Note that there is
also poleward transport in the shallow currents at the western edge of each subtropical ocean gyre - known as western boundary currents.
[Response: The classical (i.e. Stommel) theory of the subtropical gyre requires that the interior equatorward (Sverdrup) transport that takes place everywhere but a narrow strip along the western edge of the basin, precisely balance
the poleward transport that takes place in a narrow boundary current along the western edge of the basin.
A decrease of between 8 - 33 % is seen in
the poleward transport of heat at the doubling of CO2.
Although more research is needed, there is some agreement among oceanographers that, for the entire area north of 30 N latitude, the ocean's
poleward transport of heat is the equivalent of about 15 watts per square metre of the earth's surface (W / m2).
The vertical transfer of energy is directly proportional to
the poleward transport or advection of heat.
Model simulations of the atmosphere also indicate an increase in
the poleward transport of latent heat as precipitation, mainly at tropical latitudes (Haywood et al., 2009).
Model experiments suggest that a 15 % increase in
the poleward transport of sensible heat by ocean circulation is sufficient to explain the reduced latitudinal gradient in sea surface temperatures (SSTs) observed during the Pliocene (Dowsett et al., 1992).