  The global ocean overturning circulation, critically dependent on the global
density stratification, plays a central role in regulating climate evolution.
While it is well-known that the global stratification profile exhibits a strong
dependence to Southern Ocean dynamics and in particular to wind and buoyancy
forcing, we demonstrate here that the stratification is also acutely sensitive
to the mesoscale eddy energy dissipation time-scale. Within the context of a
global ocean circulation model with an energy constrained mesoscale eddy
parameterization, it is shown that modest variations in the eddy energy
dissipation time-scale lead to significant variations in key metrics relating
to ocean circulation, namely the Antarctic Circumpolar Current transport,
Atlantic Meridional Overturning Circulation strength, and global ocean heat
content, over long time-scales. The results highlight a need to constrain
uncertainties associated with eddy energy dissipation for climate model
projections over centennial time-scales, but also for paleoclimate simulations
over millennial time-scales.
