Comparing climate variability with historical datasets from Cyprus: significance, strengths and limitations

Comparing long-term climate variability with documentary data for the last millennium is challenging in regions where well-resolved natural records are lacking. In Cyprus, historical data of famine outbreaks, plagues and locust waves were retrieved from a variety of historical documents. These events are considered as societal indicators as they reflect the vulnerability of the Cypriot society towards environmental and climatic change from the late Lusignan’s to the Early British colonial period. The aim of this study within the HIGH-PASM project is to explore the relationship between local climate variability and locust waves, plagues and famine outbreaks.

An 8 cm-high actively growing stalagmite was collected from Hot cave in the Kyrenia range (Cyprus). U-Th dating and lamina counting were combined to produce an age model of the last ~700 years. We applied high-resolution stable isotopic (ẟ¹⁸O, ẟ¹³C) and trace element (Mg, Sr) analyses to establish climate proxy records and compare them to historical records and observational data. First, statistical analyses (normalization, volatility) were conducted on the isotope time-series to evaluate the intensity of humid/dry peaks and to identify periods with strong/weak fluctuations. Second, 875 recorded events were compiled from various historical sources (primary, secondary, compilations) and homogenized. Third, both natural (continuous) time-series and historical (discrete) data were compared using several statistical methods. 

The comparison between the occurrence of these three types of historical events shows that 36% of locust waves and famines occurred within the same year and a similar synchronicity was found between famines and plague outbreaks. Plagues and locust waves, however, did not occur significantly synchronously. Statistical analyses between the ẟ¹³C volatility index and the number of locust waves, plagues, and famines show whether certain combinations of dry/wet and volatile/non-volatile conditions promote any of the three different disasters. Early results show that all three types of events occurred during wet and non-volatile (low signal oscillation) periods. This is consistent with the ecological niches of Dociostaurus maroccanus (locust specie) and Yersinina pestis (zoonotic bacterium that causes plague) which require a slightly wet climate to proliferate. However, this applies less to famines, as many famines also occurred during dry periods (e.g., in the 19^th century).