By Andrew Curry , Science. Excerpt: The Black Death is the single most deadly documented pandemic in human history. In 1347 C.E., it spread from a few Italian port cities to nearly every corner of Europe, killing tens of millions of people within a decade and eliminating more than half the continent’s population. In a paper published today in Communications Earth & Environment , researchers argue that cool weather spurred by previously unidentified volcanic eruptions set into motion a deadly chain of events. ...The authors of the new paper suggest volcanic eruptions a few years before the plague’s rapid spread played a role, by pushing plumes of sulfur high into the atmosphere that cooled parts of Europe and caused harvests to fail around the Mediterranean. These failures, in turn, forced Italian cities to import large quantities of grain from the plague-wracked Black Sea region—along with infected fleas, capable of subsisting on grain dust in the cargo holds...