These models are lacking in oceanography. Ocean water circulation is driven partly by the world turning vans mostly by temperature/salinity density gradients, heavier water bodies beneath less dense. Thermohaline circulation accelerates when there is more open water in the Arctic Ocean. In September there is more sea ice formation (frozen fresh water) and more sinking of very salty cold water. This more Arctic Water entering the Atlantic, greater meanders to the Gulf Stream dissipating more energy, warmer water passing Svalbard and more warmer midwater in the Arctic increasing the summer sea ice melt.