  The present study investigates how global thermodynamic properties of the
climate system are affected by the changes in the intensity of the imposed
oceanic heat transport in an atmospheric general circulation model in
aqua-planet configuration. Increasing the poleward oceanic heat transport
results in an overall increase in the surface temperature and a decrease in the
equator-to-pole surface temperature difference as a result of the ice-albedo
feedback. Following the classical ansatz by Stone, the atmospheric heat
transport changes in such a way that the total poleward heat transport remains
almost unchanged. We also find that the efficiency of the climate machine, the
intensity of the Lorenz energy cycle and the material entropy production of the
system decline with increased oceanic heat transport which suggests that the
climate system becomes less efficient and turns into a state of reduced entropy
production, as the enhanced oceanic transport performs a stronger large-scale
mixing between geophysical fluids with different temperature, thus reducing the
availability in the climate system and bringing it closer to a state of thermal
equilibrium.
