There is still debate over what kind of ocean circulation change causes the change in heat transport. (realclimate.org)
In other words, there is general warming occurring at the same time ocean circulation changes to accelerate the general warming. (realclimate.org)
This thesis presents the results of several general circulation model simulations aimed at studying the effect of ocean circulation changes when they occur in conjunction with increased atmospheric trace gas concentrations. (pubs.giss.nasa.gov)