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Combining historical climatology and environmental history, this article examines the diverse range of strategies deployed by the city government of Barcelona (Catalonia, NE Spain) to confront the recurrent drought episodes experienced between 1626 and 1650. Our reconstruction of drought in Barcelona for the period 1525–1821, based on pro pluvia rogations as documentary proxy data, identifies the years 1626–1635 and the 1640s as the most significant drought events of the series (highest drought frequency weighted index and drought duration index). We then focus on the period 1601–1650, providing a timeline that visualises rain rogation levels in Barcelona at a monthly resolution. Against this backdrop, we examine institutional responses to drought and discuss how water scarcity was perceived and confronted by Barcelona city authorities. Among the several measures implemented, we present the ambitious water supply projects launched by the city government, together with the construction of windmills as an alternative to watermills, as a diversification strategy aimed at coping better with diminishing water flows. We pay special attention to the institutional efforts to codify the knowledge about Barcelona's water supply, which in 1650 resulted in the Book of Fountains of the City of Barcelona (Llibre de les Fonts de la Ciutat de Barcelona). This manual of urban water supply, written by the city water officer after 3 decades of experience in his post, constitutes a rare and valuable source to study water management history but also includes significant information to interpret historical climate. We analyse the production of this manual in the context of 3 decades marked by recurrent episodes of severe drought. We interpret the city government aspiration to codify knowledge about urban water supply as an attempt to systematise and store historical information on infrastructure to improve institutional capacities to cope with future water scarcities.

This study analyzes the atmospheric variability that caused the largest floods affecting the town of Tortosa, Spain, in the mouth of the Ebro River (northeast Iberian Peninsula). The Tortosa flood database and flood marks in the nearby town of Xerta are used to define the more relevant flooding episodes (discharges >2900 m3 s−1) of the 1600–2005 period. We explore the atmospheric variability based on low-frequency patterns and synoptic types applying a multivariable analysis to grids at sea level pressure and geopotential at 500 hPa provided by the twentieth-century V3 Reanalysis Project for the instrumental period (since 1836). Output from the Last Millennium Ensemble Project was used to analyze the sea level pressure over the pre-instrumental period (before 1836). Our analysis includes 33 flood episodes. Four synoptic types are related to floods in Tortosa since 1836, characterized by low pressure systems that interact with the Mediterranean warm air mass and promote atmospheric destabilization. Flooding in Tortosa is related to relative high values of solar activity, positive Northern Hemisphere temperature anomalies, and NAO in positive phase. This result indicates that the major floods are related to zonal atmospheric circulations (west-to-east cyclone transfer). During winter, the main impact of the floods is located at the western part of the basin, and the Pyrenean subbasins are affected during autumn. The major finding is that similar flood behavior is detected since 1600, improving our understanding of past climates, enhancing the knowledge base for some aspects and impacts of climate change, and reducing uncertainty about future outcomes. Significance Statement A total of 33 large floods (>2900 m3 s−1) were registered since 1600 in Tortosa, Spain, located at the mouth of the Ebro River (northeast Iberian Peninsula). They occur associated with low pressure systems that interact with the Mediterranean warm air mass promoting atmospheric destabilization. The floods in Tortosa are also associated with other important processes occurring at significantly longer time scales: high values of solar activity, positive Northern Hemisphere temperature anomalies, and NAO in positive phase, indicating that the major floods are related to zonal atmospheric circulations. The major finding is that we detect similar flood behaviors since 1600, improving our understanding of past climates, enhancing the knowledge base for some aspects and impacts of climate change, and reducing uncertainty about future outcomes.

In the northeast of the Iberian Peninsula, few studies have reconstructed drought occurrence and variability for the pre-instrumental period using documentary evidence and natural proxies. In this study, we compiled a unique dataset of rogation ceremonies – religious acts asking God for rain – from 13 cities in the northeast of Spain and investigated the annual drought variability from 1650 to 1899 CE. Three regionally different coherent areas (Mediterranean, Ebro Valley, and Mountain) were detected. Both the Barcelona and the regional Mediterranean drought indices were compared with the instrumental series of Barcelona for the overlapping period (1787–1899), where we discovered a highly significant and stable correlation with the Standardized Precipitation Index of May with a 4-month lag (r=-0.46 and r=-0.53; p, respectively). We found common periods with prolonged droughts (during the mid and late 18th century) and extreme drought years (1775, 1798, 1753, 1691, and 1817) associated with more atmospheric blocking situations. A superposed epoch analysis (SEA) was performed showing a significant decrease in drought events 1 year after the volcanic events, which might be explained by the decrease in evapotranspiration due to reduction in surface temperatures and, consequently, the higher availability of water that increases soil moisture. In addition, we discovered a common and significant drought response in the three regional drought indices 2 years after the Tambora volcanic eruption. Our study suggests that documented information on rogation ceremonies contains important independent evidence to reconstruct extreme drought events in areas and periods for which instrumental information and other proxies are scarce. However, drought index for the mountainous areas (denoted Mountain later in the text) presents various limitations and its interpretation must be treated with caution.

The eruption of Mount Tambora (Indonesia) in April 1815 is the largest documented volcanic eruption in history. It caused a large global cooling during the following year, felt particularly in parts of Europe and North America, where the year 1816 became known as the "year without a summer". This paper describes an effort made to collect surface meteorological observations from the early instrumental period, with a focus on the years immediately following the eruption (1815–1817). Although the collection aimed in particular at pressure observations, correspondent temperature observations were also recovered. Some of the series had already been described in the literature, but a large part of the data, recently digitised from original weather diaries and contemporary magazines and newspapers, is presented here for the first time. The collection puts together more than fifty sub-daily series from land observatories in Europe and North America, and from ships in the tropics. The pressure observations have been corrected for temperature and gravity and reduced to mean sea level, moreover an additional statistical correction was applied to take into account common error sources in mercury barometers. To assess the reliability of the corrected dataset, the variance of the pressure observations is compared with modern climatologies and single observations are used for synoptic analyses of three case studies in Europe. All raw observations will be made available to the scientific community in the International Surface Pressure Databank.