According to a report in The Australian, the team comprised of Sydney University archeologist Roland Fletcher and his GAP (Greater Angkor Project) co-director, Sydney University paleo-climatologist Dan Penny, and paleoclimatologist Brendan Buckley of New York's Columbia University. The scientists used new archeological, pollen and tree-ring dating evidence to back their claims.
The group argues that before an alternating series of droughts and monsoonal floods hit Angkor from the mid-14th to late 15th centuries, the capital of the Khmer empire had already had extensive problems with its vast, complicated water system.
Ultimately, it became impossible for the city to keep pace with further pressures from extreme weather. "Although there was ongoing conflict with neighbouring states, it was this over-built, inflexible (water) infrastructure that locked them into this trajectory of decline," Dr Penny said.
Before Angkor vanished into the jungle in the 17th century, it was the world's largest low-density pre-industrial city. Between the ninth and 13th centuries, the metropolis spread across 1000sq km and was home to as many as 750,000 people. To feed the population, land was extensively cleared for rice farming and hundreds of kilometres of canals and enormous reservoirs were built to provide water for farming and drinking.
The water works also supported religious ceremonies at hundreds of temple complexes. The most spectacular was Angkor Wat, the world's largest premodern religious monument. "It was the size of a medieval European town," Professor Fletcher said.
As the city grew, so did the highly integrated system of canals, spillways and reservoirs needed to support it. Sand had begun filling major canals from the 14th century. Spillways and other features of the waterworks were badly damaged and shut down. By the late 16th century, Angkor was largely abandoned, taking with it the entire region.
According to Professor Fletcher, Angkor is not the only city that fell victim to unsustainable low-density urban sprawl followed by climate instability. "The famous example is the classic Maya cities of the Yucatan Pensinsula like Tikal in Guatemala. They died between the ninth and the 11th century," he said.