DROUGHT DOWNFALL: The record of rainfall found in tree rings suggests that the Toltec and Aztec civilizations of ancient Central America may have struggled to endure long droughts
Image: Jim G, via Wikimedia Commons
The water-stressed Central American region of today experienced super-droughts centuries ago that helped bring down two civilizations, says a study.
Using dendrochronology -- the study of tree rings -- a team from the University of Arkansas created a model using thousand-year-old Montezuma baldcypress (Taxodium mucronatum) from Barranca de Amealco in Querétaro state.
The drought observed through tree rings was "more severe and prolonged than anything we've seen in the modern era," said David Stahle, lead researcher of the study, to be published in the American Geophysical Union's Geophysical Research Letters.
The study's home base in Mexico is critical, as the climate models used by the U.N. Intergovernmental Panel on Climate Change (IPCC) to measure climatic change have predicted a "drying out" of the country leading up to 2050, said Richard Seager, a research professor at the Lamont-Doherty Earth Observatory at Columbia University, another lab that works with tree rings to decode past climate patterns.
"The fact that they occurred in the past means they could occur again," said Seager, but the events would be "much greater and more extreme."
Connie Woodhouse, a professor at the University of Arizona specializing in the climatology of western North America, said the records indicate that a similar event could happen in the future, with the added exacerbation of human-induced global warming.
"It's not a forecast or a predictive tool," she said. "It's sort of a heads-up."
Climatic conquests
Through studying bald cypress rings, the team was able to reconstruct the soil moisture balance during the rise and fall of the Toltecs and Aztecs, two of Mexico's great indigenous civilizations. The Toltecs flourished from 800 to 1000. Prime time for the Aztecs ran from 1500 to 1700.
The data identified droughts as long as 19 years, and are linked with destabilizing events that eventually brought down the Toltec state. Droughts during Aztec rule coincided with devastating famines.
The shift to a severe climate had secondary effects, as well. "Prolonged drought over Mesoamerica during the early Colonial era may have interacted with epidemic disease to contribute to the catastrophic depopulation of Aztec Mexico in the aftermath of the [Spanish] conquest," states the study.
So will modern civilizations finish off like the Toltecs? Stahle is careful not to draw a direct parallel.
"We don't know for sure if it caused a decline," he said. "We don't know for sure if it caused the collapse of the ancient city of Tula [the Toltec capital]." But the drought's role is apparent.
Dendrochronology is an effective method for constructing climate models back to 2,000 years because it directly calibrates with ancient weather patterns, said Stahle. The bald cypress is a rare variety in the region to survive more than 1,000 years. One tree in southern Mexico is ranked one of the oldest in the world.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500
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12 Comments
Add CommentThe article says "Prime time for the Aztecs ran from 1500 to 1700." Has the author of the article informed Hernando Cortes of this chronology?
Reply | Report Abuse | Link to thisJust don't understand the photo of the Mayan structure Chichen Itza!!! The Article is about Aztecs and Toltecs. what gives?
Reply | Report Abuse | Link to thisWell we've all been educated about just how accurate tree ring data is and I'm amazed the researchers would make a stretch to predict that the region will experiance a drought "sometime in the future". Amazing
Reply | Report Abuse | Link to this@Telrunya,
Reply | Report Abuse | Link to thisDid not read the article did you?
This article is full of fail. The author has confuses the Maya with the Aztecs and utterly flubbed the chronology of the Aztecs. This paper is in press and is so new that the abstract is not even available yet.
Reply | Report Abuse | Link to thisHere is URL for the paper at the Geophysical Research Letters site: http://www.agu.org/contents/journals/ViewPapersInPress.do?journalCode=GL
is this a joke??
Reply | Report Abuse | Link to thisTenochtilan, The capital of the meshica (aztec) empire, (which is not in central america) was built in the middle of a lake. The main problem were floods, not droughts. And it was bring down by the diseases brought by europeans, with a litle help of Gunpowder and military warfare..
It has been estimated that diseases killed 90% of the population of america.
(McCaa, Robert (1995). "Spanish and Nahuatl Views on Smallpox and Demographic Catastrophe in Mexico," The Journal of Interdisciplinary History, 25, 397-431. )
Tenochtitlan was destroyed in 1521, so what with: "Prime time for the Aztecs ran from 1500 to 1700."
Maybe you need to an historian to your team?...
@Nanahuaztzin,
Reply | Report Abuse | Link to thisThese history errors are not found in the paper, but in the reporting.
@ Trent1492
Reply | Report Abuse | Link to thisI though so... I was referring to the SCIAM team...
I am use to see this kind of errors when reporting about prehispanic civilizations in the media, but I never expected to see it in SCIAM... Maybe I overreact...
But I wonder if the proof readers are to much specialized?
They are not fit to proofread a comic book at Sciam Climatewire. The illustration is no different to their use of cooling tower steam to depict smokestacks.
Reply | Report Abuse | Link to thisAs for the basic tree ring data, it can be valuable. It is the cherry picking of data that causes the problems & the gravy trains supported by this falsification. Also, researchers discovering or uncovering new data often rush to interpret that data, shoehorning it to fit popular preconceptions & fads. That is nothing new. It is evident in ancient cultures too.
@ nanahuatzin,
Reply | Report Abuse | Link to thisNo, you did not overreact. The writer and editors need to hear this criticism and strive for better fact checking. These sort of glaring mistakes by the media are routinely used by the anti-science crowd such as Carlye does in the above comments, to cast doubt on the science.
For some, anti-science is anything that questions their interpretation of the evidence, even when there are legitimate alternative interpretations being proposed by other equally eminent scientists. Some do not condemn fraudulent behaviour so long as it supports their particular mind set. The famous tree ring data manipulation incident is a case in point. That is the attitude that is truly anti-science. Historically you can see it in things like the epic battle between Teslar & Edison over DC versus AC. Edison held the popular high ground for years but eventually science won. Another contemporary example is the belief in things like vitamin supplements for healthy people & numerous other health & food fads supposedly based on sound science but in fact ignoring sound scientific counter arguments. Scepticism is the truly scientific attitude that many who profess to be scientific in their approach are sadly lacking.
Reply | Report Abuse | Link to thisThis sounds quite a lot like Richardson Gill's "mega-drought" hypothesis for the Maya collapse: http://haecceities.wordpress.com/2011/02/14/yet-another-drought-explanation-for-mesoamerican-collapses/
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