Arctic ice melt is changing ocean currents

A major ocean current in the Arctic is faster and more turbulent as a result of rapid sea ice melt, according to new research from NASA. The current is part of a delicate Arctic environment that is now flooded with fresh wateran effect that NASA attributes to human-caused climate change.

Using 12 years of satellite data, scientists have measured how this circular current, called the Beaufort Gyre, has precariously balanced an influx of unprecedented amounts of cold, fresh water — a change that could alter the currents in the Atlantic Ocean and cool the climate of Western Europe.

The Beaufort Gyre keeps the polar environment in equilibrium by storing fresh water near the surface of the ocean. Wind blows the gyre in a clockwise direction around the western Arctic Ocean, north of Canada and Alaska, where it naturally collects fresh water from glacial melt, river runoff and precipitation, explains a statement.

This fresh water is important in the Arctic in part because it floats above the warmer, salty water and helps to protect the sea ice from melting, which in turn helps regulate Earth’s climate. The gyre then slowly releases this fresh water into the Atlantic Ocean over a period of decades, allowing the Atlantic Ocean currents to carry it away in small amounts.

Since the 1990s, the gyre has accumulated a large amount of fresh water — 1,920 cubic miles — or almost twice the volume of Lake Michigan. The new study found that the cause of this gain in freshwater concentration is the loss of sea ice in summer and autumn.

Persistent westerly winds have also dragged the current in one direction for over 20 years, increasing the speed and size of the clockwise current and preventing the fresh water from leaving the Arctic Ocean. If the direction were to change, the wind would reverse the current, pulling it counterclockwise and releasing the water it has accumulated all at once.

Image credit: Esther Horvath via Alfred Wegener Institute

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