Christian Rohr

The year-long unprecedented European heat and drought of 1540 – a worst case

The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in the global warming-influenced future. However, a recent reconstruction of spring–summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km2, we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models.

Floods of the Upper Danube River and Its Tributaries and Their Impact on Urban Economies (c. 1350–1600): The Examples of the Towns of Krems/Stein and Wels (Austria)

This paper examines the impact of disastrous and ‘ordinary’ floods on human societies in what is now Austria. The focus is on urban areas and their neighbourhoods. Examining institutional sources such as accounts of the bridge masters, charters, statutes and official petitions, it can be shown that city communities were well acquainted with this permanent risk: in fact, an office was established for the restoration of bridges and the maintenance of water defences and large depots for timber and water pipes ensured that the reconstruction of bridges and the system of water supply could start immediately after the floods had subsided. Carpenters and similar groups gained 10 to 20 per cent of their income from the repair of bridges and other flood damage. The construction of houses in endangered zones was adapted in order to survive the worst case experiences. Thus, we may describe those communities living along the central European rivers as ‘cultures of flood management’. This special knowledge vanished, however, from the mid-nineteenth century onwards, when river regulations gave the people a false feeling of security.

Tree-rings and people – different views on the 1540 Megadrought. Reply to Büntgen et al. 2015

Buntgen et al. (2015; hereinafter B15) present the result of new research which question the results of Wetter et al. 2014, (hereinafter W14) and Wetter et al. (2013, hereinafter W13)regarding European climate in 1540. B15 conclude from tree-ring evidence that the results based on documentary data of W14 probably overstated the intensity and duration of the 1540 drought event. W14 termed it Megadrought because of its extreme duration and spatial extent compared to other drought events in central Europe, although they note that the term is generally used for decadal rather than for single-year droughts (Seneviratne et al. 2012). We take the opportunity to recall the following issues. Firstly, when dealing with drought the complexity of this phenomenon should be kept in mind. Meteorological drought defined as a large negative precipitation anomaly during a certain period can trigger agricultural, hydrological, groundwater and socioeconomic droughts. Lloyd-Hughes (2013] and references cited herein) concluded that any workable objective definition of drought does not exist. To quantify droughts, various indices based on precipitation, temperature and evapotranspiration are used such as the Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), Z-index and PDSI. Their calculation depends on different periods (seasons, combination of months) and so different indices may classify the same drought episode differently (e.g. Brazdil et al.2014).

An empirical perspective for understanding climate change impacts in Switzerland

Planning for the future requires a detailed understanding of how climate change affects a wide range of systems at spatial scales that are relevant to humans. Understanding of climate change impacts can be gained from observational and reconstruction approaches and from numerical models that apply existing knowledge to climate change scenarios. Although modeling approaches are prominent in climate change assessments, observations and reconstructions provide insights that cannot be derived from simulations alone, especially at local to regional scales where climate adaptation policies are implemented. Here, we review the wealth of understanding that emerged from observations and reconstructions of ongoing and past climate change impacts in Switzerland, with wider applicability in Europe. We draw examples from hydrological, alpine, forest, and agricultural systems, which are of paramount societal importance, and are projected to undergo important changes by the end of this century. For each system, we review existing model-based projections, present what is known from observations, and discuss how empirical evidence may help improve future projections. A particular focus is given to better understanding thresholds, tipping points and feedbacks that may operate on different time scales. Observational approaches provide the grounding in evidence that is needed to develop local to regional climate adaptation strategies. Our review demonstrates that observational approaches should ideally have a synergistic relationship with modeling in identifying inconsistencies in projections as well as avenues for improvement. They are critical for uncovering unexpected relationships between climate and agricultural, natural, and hydrological systems that will be important to society in the future.

Climate and Beyond. The Production of Knowledge about the Earth as a Signpost of Social Change. An Introduction

»Klima und anderes mehr. Wissensproduktion über die Erde als Indikator für Sozialen Wandel. Eine Einleitung«. Environmental history and the history of the earth and environmental sciences are now converging in three fields of research: analyzing the politics of deep time, reconstructing the making of natural disaster knowledge, and exploring the national and transnational devices and strategies of earth governance established in the twentieth century. We argue that including the global physical world in our historical analysis will help us to better understand the social world – past and present.

Historical weather data for climate risk assessment: Historical weather data for climate risk assessment

Weather‐ and climate‐related hazards are responsible for monetary losses, material damages, and societal consequences. Quantifying related risks is, therefore, an important societal task, particularly in view of future climate change. For this task, climate risk assessment increasingly uses model chains, which mainly build on data from the last few decades. The past record of events could play a role in this context. New numerical techniques can make use of historical weather data to simulate impacts quantitatively. However, using historical data for model applications differs from using recent products. Here, we provide an overview of climate risk assessment methodologies and of the properties of historical instrumental and documentary data. Using three examples, we then outline how historical environmental data can be used today in climate risk assessment by (1) developing and validating numerical model chains, (2) providing a large statistical sample which can be directly exploited to estimate hazards and to model present risks, and (3) establishing “worst‐case” events which are relevant references in the present or future. The examples show that, in order to be successful, different sources (reanalyses, digitized instrumental data, and documentary data) and methods (dynamical downscaling and analog methods) need to be combined on a case‐by‐case basis.

Die sakramentale Kraft des Wassers. Scholastische Debatten über ein augustinisches Bild zur Wirkweise von Weihwasser und Taufe

„Whence has water so great an efficacy, as in touching the body to cleanse the soul?“ This famous question from Augustine’s , Tractates on the Gospel of John‘ – rhetorically asked with regards to Baptism – was for centuries the object of concern for medieval theologians trying to explain the efficacy of the sacramental administration of grace. In particular, the striving for rationality within late medieval scholasticism seemed to encounter insurmountable limits, for, how should it be that a corporeal element such as water operated with something as spiritual as grace? How should a natural event such as the contact with water produce a supernatural purification of the soul? Augustine’s own answer, that this was due to the belief in the accompanying words, was only one of several models that late medieval scholasticism developed and transferred from the question of sacramental efficacy to related problems such as the efficiency of holy water. Starting with a late scholastic tract on holy water, the , De efficacia aquae benedictae‘ of Juan de Torquemada (written ca. 1437 at the council of Basel), this contribution explores the different models of explanation for the special power of water and illustrates the role that the particular properties of water assumed for the development of a general theology of the sacraments.

Zur Einführung. Wasser in der mittelalterlichen Kultur

Water is life. Individual organisms, social formations, and cultural achievements all depend on water. It is used in both pragmatic and symbolic contexts. Being a life-sustaining as well as a destructive force, water connects and divides, absolves and dissolves. Society as a whole and individual institutions alike need to engage with, and adapt to, these ambivalent aspects of water. As a natural element, water provokes cultural reactions in regard to its utilisation, evaluation, and symbolism. The different functions water fulfils in the natural world are also addressed and negotiated in literature and the visual arts. This article provides a short introduction into the main research questions of the interdisciplinary conference of the “Mediavistenverband e. V.” held in Bern, Switzerland in March 2015, it gives a concise overview on previous publications in this field and it summarizes the findings of the overall volume.

December 1916: Deadly Wartime Weather

One of the worst meteorological disasters in history took place in the southeastern Alps during the infamous winter of 1916 / 17. Avalanches following a massive snowfall event killed thousands of soldiers as well as civilians. Novel insight into the event arises from a detailed reconstruction based on weather forecast models and shows the potential of combining numerical techniques with historical documents. This helps to better understand worst-case weather events in the past and future and their societal impacts.

Erratum to: The year-long unprecedented European heat and drought of 1540 – a worst case

Oliver Wetter & Christian Pfister & Johannes P. Werner & Eduardo Zorita & Sebastian Wagner & Sonia I. Seneviratne & Jurgen Herget & Uwe Grunewald & Jurg Luterbacher & Maria-Joao Alcoforado & Mariano Barriendos & Ursula Bieber & Rudolf Brazdil & Karl H. Burmeister & Chantal Camenisch & Antonio Contino & Petr Dobrovolný & Rudiger Glaser & Iso Himmelsbach & Andrea Kiss & Oldřich Kotyza & Thomas Labbe & Danuta Limanowka & Laurent Litzenburger & Oyvind Nordli & Kathleen Pribyl & Dag Retso & Dirk Riemann & Christian Rohr & Werner Siegfried & Johan Soderberg & Jean-Laurent Spring