Decline of Roman and Byzantine Empires 1, 400 years ago may have been driven by climate change

A team of American and Israeli geologists have put together a much more detailed than previously possible climate record from 200 BCE to 1100 CE from geochemical analysis of a stalagmite from Soreq Cave near Jerusalem. Using an advanced ion microprobe they measured oxygen isotope signatures and impurities in the mineral layers of a stalagmite to sufficient resolution to be able to tell the rainfall for individual years and seasons. They were thus able to build up a detailed picture of the climate.

And they found the weather between 100 and 700CE became increasingly dry with "steep drops in precipitation" between 100 and 400 CE, a period that coincides with a drop in power and influence of the Roman and Byzantine Empires in the region. University of Wisconsin-Madison Professor John Valley said "Whether this is what weakened the Byzantines or not isn't known, but it is an interesting correlation."