A database on climate change over the last two centuries has been realized thanks to the European project ALP-IMP (Multi-centennial climate variability in the Alps based on Instrumental data, Model simulations and Proxy data), where the group of Historical Climatology of the Institute of Atmospheric and Climatic Sciences (ISAC) of the National Research Council, Bologna, headed by Teresa Nanni, participated for Italy. Research was carried out in collaboration with Maurizio Maugeri of the Institute of Applied General Physics of the University of Milan.
The ALP-IMP project allowed the recovery of the longest historical meteorological data series for a vast European region centered on the Alps (this region is called Greater Alpine Region and extends from 4° to 19° E and from 43° to 49° N) and, with it, all the historical information of the weather stations (metadata). "Among regional climatic databases, this can be considered the most reliable and complete currently available, both concerning the period covered (more than two centuries) and the spatial high resolution of ultrasecular stations. Besides the most commonly studied variables, such as temperature and precipitation, the database also includes atmospheric pressure, cloud coverage, times of daily sunshine, relative damp and partial vapor pressure."
ALP-IMP has therefore enabled the realization of a database of around 250 stations, over 50 of which Italian, distributed on a vast European region that includes all Northern Italy and part of Central Italy. A detailed description of the database recovery work has been published in the January issue of the International Journal of Climatology.
The great improvement in availability, quality, reliability and homogeneity of the obtained secular historical series gives the data the necessary credit to depart from the current uncertainty, where results often substantially vary from research group to research group that use data of different origin and reliability.
The results of the data analysis, still preliminary, show excellent agreement for temperature with those obtained for Italy and published by our research group last year in the same international journal. The tendency is toward an increase in temperatures that, over the last century, is 1.2°C (with small variations according to the region under examination). This tendency is accompanied by a clear increase in the atmospheric pressure (on average 1.1 hPas - hecto Pascal, equivalent to 1.1 millibars, in the last century). The precipitations have a less uniform pattern, with negative tendencies, i.e. a decrease (albeit very weak) south of the Alps and positive, i.e. an increase in some northern regions of the Alps (particularly the northwest). Equally inhomogeneous has been the course of the cloud coverage and hours of daily sunshine. Instead, the course of partial vapor pressure (indicative of the content of water vapor in the atmosphere) is clearer, on the increase, and the relative damp, in decline, in perfect agreement with the general picture.
More detailed analyses are still in progress.