Will deep water formation collapse in the North Western Mediterranean
Sea by the end of the 21st century?
Deep water formation (DWF) in the North Western Mediterranean (NWMed) is
a key feature of Mediterranean overturning circulation. Changes in DWF
under global warming may have an impact on the regional and even on the
global climate. Here we analyze the deep convection in the Gulf of Lions
(GoL) in a changing climate using an atmosphere-ocean regional coupled
model with a high horizontal resolution enough to represent DWF. We find
that under the RCP8.5 scenario the NWMed DWF collapses by 2040-2050,
leading to almost a 90% shoaling in the winter mixed layer depth by the
end of the century. The collapse is mainly related to changes in sea
water temperature and salinity of Modified Atlantic Water (MAW) and
Levantine Intermediate Water (LIW) that strengthen the vertical
stratification in the GoL. The stratification changes also alter the
Mediterranean overturning circulation and the water, heat and salinity
exchange with the Atlantic.