Climate and the Fall of the Roman Empire

Even in our modern age, humans are incredibly vulnerable to changes in weather and climate. And earlier in human history, we were even more so. Even the Romans, who managed to build monuments, roads and aqueducts that still stand today, weren't immune, according to a new study published last week by Science.

Scientists in Germany and Switzerland created a 2,500-year-long record of Central European summer precipitation and temperature variability from nearly 9,000 samples of larch, pine and oak tree rings. They found that the region experienced above average precipitation and little temperature fluctuation up until about A.D. 250, with a couple of colder periods around 350 B.C.—when the Celtic peoples began to expand across the continent—and 50 B.C., which was when the Romans were conquering Britain.

But around A.D. 250 began a 300-year period of extreme climate variability, when there were wild shifts in precipitation and temperature from one decade to the next. The Romans didn't fare so well. The Roman Empire nearly fell during the Crisis of the Third Century and split into two in 285. In 387, the Gauls sacked Rome, followed by the Visigoths in 410 and the Vandals in 455. By 500, the western Roman Empire was gone.

"Relatively modest changes in European climate in the past have had profound implications for society," Penn State University climate scientist Michael Mann told New Scientist.

Human history shows that we don't deal well with times of climate upheaval. If things are good or bad, we can adapt if given enough time. But a small change in climate can have deadly consequences. The study also found that the period around 1300 saw wetter summers and colder temperatures; it was about that time that Europe experienced a famine and plague of such immense size that nearly half the population died.

"The provocative outcome," of the study, University of Arkansas geoscientist David Stahle told ScienceNOW, "is that harsh climate conditions happen to be associated with upheavals in society, like the Black Death."

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Sarah Zielinski is an award-winning science writer and editor. She is a contributing writer in science for Smithsonian.com and blogs at Wild Things, which appears on Science News.