River deltas in danger: a study in Nature Sustainability warns of the risk of extinction for coastal systems
The prestigious journal Nature Sustainability recently published the study by an international group of experts on coastal environments, including two Italian professors from Unimore (Prof. Vittorio Maselli) and the University of Bologna (Prof. Alessandro Amorosi), which traces the fundamental role that river deltas have played in the socio-economic development of the last 7,000 years and warns of the tragic consequences that the climate crisis could have on the future evolution of these fragile and complex areas.
From the birth of the first city-states in Mesopotamia and along the Nile Delta to the Anthropocene (the last 70 years in which humans have become the primary agent of modification of the Earth's system), the study reveals how the natural growth of delta systems — nourished by river sediments — has accompanied human progress in Asia and the Mediterranean area. Deltas have fostered innovations in water management, subsidence control, and erosion mitigation, creating a profound socio-ecological interdependence between human civilization and the evolution of these environments.
In recent decades, the increasing human pressure and land use in coastal areas, linked to the exponential growth of the population and the development of megacities in many of these regions, has made the deltas increasingly vulnerable, posing a serious threat to their survival.
Global warming has aggravated the crisis of river and delta systems in Italy as well, multiplying on the one hand periods of prolonged drought and intensifying on the other the occurrence of extreme weather events with devastating river floods. Italian deltas, first and foremost the Po Delta, are experiencing a dual effect: on one side, reduced rainfall and rising temperatures decrease the supply of fresh water, with critical consequences for agricultural and urban water availability. On the other side, sea level rise, accelerated by the melting of polar ice caps, and reduced water flows facilitate the intrusion of saltwater wedges into rivers and underground in coastal regions, turning fertile soils into increasingly unproductive saline land, with devastating impacts on agriculture and biodiversity.
The study highlights the crucial challenges that deltas will face in terms of governance, management, and planning, and underscores the importance of new technologies and strategies to address these problems. To ensure sustainable development, the world’s deltas will need to be able to cope with sea-level rise caused by global warming and the reduction of sediment input, which is being trapped upstream by dams. Beyond potential local and temporary solutions, the study stresses that, in the absence of climate stabilization, it will be extremely difficult to preserve delta systems and their associated ecosystems.
In scenarios of extreme sea-level rise (two metres or more over the next two centuries), deltas are at risk of being progressively submerged, making economic development unsustainable and even human presence in these areas impossible. Unless definitive measures are taken immediately to reduce CO₂ emissions and implement effective mitigation strategies to protect delta systems, the future of areas subject to progressive submersion could involve land abandonment and large-scale human migrations to more hospitable regions at higher altitudes. This scenario, which in some deltas like the Mississippi is already becoming an inevitable reality, risks marking the end of the millennial interaction between human societies and delta environments, irreversibly compromising the ecosystem and socio-economic benefits that these areas have historically offered to humanity.
"If we do not intervene immediately to reduce the anthropic activities that disrupt the natural processes of river deltas, their loss could become irreversible, putting the lives of millions of people around the world at risk" commented Prof. Vittorio Maselli, of the Unimore Department of Chemical and Geological Sciences.
Categorie: Notizie_eng, International - english
Articolo pubblicato da: Ufficio Stampa Unimore - ufficiostampa@unimore.it