Reasons for a fresher northern North Atlantic in the late 20th century

Observational analyses suggest that the northern North Atlantic is fresher in the late 20th century in comparison to the 1950 - 60s. Here we examine possible contributors to these observed changes by analyzing a four-member ensemble of 20th century simulations from a coupled climate model. Results show that a weaker meridional freshwater divergence related to a weaker thermohaline circulation in the North Atlantic is the primary cause for the freshening in the northern North Atlantic in the model. The increased P-E tends to enforce it, but the reduced sea ice flux into this region tends to weaken it.