Rock Doc

Ireland enjoys a mild and stable climate. But even in Ireland there are years that stand out as unusual. Recently a team of researchers led by Harvard's Francis Ludlow announced results of a study of Ireland's climate based on the Irish Annals, a body of writings containing more than 40,000 entries.

The Annals record events from 431 A.D. to 1649 A.D. During the Medieval period they were written by monks. From the 1200s onwards some entries were written by historians of the wealthy and aristocratic families of the period. Finally, toward the end of the Annals, entries were contributed by milita...