The BBC story is a brief review based on findings published online by the journal Science. In that report, researchers claimed to have based their data on 9,000 wooden artifacts gathered from across 2,500 years.
Simply put, researchers propose that, based on their work with the wood, “periods of warm, wet summers coincided with prosperity, while political turmoil occurred during times of climate instability.”
Using methods used to date wooden materials based on the width of rings in oak relics, the team surmised that when water was plentiful and weather was hospitable, the rings grew wider and farther apart. During times of drought, however, new rings grew close to the boundaries of the previous ones.
“Looking back on 2,500 years, there are examples where climate change impacted human history,” pronounced Ulf Buntgen, a paleoclimatologist at the Swiss Federal Research Institute for Forest, Snow and Landscape.
Once the data had been gathered and collated according to likely weather conditions, Buntgen and his 11 co-authors interpreted the findings as indicating a link between annual weather patterns and “prosperity levels in past societies, such as the Roman Empire.”
The scientists’ report explains: “Distinct drying in the 3rd Century paralleled a period of serious crisis in the western Roman empire marked by barbarian invasion, political turmoil and economic dislocation in several provinces of Gaul.”
Not hesitant to put a finer point on it, the paper declares: “Increased climate variability from 250-600 AD coincided with the demise of the western Roman empire and the turmoil of the migration period.”
Objectively, such data and the associated interpretations thereof by this team of researchers does not seem to lead to the conclusion of a causal link between climate change and the socio-economic factors that precipitated the demise of the Roman Empire. While drought and other severe climatologically-induced stresses may bear down on a great empire and its far-flung citizens, such influences surely could not break it in the manner experienced by Rome.
Gibbon, for instance, reckons that the eventual fall of Rome was attributable not to climate change, but to the succumbing to barbarian invasions in large part due to the gradual decay of civic virtue among its citizens, high and low born.
Herr Buntgen, et al, are not to be denied by traditional explanations, however widely held. They bravely beat the drum for climate change causing the attack, signaling the fall of Rome as more than a historical metaphor:
Recent warming is unprecedented, but modern hydroclimatic variations may have at times been exceeded in magnitude and duration…. Historical circumstances may challenge recent political and fiscal reluctance to mitigate projected climate change.
While the researchers findings and interpretations of the collected data are novel and curious, perhaps the cause of “political and fiscal reluctance to mitigate projected climate change” has more to do with exposed fraud than exposed tree rings.
Illustration: Roman general and politician Gaius Marius