Keeping a cool head at a time of global warming

30th March 2009

Luca Mercalli

President of the Italian Meteorological Society

Biography

Luca Mercalli, (Turin, 1966), climatologist, President of the Italian Meteorological Society (SMI - established in 1865), and editor of the Nimbus Journal. His research activities deals with of Alps climate history, analysis of time series of meteorological data and glaciers observation. He has written more than one hundred scientific publication, seven books (among which the Climatic atlas of Valle d'Aosta – Italy – 2003, Climates, waters and glaciers between Gran Paradiso and Canavese (2006) The climate of Turin since 1753 – 2008) written with his staff. He is involved in formation and communication activities with more than 800 conferences in Italy and abroad, 1000 scientific articles, most of which on “La Repubblica”, and participation at television shows (RAI3 Che tempo che fa e RAI2 TG Montagne). For Rizzoli he published “Clouds Philosophy”.

Abstract

If the time scale of meteorology is in the order of days, the frame of reference of climatology is in terms of millions of years. The reconstruction of the paleoclimate depends on the methods of palynology, glaciology, geochemistry, but in general – with the exception of dendrochronology – they do not yield very accurate temporal resolutions or a rigorously quantitative restitution of physical quantities. The historical series of data measured by instruments yields more reliable data for the last three centuries, and are exceptionally helpful for the calibration of proxy-data and of dynamic models. The Turin series, begun in 1753 for temperature, in 1787 for snow and in 1802 for rain is one of the longest and comprehensive that has ever existed. Through its reconstruction – from the details of ancient instruments to the transfers of the observatory – it is possible to examine issues such as statistical quality, measurement errors and the necessity for homogenisation over the long period. Having reduced noise, including noise from the urban heat island, the evolutionary signals of the various parameters were obtained; from which emerges the net thermal increase that has occurred over recent decades, confirmed also by the retreat of the nearby Alpine glaciers.