Is it right that climate change in the Arctic could shut down the Gulf Stream?
Yes, this is possible. When warm water moves northwards from the tropics to the Atlantic Ocean in the Gulf Stream, it gets denser (and hence, heavier) and sinks. There are two reasons for this: it is cooled by the cold surface air, and gets saltier because the new sea ice is “fresher” than the ocean water. Water is denser the colder and saltier it is. The sinking water is replaced by more warm water from the tropics, and goes back to the tropics as a cold, deep ocean current. This phenomenon is the so-called thermo-haline circulation – also referred to as the “conveyor belt”. The warm current (the Gulf Stream) is the reason why the western European coast enjoys a much warmer climate than expected when looking only at the latitude. Climate change in the Arctic means that the water arriving to the Arctic Ocean is not cooled down as much. At the same time, more fresh water arrives into the ocean as the Greenland glaciers melt and runoff increases from the big Russian and Canadian rivers.
