Increasing Freshwater Runoff in Arctic Could Alter Gulf Stream
08.04.2011 - Water & Oceans, Arctic
A massive pool of fresh water that has formed in the Arctic Ocean as a consequence of increased freshwater runoff from Siberian and Canadian rivers (which is coming from melting glaciers and melting sea ice) could spill into the Atlantic and alter the Gulf Stream, scientists say. Should this happen it could upset the Thermohaline Circulation (THC) and slow the Gulf Stream, which brings warm tropical waters towards Europe and gives it its relatively mild climate.
So far wind patterns have kept the cold freshwater runoff bottled up in the Arctic. The wind patterns, normally shift their direction at intervals of five to ten years; the winds haven’t shifted their pattern for the unusually long time of twelve years.
Driven by differences in salt content and wind patterns, the Thermohaline Circulation loops like a conveyer belt from the tropics to the North Atlantic. As it progresses northward, the warm water from the south becomes more saline and grows denser as it cools. In the North Atlantic, at deepwater formation points, cold air cools the water and it sinks, before it warms again and rises as it makes its way south. This cycle could be affected when the pool of icy freshwater makes its way into the Atlantic.
Researchers from the Alfred Wegener Institute (AWI) in Germany found that the Arctic's fresh water content has increased 20% since the 1990s, which amounts to an additional 8,400km³ of freshwater in the Arctic Basin. The consequences on European climate would be dramatic. In past studies, the scientists have identified fresh water build-up in the Canada Basin; however in the past three years, they have noticed changes on the Eurasian side of the Arctic Ocean.
