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The European Great Famine of 1315���1317 triggered one of the worst population collapses in European history and ranks as the single worst European famine in mortality as a proportion of population. Historical records point to torrential rainfall, land saturation, crop failure, and prolonged flooding as important causes of the famine. Here we use the tree-ring based Old World Drought Atlas (OWDA) to show that the average of each growing season preceding the Great Famine years (1314���1316) was the fifth wettest over Europe from 1300 to 2012 C.E. The spatial and temporal characteristics of our OWDA-estimated anomalies are in excellent agreement with available historical accounts. We also characterize a mode of European hydroclimate variability that is associated with the Great Famine, which we term the ���Great Famine mode.��� This mode emerges as the leading mode of European hydroclimate variability from 1300���2012 and is strongly associated with extreme wet and dry events in Europe over the last millennium.

Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geology or Earth and Environmental Sciences, Department of Earth and Environmental Sciences, During the Mid-Miocene Climatic Optimum (MMCO, 14.7-17.3 Ma), global temperatures were warmer than present, and similar to predicted temperatures for the coming century. Limited paleoclimate data exists from the tropics during this period, despite its potential as an analog for future climate conditions. This study presents new subannual stable isotope data (��18O and ��13C) from a large population of Miocene Turritella gastropods from the Jimol and Castilletes formations of the Guajira peninsula, Colombia. Turritellids are aragonitic marine mollusks that live in shallow coastal waters, and their rapid growth rates allow for high-resolution subannual records. We compare these fossils to modern Turritella gastropods from multiple tropical localities to reconstruct subannual climate conditions. The seasonal range in ��18O in the modern shells correlates with the seasonal variance of local precipitation, once temperature seasonality is accounted for. The Miocene fossils show larger (sometimes >2���) seasonal variation in ��18O than modern Turritella from the same location, suggesting increased seasonality of precipitation in Miocene northern Colombia relative to today. We propose that this increased seasonality of precipitation was due to a more northerly position of the ITCZ during the Mid-Miocene. The resulting wet Miocene paleoenvironment is in stark contrast to semi-arid conditions on the Guajira Peninsula today, indicating that this area of tropical South America has undergone a drastic environmental change since the Miocene.