published on 9 November 2018 in ecosystems
Dunes and beaches threatened by the increase in CO2
Rising CO2 in the atmosphere may threaten the state of dunes and beaches, increasing the effect of coastal erosion and the risk of flooding. These were the findings of new research coordinated by the Italian National Research Council Institute for the study of Anthropic impacts and Sustainability in the marine environment (CNR-IAS) in Oristano, conducted in collaboration with the Ca’ Foscari University in Venice. The research, published in the Climatic Change journal, analyses the chain of effects on the marine environment triggered by increased CO2, estimating that, from now until 2100, accumulation of sediments on which Mediterranean dune systems are based may decrease by 31%, causing erosion of beaches and greater risk of flooding.
It is known that when carbon emissions increase, the amount of CO2 absorbed by seas and oceans also increase and, as a consequence, the pH decreases. Increased acidification of the seas and oceans would therefore have direct effects on biological cycles that use calcium carbonate. According to the research, the carbonate sediments that make up a large part of the dune-beach systems (such as, for example, the underwater pastures of Posidonia oceanica) could be dissolved by the increasing acidity of the seas. Acidification of seas and oceans may therefore seriously upset the sedimentary balance, since it may to a large extent condition the abundance of organisms, the remains of which create much of the sediment that forms the beach-dune system. Some beaches may change from environments that are progressively growing or stable, into environments that are subject to erosion. Additionally, the research shows how the effect of acidification on the beach-dune system, combined with the forecast rise in the sea level, may increase both coastline retreat, and the negative effects of flooding.