This is another post from Hank. This post ties a paleo study with recent periods in civilization and very brief synopsis of a few cultures. There are many things which go unstated in this post. Hank assures me he’s prepared for the questions.
Guest Post by Hank Hancock
I have a fascination with anthropology and history. One of my good friends is an archeologist. We’ve explored and photographed ancient settlements together and talked about evidence for climate shifts having an effect upon civilizations. He is adamant in his knowledge that there is overwhelming evidence for it in the archeological record. I share his views.
In 2009, Dr. Fredrik C. Ljungqvist et al. published a paper on historical temperature reconstruction (Ljungqvist, F.C. 2009). What interested me in Ljugzvist’s reconstruction is it is a recent mulit-proxy study that didn’t get all hung up on treemometers – the great erasers of climate bumps past. It combines 30 separate, diverse, and independently reconstructed proxy temperature records, making it a fairly robust reconstruction.
It happens that Ljugzvist, being a good scientist, made his data readily available for anyone who wanted to reproduce his work. So, I downloaded it and created a graph for my essay:
Here’s a full sized image of the graph: [URL=http://imageshack.us/photo/my-images/811/ljugzvist2010.gif/][IMG]http://img811.imageshack.us/img811/6981/ljugzvist2010.gif[/IMG][/URL]
The dark navy blue line is the averaged temperature from all 30 proxy reconstructions. The light gray lines are the error ranges. The bottom axis (the X axis) of the graph are the years. The light blue line is the linear trend of temperatures across the 2000 year span, which I threw in just out of curiosity. In his abstract, Ljungqvist names five periods which I annotated on the graph in red and blue; warmer and cooler respectively.
My interest in this study was not so much from the perspective of the temperature extents but because it showed climate shifts quite remarkably with broad Northern Hemisphere spatial coverage as well as decadal resolution. They align well with climate shifts that have been a topic of considerable discussion in the literature of cultural anthropology for some time.
There are some difficulties that need to be understood when making such correlations. There are significant regional and dating differences in historical and archeological record, partly because of limits of our ability to measure, uncertainty of historical reference points, and ambiguity of historical writings. As a result, the markers are all over the map and timeline as expected but the groupings are discernible enough to conclude there is good correlation between significant historical events identified by cultural anthropologists as being climate related and periods pointed to by Ljugzvist and other paleo-climatologists (DeMenocal 2001). Many of the historical events you’re already familiar with. Perhaps I can add a few you aren’t.
Here’s a quick tour of the five climate periods annotated on the graph punctuated with a a few historical markers that occur in close proximity of the periods. I invite you to add any events to the list in your comments.
The Roman Warm Period (RWP) – This is this period of time that Jesus lived in. It was a period of considerable agricultural expansion and cultural development. Vineyards in the south of England were plenty. Date trees grew in Greece. Olive presses were found in the Roman cities of Sagalassos in Anatolia, where it subsequently grew too cold to grow olives (Scheidel et al., 2007). The Mayan empire expanded rapidly and builds the great city of Teotihuacan in central Mexico. With a population of some 200,000 (Scher 1992) it became the cultural, religious and trading centre of Mesoamerica for a number of centuries.(FAMS). As a side note, I lived two and a half hours from Teotihuacan back in the 90’s and visited the site many times. It is an impressive display of architectural accomplishment and early mesoamerican culture.
It was hot back during the expansion of the Roman Empire (photo credit: BBC) NOTE: The plastic water bottle and color photography wasn’t invented until later. LOL!
The Dark Ages Cold Period (DACP) – This was a time where history documents a great retreat of agriculture and depression of human activity. Food was more scarce and there was considerable migration of people away from former farm lands which led to reforestation in large areas of central Europe and Scandinavia (Berglund 2003). Near the end of the DACP, “the Maya experienced a demographic disaster as profound as any other in human history,” causing a collapse of the entire civilization (Haug et al. 2001). Archeological records identify a century scale persistent drought as the cause (Haug et al. 2001, Peterson et al. 2005, Haug et al. 2003).
The great Mayan civilization collapsed and great cities were abandoned for lack of rain during the DACP (photo credit: mexicowoods.typepad.com)
The Medieval Warm Period (MWP)– The Vikings established farms and grew wheat on Greenland and modern Newfoundland (which they named Vineland or Wineland, depending on how you pronounce it). The industrial revolution began. There was considerable agricultural expansion as well as expansion of warmer climate fauna. The summer of 1130 was so dry that you could wade across the river Rhine. In 1135, the Danube flow was so low that people could cross it on foot (Behringer 2008). Productive wineries sprang up in Germany and citrus orchards sprang up in parts of Asia where later it grew too cool to sustain them (Lamb 1989).
The Vikings colonize Greenland during the MWP (photographer unknown)
The Little Ice Age (LIA) – This was a period of great upheaval and misery in human history. Fur trappers recorded that Hudson Bay remained frozen long into the spring. Eskimos were seen paddling canoes off of the coast of England, Alpine glaciers engulfed mountain villages, cold and wet weather killed farm animals and destroyed crops, the bubonic plague killed more than a third of Europeans, farms and villages in Northern Europe were deserted due to persistent crop failures, bread was made from the bark of trees because grain crops failed (Windows2Universe 2008). The famous potato famine starved over 1 million people in Ireland and caused a mass emigration of another 1 million people out of Ireland (Kinealy 1995). The Vikings left Greenland. They tried to colonize other areas in the region to maintain a population foothold but threw in the towel and left.
Viking colonies left only reminders of their presence like this stone church at Hvalsey (photographer unknown).
The Current Warm Period (CWP) – Rebounding from the LIA, we’re gradually warming up again. We are in a period where satellite imagery across 30 years shows a significant greening of the earth (Liu et al., 2010), Northern latitudes have seen higher productivity in agriculture, profitable wineries are expanding in upper New York. (one of my relatives own a winery on the Niagara escarpment), and human population has exploded along with technology, transportation, and agriculture (I don’t need to cite this – just check out the cool video games on line, hop in your car and pay a visit to the grocery store).
What else is there to say about culture in the CWP?
Some parting thoughts… There is an underlying theme in our quick tour of the periods that may be more meaningful than the periods and degree of correlation of historical events to them. Warm = good for advances in civilizations and cold = hardship and retreat. It plays out this way throughout history.
Ljungqvist, F.C. 2009; N. Hemisphere Extra-Tropics 2,000yr Decadal Temperature Reconstruction. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2010-089. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
DeMenocal (P.B.) 2001. Cultural Responses to Climate Changes During the Late Holocene. Science 292: 667-73
Bob Scher; Parabola, November, 1992
Foundation for the Advancement of Mezoamerican Studies (FAMS)
Berglund, B.E. 2003. Human impact and climate changes – synchronous events and a causal link? Quaternary International 105: 7-12.
Scheidel, Walter; Morris, Ian; Saller, Richard P. (2007). The Cambridge Economic History of the Greco-Roman World. Cambridge University Press. p. 19. ISBN 0521780535.
Wolfgang Behringer, Kulturgeschichte des Klimas: Von der Eiszeit zur globalen Erwärmung. ISBN 9783 406 52866 8 (Printed in Germany)
Larry Peterson, Gerald Haug; Climate and the Collapse of Maya Civilization, American Scientist July-August 2005
Gerald H. Haug,Detlef Günther, Larry C. Peterson, Daniel M. Sigman, Konrad A. Hughen, Beat Aeschlimann 2003; Climate and the Collapse of Maya Civilization
Haug, G.H., Hughen, K.A., Sigman, D.M., Peterson, L.C. and Rohl, U. 2001. Southward migration of the intertropical convergence zone through the Holocene. Science 293: 1304-1308.
Hubert H. Lamb: Klima und Kulturgeschichte, Reinbeck 1989
Kinealy, Christine (1995), This Great Calamity: The Irish Famine 1845–52, Gill & Macmillan, ISBN 1-57098-034-9
Windows2Universe.org Web reference: http://www.windows2universe.org/earth/climate/little_ice_age.html, last updated June 20, 2008.
Liu, S., R. Liu, and Y. Liu. 2010. Spatial and temporal variation of global LAI during 1981–2006. Journal of Geographical Sciences, 20, 323-332.