This time it’s drought. There have been so many reasons put forward that if they are all true it’s a wonder the poor Romans survived as long as they did.
WASHINGTON: New clues unearthed by geologists suggest that a drought may have lead to the decline of the Roman civilization more than a millennium ago.
According to a report in Discovery News, the researchers used a new technique to figure out exactly how much rain fell in the Eastern Mediterranean between about 1,000 and 2,000 years ago.
Using a tool called an ion microprobe, the researchers were able to look at single layers of stalactite that were just 1/100th of a millimeter thick – 100 times thinner than what scientists can analyze with standard techniques.
Like a tree’s growth rings, stalactites grow in layers from the top of a cave downward. In each layer, a preserved chemical signature called the oxygen isotope ratio reveals whether a particular period was especially wet or dry.
Orland and University of Wisconsin geologist John Valley used a new generation ion microprobe to analyze a stalactite sample form Israel’s Soreq Cave, one of the best-studied caves in the world.
Compared to standard methods, the new technique revealed four times as much variability in rainfall during the period covered by the sample – from 2,200 to 900 years ago. In some stretches, the scientists were able to pinpoint what the region’s weather was like from one week to the next, by far the most detailed climate history ever produced.
The results showed a gradual drying between about 100 and 700 A.D., with sharp drops in rainfall at 100 AD and 400 AD.
Overall, annual rainfall fell 50 percent during those centuries, dropping from an average of more than 3 feet per year to 1.6 feet.
During the same period, Roman rule declined in the area. This is the first study to link the two events.
“Such a large change in rainfall may have played an important part in the historical events that took place in that region at that time,” said Ian Orland, a Ph.D. candidate in geology at the University of Wisconsin, who co-led the study.
The drastic change in climate would have had a profound effect on the people living in the region, the researchers speculate.
As their crops suffered, the Romans probably began to struggle until finally succumbing to the growing Islamic empire at the Battle of Yarmouk in 636 AD.
Future work will attempt to confirm these results with other samples and look for similar data in other regions.