Climate change helped bolster -- and then torpedo -- the Classic Maya culture in South America, according to a new study.

The findings, published yesterday in Science, are based on rainfall records reconstructed by analyzing a chunk of stalagmite collected from a cave in Belize, in an area near many important Classic Maya sites.

The analysis suggests the civilization -- which existed from roughly A.D. 300 to 1000 -- thrived during wet periods and collapsed as drought developed, devolving into a society riven by fighting and famine.

"We propose that a two-stage collapse commenced with the [A.D.] 660 drying trend," the study's authors write. "It triggered the balkanization of polities, increased warfare, and abetted overall sociopolitical destabilization."

Between A.D. 800 and 900, two multi-decadal droughts further cut crop yields and increased political tensions, and the population continued to decline through an extreme drought between A.D. 1020 and 1100, the scientists said.

Their analysis adds to an ongoing debate about the role climate played in the rise and fall of the vast, sophisticated Classic Maya civilization, which produced advances in language, astronomy, art and architecture, including massive stepped temples.

Drought at the heart of collapse

Earlier studies suggested drought helped bring about the society's collapse, based on close examination of tree rings and sediment records.

But many of those records were collected in areas relatively distant from the area where the Classic Maya empire thrived, or included significant uncertainty in estimates of the timing and duration of wet and dry periods.

The new study's authors, a team of climate scientists and archaeologists from the United States and Europe, say their reconstruction of the climate the Classic Maya experienced avoids those difficulties.

Their analysis is based on a 22-inch chunk of stalagmite collected in 2006 from Yok Balum Cave in Belize, roughly a mile from the ancient city of Uxbenka and within 125 miles of several other important Classic Maya sites.

By analyzing changes in the isotope content of the stalagmite, researchers were able to tease out variations in rainfall over intervals as small as six months, with a margin of error ranging from one to 17 years.

They compared the record they put together with political events memorialized, with dates, on carved stone monuments created by the Maya.

That carving ended as the civilization collapsed, between A.D. 800 and 1000.