Roman empire

Lees : http://www.bbc.co.uk/news/science-environment-12186245.

An extensive study of tree growth rings says there could be a link between the rise and fall of past civilisations and sudden shifts in Europe's climate. ...

"Wet and warm summers occurred during periods of Roman and medieval prosperity. Increased climate variability from 250-600 AD coincided with the demise of the western Roman empire and the turmoil of the migration period," the team reported.

"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."

Of course, of course ... Scientists have a strong need for statistics - even when they do not really understand them - and a strong need to be published. So maybe they are right (there always is a slim chance), maybe they are wrong.

But we know that a strong correlation does not necessarily indicate a link from cause to effect. "May be" has been a much used expression in science recently.