With a study that correlated the climate projections for the next few years with those of the movements of the earth's surface along some Mediterranean coasts in the last 20 years, the researchers highlighted a certain increase in sea level, hypothesizing two possible scenarios.
The theme of climatic variations is increasingly focusing the attention of researchers in all sectors of the geosciences. With the study "Natural Variability and Vertical Land Motion Contributions in the Mediterranean Sea-Level Records over the Last Two Centuries and Projections for 2100", published in recent days in the MDPI journal Water, researchers from the National Institute of Geophysics and Volcanology (INGV ), Radboud University (Holland) and Sorbonne Université (France) observed how sea level could increase in 2050 and 2100 at nine tide gauge stations located in the central-northern Mediterranean, which measure the level starting from 1888.
The calculation included the effects of subsidence (vertical downward movement of the ground due to natural or anthropic causes) identified by GPS geodetic measurements acquired over the last 20 years or so and the natural fluctuation of the sea level, caused by climate variability, which acts with periods decennial.
The study predicted two possible sea level scenarios in 2050 and 2100, calculated on the basis of climate projections provided by the Intergovernmental Panel on Climate Change (IPCC, the United Nations body for evaluating the science of climate change), refined with the data of the subsidence, which varies from place to place, and of the natural fluctuation of the sea level.
“The results show that in the RCP8.5 climate scenario, a maximum increase in mean sea level of about 2050 cm could occur by 20, while in 2100 it could reach about 57 cm. In the RCP2.6 scenario, which is less critical than the previous one, in 2050 there could be an increase of 17 cm and in 2100 of 34 cm", highlights Marco Anzidei, researcher at INGV, co-author of the study and coordinator of the European project SAVEMEDCOASTS (www. savemedcoasts.eu) which funded the research.
Antonio Vecchio - author of the study and researcher at Radboud University - also points out that "at the local level, sea level fluctuations can contribute up to 9% of the total expected variation, while subsidence and variability together are responsible for around 15% % of sea level change. In the Venice lagoon, where subsidence accelerates the effect of sea level rise, it is estimated that in 2100 the mean sea level will be between 60 and 82 cm higher than today, in the two climate scenarios RCP2.6 and RCP8.5”.
Analyzes show that local effects play a relevant role in calculating sea level rise projections for different areas. “In particular” - concludes Marco Anzidei - “along the low and subsiding coasts the expected increases are able to cause a more rapid marine entry, i.e. the sea tends to submerge more or less large stretches of coast more quickly than in not subsiders. This represents a risk factor for the environment, for infrastructures and for human activities, such as erosion and the increased risk associated with floods, storm surges and tsunamis, with the consequent economic losses. Institutions, at all levels of governance, must take these projections into account because they are essential for dealing with the management of our coasts in a more informed way".
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Photo - The Venetian lagoon. Here, according to the most critical projections (RCP 8.5) in 2100 the mean sea level could be about 82 cm higher than today. Ph © Marco Anzidei