The global energy transition offers new options for mitigation of coastal hypoxia: Do we know enough?

The mitigation of climate change and pollution-related hypoxia and anoxia is a growing challenge for coastal communities. Known ocean conservation measures do not show the desired fast results counteracting deoxygenation. The new infrastructure related to the coastal production of renewable energies linked to the production of green hydrogen can provide new possibilities of artificial ocean reoxygenation to mitigate coastal hypoxia, but has to be treated urgently and seriously from different scientific, engineering and socio-economic angles.

Seasonality of the Meridional Overturning Circulation in the subpolar North Atlantic.

Understanding the variability of the Atlantic Meridional Overturning Circulation is essential for better predictions of our changing climate. Here we present an updated time series (August 2014 to June 2020) from the Overturning in the Subpolar North Atlantic Program. The 6-year time series allows us to observe the seasonality of the subpolar overturning and meridional heat and freshwater transports. The overturning peaks in late spring and reaches a minimum in early winter, with a peak-to-trough range of 9.0 Sv. The overturning seasonal timing can be explained by winter transformation and the export of dense water, modulated by a seasonally varying Ekman transport. Furthermore, over 55% of the total meridional freshwater transport variability can be explained by its seasonality, largely owing to overturning dynamics. Our results provide the first observational analysis of seasonality in the subpolar North Atlantic overturning and highlight its important contribution to the total overturning variability observed to date.