At http://news.sciencemag.org/paleontology/2011/01/fall-rome-recorded-trees … an analysis of European tree ring data suggests that a series of mild summers may have been the key to the rise of the Roman Empire – and prolonged droughts, cold snaps, and the like played a part in historical upheavals, from the barbarian incursions to the Black Death (plague). Ulf Buntgen, a palaeoclimatologist from Zurich had his paper published in the journal Science (www.sciencemag.org/content/331/6017/578.short … in January of 2011). The study used 7284 oak samples from France and Germany and 1500 pine tree samples from Austria, in order to set up a temperature record over 2500 years. During the Roman period Europe experienced warm wet summers, ideal for agriculture. Similar conditions prevailed in the Medieval Warm Period (950-1200). Climate and catastrophe also lined up. Extended droughts during the 3rd century AD coincided with barbarian invasions from the north, cold weather, and political turmoil. Again, around AD1300 cold weather, and very wet summers coincided with famines – leading up to the plague.
At http://dendro.cornell.edu/projects/aegean.php … the tree ring laboratory at Cornell was involved in the Aegean dendrochronology project – not altogether successful. There are apparently gaps in the tree ring chronology – best seen at the graph at http://dendro.cornell.edu/photo.php?photourl=/images/charts/bargraph.jpg .. to wit, during the Roman period, at at the end of the Early Bronze Age.
The bargraph link is also at the Cornell web page.