More of a meta-answer; sorry mods.

I actually think this fits better with /r/askscience as climatologist and ecologists have extensively studied the climate of the recent past and the Mediterranean and human influence on its ecology (timber industry especially) features prominently.

You should try asking over there as well.

If the OP doesn't mind a bit of a deviation from his original question, I am also curious about the extent of forests in other parts of Europe. Greek and Roman sources repeatedly mention the "vast Hercynian Forest", beginning with Aristotle in Meteorologica. Caesar mentions it in his commentaries on the Gallic wars, describing it as beginning at the frontiers of the Helvetians/Nemetes/Rauraci (modern Switzerland?) and extending all the way east to the Daci and Anartes (I guess that would be modern Romania to the Carpathians, blending in with the forests of Transylvania). Relicts of this forest still exist in patches today - the Black Forest, Odenwald, Thuringian Forest, Bohemian Forest, and probably a dozen others.

It was described as very dense and trackless, full of huge oaks (and many unbelievable creatures, which were probably fanciful additions by later commentators), blocking Caesar's legions from entering Germania.

Apparently, it still existed in early medieval times, in fact, what first caught my attention was a few lines from William Manchester's A World Lit Only by Fire:

Surrounding them was the vast, menacing, and at places impassable, Hercynian Forest, infested by boars; by bears; by the hulking medieval wolves who lurk so fearsomely in fairy tales handed down from that time; by imaginary demons; and by very real outlaws, who flourished because they were seldom pursued. Although homicides were twice as frequent as deaths by accident, English coroners’ records show that only one of every hundred murderers was ever brought to justice. Moreover, abduction for ransom was an acceptable means of livelihood for skilled but landless knights. One consequence of medieval peril was that people huddled closely together in communal homes. They married fellow villagers and were so insular that local dialects were often incomprehensible to men living only a few miles away.

I know Manchester isn't the most reliable of historians, but he paints a very romantic picture of little villages separated by vast stretches of impenetrable or difficult-to-traverse forest which was full of lurking dangers. It kind of puts context to old fairy tales like Red Riding Hood or Hansel and Gretel or Little Briar Rose, where the forest looms so large in their imaginations and is an integral part of the stories.

Of course, accounts like "being able to swing from tree to tree never touching ground across the whole breadth of Spain" are clearly exaggerations, but I wonder about the extent of European forests in ancient and early medieval times, and how they impacted the lives and thoughts of the people. It must have been a very different world!