The AMOC is a system of Atlantic Ocean currents, including the Gulf Stream ... "The reason we're not sure about the AMOC weakening is that all these different fingerprints can give us different ...
there can be strong warm currents towards higher latitudes as the oceans are bounded by continents on each side. The Southern Ocean is different as there is no land mass connecting to Antarctica.
By matching up the shells from clams of different ages ... the AMOC and Arctic waters, where ocean conditions are heavily dependent on the strength of currents flowing from the south.