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While the impacts of modern farming and land use practices on climate and biodiversity since 1900 are well-studied in Western and Central Europe, less is known about the preceding transitional period of the 18th and 19th century. By combining information from both natural and historical archives, this study strives to understand the impacts of 18th century agrarian modernisation on Central European ecosystems. Here we present a multi-proxy palaeoecological study from Egelsee (548 m a.s.l., within the city of Bern, Switzerland) spanning the late Middle Ages to the early 20th century. We use pollen, charcoal, dung fungal spores and spheroidal carbonaceous particles (SCPs) as proxies for vegetation and land use changes as well as radiocarbon wiggle matching for the chronology. Our pollen record suggests a shift from cereal cultivation towards grazing from the 16th century onwards, and from the 18th century towards fertilised meadows for animal husbandry. The pollen-inferred decrease of woods since 1700 quantitatively confirms the historically described timber scarcity in the lowlands of Switzerland, while the positive correlation between climate indices and our pollen-inferred cereal production suggests a certain vulnerability of societies to subsistence crises. From the 1850s, urbanisation rapidly altered the vegetation from an open agricultural landscape to a highly urbanised area, leading to a decline of biodiversity towards the present. This study shows that historically well-documented changes in agricultural practices in livestock farming and fodder production, and later urbanisation, can likewise be reconstructed with palaeoecological approaches. Our interdisciplinary approach provides new insights into how agricultural innovations affected vegetation and ecosystems during the past 500 years.

There are concerns that recent climate change is altering the frequency and magnitude of river floods in an unprecedented way1. Historical studies have identified flood-rich periods in the past half millennium in various regions of Europe2. However, because of the low temporal resolution of existing datasets and the relatively low number of series, it has remained unclear whether Europe is currently in a flood-rich period from a long-term perspective. Here we analyse how recent decades compare with the flood history of Europe, using a new database composed of more than 100 high-resolution (sub-annual) historical flood series based on documentary evidence covering all major regions of Europe. We show that the past three decades were among the most flood-rich periods in Europe in the past 500 years, and that this period differs from other flood-rich periods in terms of its extent, air temperatures and flood seasonality. We identified nine flood-rich periods and associated regions. Among the periods richest in floods are 1560–1580 (western and central Europe), 1760–1800 (most of Europe), 1840–1870 (western and southern Europe) and 1990–2016 (western and central Europe). In most parts of Europe, previous flood-rich periods occurred during cooler-than-usual phases, but the current flood-rich period has been much warmer. Flood seasonality is also more pronounced in the recent period. For example, during previous flood and interflood periods, 41 per cent and 42 per cent of central European floods occurred in summer, respectively, compared with 55 per cent of floods in the recent period. The exceptional nature of the present-day flood-rich period calls for process-based tools for flood-risk assessment that capture the physical mechanisms involved, and management strategies that can incorporate the recent changes in risk.

The city archive of Wels (Upper Austria) has long time series of accounts, written by the bridge master of Wels. This municipal official was responsible for carrying out repairs to the bridge across the Traun River, one of the major tributaries of the Danube River in Austria. The accounts contain detailed information about the expenses for the craftsmen who performed repairs after the floods. These expenses serve as an important measure of the impact of floods on the bridge. In most cases, it is possible to reconstruct the frequency, duration and intensity of floods, and to date them. The accounts on the “disastrous floods” of 1501, 1567, 1569 and 1572 provide a vivid impression of the management of these floods. Comparing the intensity of these floods with data from Bohemia and Germany, it becomes clear that most of the major floods in modern Austria have been merely regional hazards.