Natural Variability Dominates Precipitation Variability over the Past 800 Years in Eastern Europe

Abstract

Tree ring chronologies are frequently used to gain invaluable insights into past climate variability. In this study, we developed a unique 804-yr oak ring width chronology network from eastern Europe to reconstruct annual hydroclimate variability with a particular focus on the 12 July month standardized precipitation index (SPI). The SPI reconstruction captures pronounced interannual-to-multidecadal fluctuations in moisture availability, revealing sequences of persistent droughts and pluvials. These reconstructed hydroclimatic extremes align with documented historical episodes of agricultural failure, famine, and population displacement, underscoring the SPI’s potential for identifying long-term climate–society linkages. Here, we show that the hydroclimate in the eastern part of Europe has largely remained stationary from 1221 to 2019, despite exhibiting substantial variability across interannual-to-multidecadal time scales. Wet years correspond to negative geopotential height anomalies over eastern Europe, promoting cyclonic flow and rainfall, while dry years align with persistent high pressure systems that suppress precipitation and shift storm tracks northward. These circulation anomalies cooccur with coherent Atlantic sea surface temperature (SST) patterns, warm subtropical and tropical anomalies during wet years, and cold anomalies during dry years, highlighting the coupled role of blocking and ocean variability in shaping multiyear droughts and floods across eastern Europe. Comparison with bias-corrected regional climate simulations suggests little change in mean annual hydroclimate through the twenty-first century, but a broadening range of possible outcomes increases risks of persistent extremes. Our study combines tree-ring reconstructions with documentary archives to place recent and future hydroclimatic extremes in a long-term context, offering critical insights for water management, agriculture, and forestry.