When we picture the effects of melting glaciers, many of us think of rising seas and retreating ice streams. But along Greenland’s coastline, a quieter transformation is underway, one that is affecting how the ocean breathes and how it reacts to and buffers itself against change. In Young Sound, a fjord carved into Greenland’s remote northeastern coast, decades of monitoring have revealed that glacial meltwater does not simply dilute the salt in seawater.