Barley to Ice: Investigating late-winter and spring temperatures in Central Scandinavia for the last 300 years through agro- and cryophenological proxies

While most past millennium high-resolution temperature reconstructions rely on tree-ring data, there is a notable scarcity of detailed winter-spring temperature records covering the pre-instrumental period in Europe. This gap is evident in central Scandinavia, a region otherwise well covered by tree-ring data. Although tree-ring records in this area have demonstrated a correlation with spring temperatures, the climate signal is dominated by summer temperatures. Achieving a comprehensive understanding of seasonal variations is essential for understanding climate change and variability in the past. This study employs two different sets of sources to reconstruct late-winter and spring temperatures in central Scandinavia since 1697. First, agro-phenological data, covering barley sowing dates in the central agricultural district around lake Storsjön in Jämtland, central Scandinavia, are employed. These sowing dates have been shown to correlate with spring temperatures and cover most of the period since 1699. Second, previously unpublished data are employed in the form of ice-break up dates for Lake Storsjön, extending back to 1697. While each type of data cover most of the study period (1697–2021), combined they present an almost continuous time-series of phenological dates, enabling an attempt at reconstructing late-winter and spring temperatures in central Scandinavia back to 1697.