By ScienceAdviser.  Excerpt: Historians have long debated the reasons why the Roman Empire—which once stretched across the Mediterranean sea and from northern Africa to the U.K.—collapsed. Recently, some have pointed to a sudden period of cooling called the Late Antique Little Ice Age. This cold spell could have hindered agricultural production,  facilitated disease outbreaks , and driven people to migrate. According to a new paper,  serendipitously discovered rocks on the shore of Iceland add to the evidence for this chilly period . ...the change in climate may have compounded the troubles of an empire that was already in decline. “ When it comes to the fall of the Roman empire, this climate shift may have been the straw that broke the camel’s back ,” co-author Tom Gernon told  The Independent. ...