Great Famine

The Great Famine lasted from 1315 to 1322 and was driven by severe weather and widespread crop failure across most of Europe. Volcanic ash blocking the sun directly suppressed the population's ability to synthesize vitamin D through skin exposure. The stacked effects of volcanic eruption, famine, and war systematically dismantled the immune capacity of entire populations before Yersinia pestis arrived. Mount Tarawera erupted in 1315 and volcanic ash injected into the upper atmosphere is thought to have contributed to the Great Famine by reducing solar radiation and cooling temperatures.