Some deoxygenation trends in the Mediterranean Sea estimated with the biogeochemical reanalysis of the Copernicus Marine Service and with the high resolution climate projections produced under two different emission scenarios (RCP4.5 and RCP8.5) have been presented at the ECCWO5 Symposium in Bergen (Norway), 17-21 April 2023. The two different analyses have shown a significant reduction of oxygen content in the surface and intermediate layers of the basin driven by the overall warming of the water column, that will become particularly dramatic at the end of the 21st century under the worst-emission scenario (RCP8.5).
In particular, the Mediterranean Sea shows a small but statistically significant deoxygenation trend at surface (-0.05 mmolO2 m-3 y-1) during the last 20 years (i.e., 1999-2019), consistently with the observed increase of surface temperature in the same time period. Moreover, a decrease of approximately 6 (3) % with respect to the beginning of the century has been estimated for the oxygen content of the upper part of the water column in the basin during the 21st century under RCP8.5 (RCP4.5) emission scenario. This dramatic change has been driven by the overall warming of the water column and the increase in the ecosystem respiration.