Why the 2022 Po River drought is the worst in the past two centuries

Abstract

The causes of recent hydrological droughts and their future evolution under a changing climate are still poorly understood. Banking on a 216-year river flow time series at the Po River outlet, we show that the 2022 hydrological drought is the worst event (30% lower than the second worst, with a six-century return period), part of an increasing trend in severe drought occurrence. The decline in summer river flows (−4.14 cubic meters per second per year), which is more relevant than the precipitation decline, is attributed to a combination of changes in the precipitation regime, resulting in a decline of snow fraction (−0.6% per year) and snowmelt (−0.18 millimeters per day per year), and to increasing evaporation rate (+0.013 cubic kilometers per year) and irrigated areas (100% increment from 1900). Our study presents a compelling case where the hydrological impact of climate change is exacerbated by local changes in hydrologic seasonality and water use.

Remote sensing assessment of anthropogenic and climate variation effects on river channel morphology and vegetation: Impact of dry periods on a European piedmont river

“…Previous analysis of long‐term time series of discharge along the Po River pointed out flood peaks in autumn and spring, generated by rainfall and snowmelt events, respectively (Montanari, 2012; Zanchettin et al, 2008), while low discharges are normally observed in February and July (Baruffi et al, 2012), even if changes are expected in the future due to climate change (Montanari et al, 2023; Vezzoli et al, 2015).…”

“…On the other part, the 30‐year average rain precipitation in Italy appears to be almost the same as for the entire period, equal to about 970 mm/year, while evapotranspiration has risen by 10 mm/year in Italy in the last 30 years, with a current average of about 490 mm over the entire period. These trends, which are very likely to be associated with global warming, indicate an augmented risk of extreme drought (Montanari et al, 2023), with the consequent land and sandy bars development and vegetation colonization within the channel of the Po River, especially during the summer period.…”

Targeting farmers’ heterogeneity to enrich climate change adaptation policy design: findings from northern Italy

“…The latest data from Coldiretti, Italy's main agricultural organization, shows that the extreme event resulted in $ 6 billion in damage to agricultural production (Coldiretti 2022). The 2022 event was not an anomaly, but rather a part of a larger pattern of increasingly frequent and intense droughts in the area (Montanari et al 2023). For the authors, this event could undergo a process of 'mediterranization' of the northern river patterns, where the rivers might become more intermittent, experiencing periods of dryness lasting several months (Levantesi 2022).…”

Interannual Variation in the Zooplankton Community of the North Adriatic Sea under Short-Term Climatic Anomalies

“…At the start of 2022, seven months of scarce precipitation led to a reduction in rain and snowmelt, causing a decrease in river flow that was 30% higher than the previous record (Figure 1). This severe and prolonged drought in Northern Italy sparked serious concerns over the socioeconomic impact on agriculture, industry, and energy production [26]. This year was also extremely hot, being the second warmest for Europe and 0.85 • C above the average for the 1991-2020 reference period.…”