Paleo proxy data and previous modeling studies both indicate that the massive discharge of icebergs into the North Atlantic may have led to a (nearly) collapsed Atlantic Meridional overturning circulation (AMOC), resulting in a seesaw like climate change between the North Pacific and North Atlantic, such as a warming in the former and a cooling in the latter. Here by using a fully coupled climate model, we show that this Pacific-Atlantic seesaw associated to changes of the AMOC can only occur when the Bering Strait is closed. This closed Bering Strait cuts off the oceanic communication between the North Pacific and Atlantic via this strait. When the AMOC is weakened or collapsed with this closed Bering Strait, the Pacific MOC builds up and transports more warm and salty subtropical water into the North Pacific, leading to a seesaw-like climate changes in these two ocean basins.