Future droughts in northern Italy: high-resolution projections using EURO-CORDEX and MED-CORDEX ensembles

Abstract

We analyse the expected characteristics of drought events in northern Italy for baseline (1971–2000), near (2021–2050), and far (2071–2100) future conditions, estimating the drought spatial extent and duration, the percentage of affected area, and the frequency of drought episodes. To this end, daily ensembles of precipitation and temperature records from Global Climate Models (GCMs) and Regional Climate Models (RCMs) pairs, extracted from EURO-CORDEX and MED-CORDEX for the RCP 4.5 and 8.5 scenarios, are collected at spatial resolution of 0.11 degrees. Before the analysis, model outputs are validated on daily weather station time series, and scaling factors for possible use in bias correction are identified. Annual temperature and precipitation anomalies for near and far future conditions are investigated; drought events are identified by the standardized precipitation evapotranspiration index and standardized precipitation index at the 12-, 24-, and 36-month timescales. This study highlights the importance of using multiple drought indicators in the detection of drought events, since the comparison reveals that evapotranspiration anomaly is the main triggering factor. For both scenarios, the results indicate an intensification of droughts in northern Italy for the period 2071–2100, with the Alpine chain being especially affected by an increase of drought severity. A North-to-South spatial gradient of drought duration is also observed.

Vegetation response to droughts: The case of northern Italy

“…After 2003, drought events became frequent and in the years 2004, 2005, 2006, 2007, 2012, 2014 and 2020, at least a summer drought event was observed. In their studies, Hoerling et al (2012) and Gudmundsson and Seneviratne (2015) concluded that the whole Mediterranean Basin experienced an intensification of droughts in the last two decades, and an increase in terms of magnitude and spatial distribution is expected from the work by Baronetti et al (2022). This could be related to the migration of the North Atlantic Oscillation to more northerly regions (200–300 hPa) that took place in recent years.…”

“…[Colour figure can be viewed at wileyonlinelibrary.com] central and southern Italy, however, where significant effort was spent owing to the strong precipitation reduction during the last 50 years (e.g., Sirangelo et al, 2017), only few studies explored drought characteristics and trends in northern Italy (Baronetti et al, 2020;Marchina et al, 2017). On the other hand, although northern Italy is traditionally rich in water resources, in recent years, the severity of drought events increased and it is expected to worsen in the near future (Baronetti et al, 2022). It is thus important to understand what impact such increasing drought severity can have on the ecosystems and vegetation communities of this area.…”

“…et al (2015). This tendency is expected to continue until the end of the century, and a positive temperature anomaly of 4 C under the RCP 8.5 is estimated by Baronetti et al (2022). In the Po Valley, where the strongest vegetation response to drought was observed, the NDVI-LST relationship is weak (low R 2 ).…”

“…In the Mediterranean Basin, owing to the large interannual variability of precipitation, climatic droughts are quite common (Lionello, 2012). The spatial and temporal complexity of Mediterranean droughts is discussed in several studies (González‐Hidalgo et al, 2018; Vicente‐Serrano et al, 2012) and a significant increase of drought events was identified both in current data (Baronetti et al, 2020; Vicente‐Serrano et al, 2014) and in the projections for the coming decades (Baronetti et al, 2022; IPCC, 2022; Tramblay et al, 2020). Droughts in the Mediterranean basin imply loss of crop yield (Schillinger et al, 2008), increase of forest fires (Turco et al, 2018), vegetation degradation (Rodrigo Comino, 2022) and desertification (Halbac‐Cotoara‐Zamfir et al, 2020).…”

Unprecedented snow-drought conditions in the Italian Alps during the early 2020s

“…In the last two decades, different areas of Europe have been affected by numerous severe, large-scale drought events (in 2003, 2007, 2011, 2012, 2015, 2017, 2018, 2019, and 2020Blauhut et al 2022). In particular, the Mediterranean area has shown the highest drought frequency and severity since the early 1990s (Spinoni et al 2015, Romano et al 2022 and droughts are projected to become even more recurrent and intense (Spinoni et al 2018, Baronetti et al 2022), with profound economic consequences (Naumann et al 2021). Although mainly investigated in the United States, recent global research showed that, in the last few decades, the frequency and duration of snow droughts have increased in Europe, which emerged as a hotspot for this kind of drought (Huning and AghaKouchak 2020).…”