Temperature Reconstruction for North-Eastern Italy over the Last Millennium: Analysis of Documentary Sources from the Historical Perspective

The past climate reconstruction is of major relevance in order to produce the best climate model projections possible. The study of proxy data contained in ancient documents is one of the most valuable tools available to reach this goal. In the regions where written history had an early and widespread diffusion, it provides precious and long series of information, particularly useful for periods prior to the eighteenth–nineteenth century, when instrumental records did not yet exist. The data sources are different in typology, depending on the historical moment and the geographical area, that is, on the surrounding cultural environment; all of them need to be carefully and critically analysed from a historical point of view, in order to obtain both qualitative and quantitative results. Opportunities and problems concerning the use of documentary data in Italy will be discussed in this article. The results of the current historical study on the winter climate evolution in the Po Valley during the last millennium will be also presented as a case study.