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Documentary climate data describe evidence of past climate arising from predominantly written historical documents such as diaries, chronicles, newspapers, or logbooks. Over the past decades, historians and climatologists have generated numerous document-based time series of local and regional climates. However, a global dataset of documentary climate time series has never been compiled, and documentary data are rarely used in large-scale climate reconstructions. Here, we present the first global multi-variable collection of documentary climate records. The dataset DOCU-CLIM comprises 621 time series (both published and hitherto unpublished) providing information on historical variations in temperature, precipitation, and wind regime. The series are evaluated by formulating proxy forward models (i.e., predicting the documentary observations from climate fields) in an overlapping period. Results show strong correlations, particularly for the temperature-sensitive series. Correlations are somewhat lower for precipitation-sensitive series. Overall, we ascribe considerable potential to documentary records as climate data, especially in regions and seasons not well represented by early instrumental data and palaeoclimate proxies.

There are concerns that recent climate change is altering the frequency and magnitude of river floods in an unprecedented way. Historical studies have identified flood-rich periods in the past half millennium in various regions of Europe. 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 abstract is included in the text.

En este trabajo se analiza la influencia de la Oscilación del Atlántico Norte (NAO) en la covariabilidad de temperaturas y precipitaciones de invierno de 18 estaciones meteorológicas distribuidas por el territorio peninsular español durante el periodo 1946-2005. La covariabilidad entre precipitaciones totales acumuladas (R) y media estacional de las temperaturas máximas diarias (TX), mínimas diarias (TN), medias diarias (TM), y del rango diurno de temperaturas (DTR), fue analizada comparando los resultados obtenidos para las distintas fases de la NAO. Entre las variables relacionadas con la temperatura, la que muestra mayor cobertura espacial de resultados estadísticamente significativos es la DTR. Entre los principales resultados se obtiene el descenso (aumento) de los valores medios de DTR durante la fase NAO negativa (positiva), aunque no hay cambios importantes en las correlaciones entre variables dependiendo de las fases de la NAO. En términos generales, y durante la fase NAO negativa (positiva), se produce un aumento (descenso) de la covariabilidad de temperaturas y precipitaciones en las estaciones occidentales, mientras que el comportamiento opuesto se detecta en las estaciones del litoral mediterráneo., The influence of the North Atlantic Oscillation (NAO) on the covariability of temperatures and precipitation in 18 stations of the Iberian Peninsula during the period 1946-2005 is analyzed in this work. Daily data of minimum, maximum, mean temperature, and daily temperature range were used to obtain seasonal means (TN, TX, TM, and DTR, respectively), and the covariability of these variables with accumulated seasonal rainfall (R) was studied comparing results obtained for different NAO phases. The variable that shows the greatest spatial coverage of statistically significant results is the DTR. It has been detected a decrease (increase) of DTR during the negative (positive) NAO phase, although there is not important differences of the correlations depending on the NAO phases. In general terms, during the negative (positive) NAO phase, there is an increase (decrease) of the covariability of temperatures and rainfall in western stations, while the opposite behavior is found in the Mediterranean stations.

The semiarid SE fringe of the Iberian Peninsula is considered one of the most sensitive to extreme floods and droughts in the western Mediterranean area. The controlling climatic mechanisms are nevertheless difficult to predict and model. A combined documentary-sedimentary-instrumental 500 years comprehensive register of climatic data (rainfall and flooding) was collated for analysing the decadal to centennial scale hydrological response. Wet years are closely linked to the presence of autumn (SON) positive anomalies (e.g. early 18th century). However, continuous, decadal wet periods seem to correspond in time to both autumn and spring (MAM) positive rainfall anomaly years (e.g. 1570/90, 1830/40, 1870/1900). High frequencies of large floods were registered during the late Medieval Warm Period (AD 950-1200), and during some decades of the Little Ice Age with an average of 0.22 floods/year (1440-1490, 1520-1570, 1600-1740, 1770-1800, 1820-1840, 1870-1900), but flood frequency decreased in the 20th Century (1945-1973; 0.14 floods/year). During wet phases (e.g. late 19th century), large floods occurred during all seasons, whereas a predominantly autumn extreme flooding (>70%) is linked to a rainfall patterns with higher inter-annual variability (e.g. 1945-1973). The recurrence of dry phases is higher since early 17th century, and the frequency of continuous wetter phases lower than the ones with marked annual variability. This results in a trend with less frequent high magnitude catastrophic floods. This study confirms a shift from autumn rainfall maxima towards winter since the early 1990's. The tendency towards longer dry periods and increased inter-annual variability (with 1-3 years maximum wet spells) and a changing seasonal rainfall distribution are thought to be key in modelling projections for this specific arid Mediterranean region. © 2011 Elsevier Ltd.

Documentary climate data describe evidence of past climate arising from predominantly written historical documents such as diaries, chronicles, newspapers, or logbooks. Over the past decades, historians and climatologists have generated numerous document-based time series of local and regional climates. However, a global dataset of documentary climate time series has never been compiled, and documentary data are rarely used in large-scale climate reconstructions. Here, we present the first global multi-variable collection of documentary climate records. The dataset DOCU-CLIM comprises 621 time series (both published and hitherto unpublished) providing information on historical variations in temperature, precipitation, and wind regime. The series are evaluated by formulating proxy forward models (i.e., predicting the documentary observations from climate fields) in an overlapping period. Results show strong correlations, particularly for the temperature-sensitive series. Correlations are somewhat lower for precipitation-sensitive series. Overall, we ascribe considerable potential to documentary records as climate data, especially in regions and seasons not well represented by early instrumental data and palaeoclimate proxies.