AOPP Seminar - The ocean’s centre of mass is sinking signalling rising stratification

We introduce a new way to measure how the ocean’s stratification is changing over time, tracking shifts in its centre of mass. Using a global ocean state estimate from 1992 to 2017, we find that the ocean’s centre of mass has been sinking by about 0.66 cm per decade. This deepening reflects a steady 1% increase in global stratification per decade. The deepening is closely linked to upper-ocean warming, especially in the Indo-Pacific tropics and along major boundary currents, while salinity changes play a smaller role near the poles. Our results show that the ocean’s centre of mass provides a simple, robust global indicator of how warming is reshaping the vertical structure of the ocean.