter that Nasif mentioned wasn’t as off base as you other guys assumed. With the improvements in auto exhaust standards carbon monoxide is unlikely the to be the lethal agent in modern suicide by asphyxiation by automotive exhaust and CO2 probably plays more of a part than CO although the actual smoking gun is probably O2 depletion. http://journals.lww.com/amjforensicmedicine/Abstract/2002/06000/Asphyxial_Deaths_Caused_by_Automobile_Exhaust.2.aspx

Correction: it was not me who made the commentary but Sam the Skeptic.
Nonetheless, I stand on Sam the Skeptic’s, Anthony’s and Evan’s assertions because if the authors at AM Journal of Forensic Medicine attribute the deaths to high concentrations of carbon dioxide and depletion of oxygen they would be talking about asphyxiation, not intoxication, and the carbon dioxide remains as a non-hazardous product. The same happens with liquid water and water vapor; water, sand, carbon dioxide and other non toxic products suffocate, do not intoxicate.
Some Wikipedia authors have forced the definition and classification of toxic substances for making carbon dioxide and water appear as toxic substances. However, they do not change the chemistry of the body neither set off apoptosis nor stop or transmute metabolic processes, as toxic substances do; they simply asphyxiate, that is, do not permit the oxygen to act as an acceptor of electrons. It is a 101-biophysics matter.
Hyponantremia, a condition of high dilution of sodium in biological tissues for taking too much water, is not a result of toxicity of water, but an osmotic misbalance. The terminology has been corrupted at the extreme. You are toxic, I am toxic, air is toxic, water is toxic, pinto beans are toxic, and the whole Universe is toxic… This is stupid. As I have mentioned above these lines, the real and original concept of toxicity is about substances which change the chemistry of the body, induces apoptosis, and stop or alter the metabolic processes.

Dave Wendt
July 10, 2009 3:16 pm

Nasif Nahle (13:09:58) :
Sorry for the misattribution, I agree with the rest of your comment about the nontoxicity of CO2 entirely and had planned to add something very similar to my own comment, but I had to go take care of a problem, so I just posted what I had finished. I had also intended to add something to the effect, that if we took a tiny fraction of the money they’re about to squander trying to suppress carbon and invested it in subsidizing the transfer of well developed American technologies for cleaning non CO2 pollutants from smokestacks and autos to developing countries like China and India, we would see real and profound improvements in not only the world environment, but the American economy as well. Of course, improving the American economy seems to be exactly opposite to the goals our politicians are striving to achieve.

bill
July 11, 2009 8:52 am

Comparing the above unreferenced graph
http://wattsupwiththat.files.wordpress.com/2009/07/mwp-hockey-warming_graph.gif
to the now read the referenced document
http://www.clim-past-discuss.net/5/771/2009/cpd-5-771-2009.pdf
One concludes that they do not refer to the same climate:

Intro:A multi-proxy, high-resolution 1200-year lake sediment record was analysed at Marcacocha, 12 km north of Ollantaytambo, in the heartland of the Inca Empire. This record reveals a period of sustained aridity that began from AD 880, 10 followed by increased warming from AD 1100 that lasted beyond the arrival of the Spanish in AD 1532.
5.4 AD 1400–1540
This interval, which coincides with a period of rapid Inca expansion outside of the Cuzco heartland, appears to have been relatively stable from a climatic point of view.
Temperatures seemed to have remained warm, with precipitation (and corresponding lake-levels) being low. Despite this climatic stability, significant land-use changes occurred in the basin.

Whereas the graph shows no such stability in MWP warmth in fact it dives into minus 0.5C

Ray T
July 13, 2009 6:23 pm

George E. Smith (14:38:02) : You can make the degree sign (and most other characters) by using the Alt-key & your numeric keypad to type the ASCII equivalent. E.g., “£,” “º,” “½,” “α,” “Ω,””√,” “♣,” “♫,”☺” are all possible.
BTW, “º” is Alt-167. Hold down the Alt key and type the number, then let go!