You probably know that the world’s oceans contribute significantly to the global climate. Water circulation in the North Atlantic is driven by small differences in water density. These density differences depend on a balance between water temperature and the salinity fluctuations that arise from small freshwater inputs;
i.e. precipitation and river run-off. The circulation process itself is known as thermohaline circulation, or ocean overturn.

Here’s how it works:
The warm, salty, surface waters of the Gulf Stream move up the eastern coast of North America and then east to the European coast. From here, the heat absorbed by the water at the equator is released and carried into Europe by westerly onshore winds. As the surface water cools, it becomes denser and sinks to a depth of about 1 mile, traveling back across the Atlantic and then southward toward the equator again. The climates of Europe and North America rely heavily on the heat released from the Gulf Stream.

New Revelations:
Over the past 30 years, the North Atlantic has been receiving huge inflows of cold freshwater. There is mounting evidence that the resulting cool-down of the North Atlantic could give rise to a mini ice age. Scientists cannot say without a doubt that these huge inflows come from the glaciers melting in the Arctic, but they are certainly the prime suspect.

The new mass of relatively fresh water sits on top of the ocean’s saltier water like a thermal blanket. This may cause a weakening or even halting water circulation. As glaciers continue to melt and precipitation in higher latitudes increases, greater inflows of cold freshwater are going to rapidly drop salinity and temperatures of the North Atlantic and adjoining seas.

This could have a profound effect. The deepwater current that twists and swirls through all the world’s oceans is driven primarily by the circulation of the North Atlantic. If the North Atlantic circulation pattern were altered, average temperatures over much of the U.S. could drop by 5 degrees Fahrenheit and by as much as 10 degrees Fahrenheit in northern Europe and northern Asia. Strangely enough, global warming could lead to localized cooling.

Travis Hill