Fingerprint of climate change in precipitation aggressiveness across the central Mediterranean (Italian) area

Abstract

Rainfall erosivity and its derivative, erosivity density (ED, i.e., the erosivity per unit of rain), is a main driver of considerable environmental damages and economic losses worldwide. This study is the first to investigate the interannual variability, and return periods, of both rainfall erosivity and ED over the Mediterranean for the period 1680–2019. By capturing the relationship between seasonal rainfall, its variability, and recorded hydrological extremes in documentary data consistent with a sample (1981–2015) of detailed Revised Universal Soil Loss Erosion-based data, we show a noticeable decreasing trend of rainfall erosivity since about 1838. However, the 30-year return period of ED values indicates a positive long-term trend, in tandem with the resurgence of very wet days (> 95th percentile) and the erosive activity of rains during the past two decades. A possible fingerprint of recent warming is the occurrence of prolonged wet spells in apparently more erratic and unexpected ways.

Reconstruction of erosivity density in northwest Italy since 1701

“…Since geographical locations have characteristics that require specific model structures and local optimization, then the application of the model over other regions may be limited by the ability to provide representative drivers and parameter values. However, our results suggest that the parsimonious principle used in this study is sufficiently robust and may be suitable for a spatial generalization over the Mediterranean region, whose climate is dominated by Atlantic influences (Diodato et al 2020a).…”

“…Long-term reconstructions of rainfall erosivity can help to disentangle the role of anthropogenic climate change and the natural variability of the climate system in heavy rainfall events and floods (Diodato et al 2020a(Diodato et al , 2020b. The latter, through atmospheric-oceanic teleconnection patterns such as El Niño Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO), can drive the frequency and intensity of regional rainfall events worldwide (Wetter et al 2011, Willems 2013, Gómara et al 2018, Diakhaté et al 2019).…”

A millennium-long climate history of erosive storms across the Tiber River Basin, Italy, from 725 to 2019 CE

“…Furthermore, the high spatio-temporal variability of rainfall regimes due to topography and the presence of sea masses make it difficult to establish the actual role played by the NAO on erosive precipitation in southern Europe 103 , especially when wide areas are considered and long-term time-series (i.e. over a millennium) are not available 43 . We thus highlight the need to understand in more detail the links between large-scale atmospheric and oceanic variability and rainfall erosivity, which depend on the geographical context (e.g.…”

Climate Patterns in the World’s Longest History of Storm-Erosivity: The Arno River Basin, Italy, 1000–2019 CE

“…Casanueva et al (2014) examined several Northern Hemisphere teleconnection patterns and found an increase in extreme precipitation events in the central and eastern Mediterranean regions with positive summer values of the NAO index for the period 1950-2010. In a multi-centennial perspective (1680-2019 CE), Diodato et al (2020a) showed that substantially neutral (winter) NAO states (without a clear dominance of positive or negative phases) correspond to a decline of erosivity extremes throughout the Mediterranean. In the present basin-wide study, we observed (Figure 7E) a predominantly weak anticorrelation between the reconstructed erosivity time-series and the proxy-based multi-annual NAO reconstruction of Hernández et al (2020).…”