This is very interesting. I always expected that a slowdown of the Meridional Overturning Circulation would lead to higher globally averaged temperatures. Even though most northern hemisphere centric analyses showed a regional cooling (especially in Europe!). I had spent more time considering carbon cycle feedbacks and atmospheric fraction impacts (due to significantly reduced oceanic carbon sequestration)
http://www.nature.com/ngeo/journal/v6/n2/full/ngeo1680.htmlBut, of course, reduced conveyor current flow yields significantly less upwelling, warmer surface temperatures and a reduced oceanic heat sink. Only a very small shift in the heat absorption budget between ocean and atmosphere will yield significant changes in globally averaged surface temperatures. And more, the rate of change of temperatures.
