Would-be emperors be warned: your empire is likely to crumble if the rains fail. Climate's role in the rise and fall of China's imperial dynasties has been established by the record in an ancient stalagmite, and now a similar record from a cave near Jerusalem adds climate change to the list of woes that forced a Roman and Byzantine retreat from the region by A.D. 700.

"Whether this is what weakened the Byzantines or not isn't known, but it is an interesting correlation," geologist John Valley at  the University of Wisconsin–Madison said in a statement about the record found in a stalagmite from Soreq Cave. "These things were certainly going on at the same time that those historic changes occurred."

Of course, a host of other factors played a role as well, not least the rise of Islam, but the drying climate can't have helped, according to the research set to be published in the journal Quatenary Research. Though this intense drought did not occur at the same time as the one that brought an end to the Tang dynasty of China and the Mayan Empire, it does potentially add another human civilization to the list of those beset by climate change.

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