Tree Rings Reveal Mesoamerican Climate Record
A new study has provided a first of its kind year by year look at the climate of Mesoamerica over a thousand-year span of time, thanks to data gathered from the annual growth rings in Montezuma bald cypresses.
As a result of the study, researchers have acquired precise dates for the duration of three historically important droughts, including one which had been hitherto unknown. One of these droughts has been dated to the years A.D. 897-927 and is thought to have hastened the decline of the Mayan culture. David Stahle, a geoscientist at the University of Arkansas, refers to this as the “Terminal Classic Drought,” since it is perhaps one of the most significant milestones in the decline of what historians refer to as the Classic period in Mesoamerica — a region that includes Mexico and Central America.
“This study is a landmark,” said Edward R. Cook, the director of the Tree-Ring Laboratory at the Lamont-Doherty Earth Observatory of Columbia University in Palisades, N.Y. “All previous studies relating drought to the demise of those cultures have relied on less well resolved and less well dated sediment core records. Further north in the U.S., similar studies had been done, but it was not possible to extend those results into central Mexico until Stahle’s results.”
The data gathered from the trees only let Stahle measure back to just prior to the 10th century, however only another century or so later and there was another drought, dated to A.D. 1149-1167 which Stahle refers to as the “Toltec Drought” as it saw the decline of the powerful Toltec nation in central Mexico. This drought took place at the same time as one playing out in the north of what is now the US.
“This was the worst drought in western North America that we know of over the last 1,200 years,” said Stahle. “Our measurements are the first to tie this drought to one taking place in Mesoamerica.”
A third drought, dated to A.D. 1378-1404 coincides with the years the Aztec nation was a relatively small power compared to the other nations in Mexico. Stahle believes that the drought may have actually worked in their favour.
Source: Inside Science
Image Source: David Stahle