The weather behind the words. New methodologies for integrated hydrometeorological reconstruction through documentary sources

Abstract. The historical climatology has remarkable potentialities to produce climatic reconstructions with high temporal resolution. However, there are methodological limitations that hinder the spatial development of this discipline. This study presents a new approach to Historical Climatology that overcomes some of the limitations of classical approaches such as the Rogations Method or the Content Analysis: the Cost Opportunity for Small Towns (COST). It analyses historical documents and takes advantage of all sort of meteorological information available in the written documents, not only the most severe events, thereby overcoming the most prominent bottleneck of former approaches. COST relies on the fact that the use paper had a high cost, so its use to describe meteorological conditions is hypothesized to be proportional to the impact they had on society. To prove the validity of this approach to reconstruct climate conditions, this article uses exemplarily the Municipal Chapter Acts of a small town in Southern Spain (Caravaca de la Cruz), which span the period 1600–1900, and allow to obtain reconstructions with monthly resolution. Using the same documentary source, the three approaches have been used to derive respective climate reconstructions, which are then compared to assess the consistency of the climate signal and identify possible caveats in the methods. The three approaches lead to generally coherent series of secular variability in the hydrological conditions and that agree well with the results pointed out by previous studies. Still, COST approach is arguably more objective and less affected by changes in the societal behavior, which allows it to perform comparative studies in regions with different languages and traditions.