Cambiamenti climatici negli ultimi 2000 anni

Abstract

: Primary aim of the paper is to improve climatic information by recovering and analysing a long time series of written sources. Moreover, climatic changes are related to solar activity in order to verify whether there is an actual relationship of cause-effect as suggested by Eddy (1977). Conclusions are drawn from the analysis of a long series of important climatic changes (i.e., floods of the Po river and its tributaries; floods of the Tiber and Adige rivers; sea flood and freezing of the Venice lagoon; strong winds; storms; hail; heavy rainfall; grasshopper invasions) as follows: i) a worsening of climate during the time period 50CN-1000 AD is not proved because documents are few and incomplete; ii) information on the 10th and 11th centuries are incomplete as well, iii) cooling during the Little Ice Age indicates that the ocean level response to atmospheric temperature variations is not immediate, simple and univocal as models suggest; iv) Earth-Sun relationships can be interpreted only if the various phases are put into the preceding and following whole climatic context. Eddy's theory has to be proved on the basis of the Earth's climatic behaviour in the periods of solar anomaly; collected data suggest that this theory is unreliable: the Spòrer Minimum is rather perturbed, while the Wolf and Maunder ones are not as much. The Spòrer Minimum occurred casually in a period of climatic anomalies; this conclusion is supported also by the observation that such climatic anomalies occurred - in some cases - before the solar ones. Really exceptional phenomena, such as very cold winters, may occur at any time even in periods of very intense atmospheric warming.