Central European Agroclimate over the Past 2000 Years

Central Europe has experienced a sequence of unprecedented summer droughts since 2015, which had con-siderable effects on the functioning and productivity of natural and agricultural systems. Placing these recent extremes in a long-term context of natural climate variability is, however, constrained by the limited length of observational records. Here, we use tree-ring stable oxygen and carbon isotopes to develop annually resolved reconstructions of growing season temperature and summer moisture variability for central Europe during the past 2000 years. Both records are indepen-dently interpolated across the southern Czech Republic and northeastern Austria to produce explicit estimates of the opti-mum agroclimatic zones, based on modern references of climatic forcing. Historical documentation of agricultural productivity and climate variability since 1090 CE provides strong quantitative verification of our new reconstructions. Our isotope records not only contain clear expressions of the medieval (920-1000 CE) and Renaissance (early sixteenth cen-tury) droughts, but also the relative influence of temperature and moisture on hydroclimatic conditions during the first mil-lennium (including previously reported pluvials during the early third, fifth, and seventh centuries of the Common Era). We conclude that Czech agricultural production has experienced significant extremes over the past 2000 years, which in-cludes periods for which there are no modern analogs.SIGNIFICANCE STATEMENT: As temperatures increase, droughts are becoming a growing concern for European agriculture. Our study allows recent extremes to be contextualized and helps to better the understanding of potential drivers. Stable carbon and oxygen isotopes in oak tree rings were analyzed to reconstruct year-to-year and longer-term changes in both temperature and moisture over central Europe and the past 2000 years. We combine these proxy-based climate reconstructions to model how well crops were growing in the past. The early fifth and the early sixteenth centu-ries of the Common Era were most likely characterized by extreme conditions beyond what has been experienced in re-cent decades. Our reconstructions of natural variability might be used as a baseline in projections of future conditions.