Level exceeds ‘Cascais1938’ benchmark by 23.3 cms
The mean sea level (MSL) measured at the Cascais tide gauge recorded “the highest level ever” in 2024 – 23.3 centimetres above the ‘Cascais1938’ benchmark, Carlos Antunes, from the Faculty of Sciences at the University of Lisbon, revealed today.
In a statement coming just as the government has announced a raft of measures to shore up the nation’s coastline, the geographer said that this reading surpassed “the second highest MSL level of 23.2 centimetres (cm) recorded in 2022”.
A tide gauge records and measures the ebb and flow of the tides, with the ‘Cascais1938’ benchmark “corresponding to the average sea level between 1882-1938” and used as a base level for measuring altitudes.
Carlos Antunes says that “the rate of rise of the MSL in Cascais, when compared with satellite altimetry data, shows figures and trends similar to those of the global MSL rate”, indicating that in the last three years the average sea level “has been above 20 cm, something that had only happened occasionally in 2010, an exceptional year due to the sequence of storms”.
According to the Geodesy and Hydrography expert, in addition to the thermal expansion of the oceans and the melting of glaciers, “the recent high temperature conditions in the North Atlantic may have exceptionally contributed to this sharp rise between 2022 and 2024.
“In the last 25 years, the Cascais tide gauge has seen a rise of 9.7 cm, corresponding to an average rate of four millimetres per year,” he said, adding that an analysis of the time series of the sea level record shows that “the MSL on the Portuguese coast, as on a global level, is rising,” increasing continuously “in the order of 0.9 mm/year per decade.”
Lusa
