In the oceans, a well-defined steep vertical gradient of salinity, a change in aquatic salinity with depth. Though this varies with latitude, the halocline is from about 70 to 200-300 metres below the surface. The Arctic halocline could be influenced by fresh water influx from Arctic rivers. A sudden change in the North Atlantic's halocline could, for instance, effect the long-range oceanic currents such as the Gulf Stream; this could, for instance, effect the climate of Northern Europe.