A climate for the demise of the Maya - Droughts' role in collapse of ancient culture may hold a lesson for us, study finds

www.nj.com Friday, March 14, 2003 BY KITTA MacPHERSON Star-Ledger Staff

Scientists have decoded a grave lesson from the past that they say could shed light on whether global climate change really matters.

A long period of dry climate, punctuated by three intense droughts, probably played a major role in the collapse of Mayan civilization, researchers report today in the journal Science.

Studying ancient cores of mud drilled from the Cariaco Basin off the coast of Venezuela, researchers have found that the prolonged dry spell, with 10-year droughts in the years 810, 860 and 910, doomed a culture renowned for its wealth, might, art and inventiveness.

"Here they were, this prospering civilization with a relatively large population that was very active in agricultural pursuits, and they apparently suffered due to natural climate change," said Daniel Sigman, an assistant professor of geosciences at Princeton University and one of the authors of the study. "I'm not totally confident that we would do better than the Maya."

The Mayan civilization was at its peak from about 250 to 900. During that time, known as the Classic Period, it was centered in the tropical rain forest of the lowlands of what is now northern Guatemala. Many of the major Mayan cities, such as Piedras Negras, Tikal and Uaxactun, developed in this area.

Living in both desert and cleared jungle and depending on an inconsistent rainfall cycle, the Maya developed a variety of reservoirs, canals and other systems for catching and storing rainwater.

Until now, climate records from this time period have not been precise enough to test the relationship between the Maya's mysterious decline during the ninth and tenth centuries, Sigman said.

The scientific team, with members drawn from Switzerland, Florida, Massachusetts and New Jersey, was searching for clues about ancient climate in sea sediments, a field known as paleoceanography. To do this, the researchers scooped long cylinders of mud from the deep, undisturbed Cariaca Basin.

They identified annual variations in titanium levels, which reflect the amount of rainfall each year. The pristine sediment layers in the basin form distinct bands, corresponding to yearly dry and wet seasons.

The three drought periods identified through the samples correspond to the three phases of Mayan collapse suggested by archeological evidence. The three droughts may have been what "pushed Mayan society over the edge," the authors wrote.

By about 900, most of the Maya abandoned the Guatemalan lowlands and moved to areas to the north and south, including Yucatan and the highlands of southern Guatemala. In those areas, they continued to survive until Spain conquered almost all of the Maya in the mid-1500s.

Today, descendants of the Maya live in Mexico and Central America. They speak Mayan languages and carry on some religious customs of their ancestors.

The results also suggest that a more subtle but long-term drying trend was occurring during the collapse.

"This fits, it makes sense," said Gillett Griffin, the faculty curator of ancient American art at the Princeton University Art Museum. "It corroborates what I thought must have happened."

The Mayan civilization reached its period of greatest development in the year 250. They produced remarkable architecture, painting, pottery and sculpture. They made great advances in astronomy and mathematics and developed an accurate yearly calendar. They were one of the first peoples in the Western Hemisphere to develop an advanced form of writing.