# Assessment of the Impacts of Climate Change on Power Systems: The Italian Case Study
## 1 Introduction  
The world is facing enormous environmental issues. The rate of energy consumption that we are accustomed to has begun to stress the Earth's resources and its ability to sustain our current lifestyle. In this context of threatened sustainability, the urgency to deploy solutions to contrast climate change is compounded by parallel and equally daunting issues, such as the depletion of conventional energy supplies and the safety and political stability of several energy-producing countries. According to the World Meteorological Organization (WMO), climate is defined as an average weather. The climate system is an interactive system with five components: the atmosphere, the hydrosphere, the cryosphere, the biosphere and the land surface; and these five components are affected by external inputs such as the Sun and human activities [1]. The climate is the state of the climate system, which is a measure of relevant meteorological variables over a given period of time--which the WMO sets at 30 years [2]. Therefore, climate change is defined as a statistically significant variation from its mean state, or in its variability. The most recent (August 2021) AR6 of the IPCC WG I [3] reported the influence of human activities on climate change as an \"unequivocal\" cause. In addition, five new illustrative emissions scenarios were included in AR6, compared with AR5. One of the most concerning human activities responsible for altering the climate system is power production. In 2021 the global energy-related CO\({}_{2}\) emissions were equal to 33.0 Gt [4]. Despite these figures, the world continues to electrify, with an all-time high request for power supply. However, according to the \"Evolving Transaction\" scenario, i.e., a scenario in which government policies, technology, and societal preferences continue to evolve ina manner and at a rate that has been observed in the recent past [5], a slowing down of forecast rates is predicted. From the point of view of the \"Evolving Transaction\" scenario, the following remarks are of greatest relevance [5]:  
* About three-quarters of the total primary energy growth will be used for electricity generation, with about half of the total primary energy absorbed by the electricity sector by 2040;
* Almost all of the growth in electricity demand comes from developing economies, led by China and India, if compared with OECD countries, reflecting both slower economic growth and the weaker responsiveness of electricity demand to economic growth in more mature, developed economies;
* The mix of fuels in global electricity generation is shifting significantly, with renewable energy sources (RES) gaining share at the expense of coal, nuclear and hydro. The share of natural gas remains largely unchanged at around 20%. In the future, two-thirds of the increase in electricity generation will come from RES, with their share of the global electricity sector rising to about 30%. In contrast, the share of coal is declining/will decline significantly, and by 2040 it will be overtaken by renewables as the main energy source in the global power sector. The worldwide electricity generation from renewable energy sources, over the last twenty years, is characterized by (data available in 2021, referring to 2019): hydropower generation equal to 4321 GWh; wind power generation of 1412 GWh (one third of hydropower); PV generation equal to 693 GWh. These data are justified by the high-capacity factor of hydroelectric plants (3653 h per year (h/y) on average), photovoltaic (1241 h/y in 2019) and wind (2199 h/y) [6]. The hydroelectric sector still dominates the RES industry, however, with an increasing presence of wind and PV in the power generation mix. Looking at RES generation capacity worldwide, in 2020 hydropower capacity was equal to 1331.9 GW (of which 222.5 GW in Europe), wind power capacity amounted to 733.3 GW (207.8 GW in Europe) and solar power capacity was equal to 714 GW (163.5 GW in Europe) [7]. It is worth noticing how the latter two capacities combined (viz.