Climate change in the mediterranean area and in Sicily: time series analysis of temperature and precipitation using wavelet

The climate of a place is often defined in a very restrictive sense, such as the average weather conditions of a given location. A definition of the term in a broader meaning is as follows: “state of the climate system” where the term state means the statistical description in terms of mean value and variance of the most important meteorological parameters, such as temperature, precipitation, distribution of winds, etc.. in a sufficiently long timeframe and in any case not less than 30 years. From this point of view, we can say with certainty that the Earth's climate has never been constant, but over the time has undergone to various changes due to natural factors. Mainly in the 80s started a strong dispute over the anthropogenic nature of climate change that has involved both the scientific and the political world globally. Starting from that period, in fact, a long sequence of years characterized by average temperatures record has induced the scientific community to investigate the nature and causes of such global warming. Today, despite the understanding on the origin and evolution of global warming has greatly improved, the climate change thematic remains one of the most debated among the entire international scientific community. As matter of fact, the chaotic nature of the atmosphere and the complexity of the Earth's climate system make the issue far from being resolved. The work dealt with in this doctoral thesis is placed in such context and aims to provide a historical framework to the science of climate change (Chapter 1) to subsequently pass on to the description of both natural and anthropogenic climate changes scientifically most credited causes (Chapter 2). The next chapter will provide an overview of climate models currently used globally, their development over the last 20 years and the climate scenarios envisaged, both globally and regionally, by the end of the century. Chapter 4 depicts the analysis and description of the main climatic changes observed and the future scenarios envisaged by the models for the Mediterranean area. In Chapter 5 the main mathematical tools for time series analysis are described and finally, in Chapter 6, the Wavelet analysis technique to some historical series of temperatures and precipitation observed on some locations of Sicily.