Rice professor links Mayan decline to drought

By Sarah Frazier     2/12/15 5:40pm

Rice University professor of earth science Andre Droxler and a graduate student have found further evidence that the disappearance of the Mayan urban civilization was linked to a drought.

“The decline of the Maya was so unexpected...it was very fast," Droxler said. “The demise of the Maya could well be connected to this one-century drought."

Droxler said he and earth science graduate student Ayca Agar Cetin used measurements of titanium in layers of old sediment to reconstruct the rainfall history for the Yucatan Peninsula, where the Maya lived.

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“When you have … high precipitation, these metamorphic rocks are going to be altered chemically and release titanium," Droxler said. “[The titanium] goes to this lagoon, it settles down, and you have a kind of a record.”

The team used X-ray fluorescence to identify the elements in cores of sediment from a location off the coast of Belize.

“You can scan the core, and it gives you certain elements," Droxler said. “You could see there was a trend [in the titanium measurements].”

According to Droxler, they compared the measurements of titanium and aluminum in this sediment to estimate how much rain there was in the region during that time — more titanium means more precipitation.

“This titanium aluminum ratio becomes a precipitation record,” Droxler said. “We call this a paleo-precipitation proxy.”

Using X-ray fluorescence, they identified a century-long period of low titanium, which meant there had been very little rainfall during that time. The drought period corresponds to the time the Maya abandoned their southern urban civilization, Droxler said.

“The Maya kind of disappeared between 800 and 900,” Droxler said. “Some of them migrated … [to] the northern side of the Yucatan Peninsula [at] Chichen Itza.”

Droxler said another major Maya city, Chichen Itza, was abandoned about 150 years after the southern urban civilization.

“Chichen Itza was abandoned at 1040,” Droxler said. “[1000-1100] is another point where you have low precipitation.”

Droxler’s work is just another piece of evidence pointing toward the idea that drought was a major factor in the demise of the Maya urban civilization.

“There are at least three different types of paleo-precipitation records [that support this], plus [the] tropical cyclone record.” Droxler said.

Another study that Droxler collaborated on used sediment samples to show there were fewer tropical cyclones during these periods, which supports the drought hypothesis, Droxler said.  

“When you have … very little precipitation, you have no cyclone,” Droxler said.

Droxler says an understanding of how climate affected the Maya civilization is more than just historically interesting.

“It’s very important for us to study the past … to try to assess the change in climate we’ve witnessed in the past 50 years,” Droxler said. “How will our civilization … react to this change of climate?”

Droxler said a drought of even a few years can significantly change an area.

“The summer [of 2011] with no rain, in Memorial Park we lost one-third [to] one-half of all the trees,” Droxler said. “Imagine if that summer [were] three or four years in a row. South Texas would have changed completely.”

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