Warm Atlantic Waters Melting Sea Ice in Arctic

Warm Atlantic Ocean waters are causing sea ice to melt in the Arctic, further contributing to the disappearance of this land mass, according to new research.

A team at Bangor University has realized that warm water in the Atlantic - originating from the Gulf Stream - is flowing deep into the Arctic Ocean and mixing with its colder waters in a way that's leading to a loss of sea ice extent.

"Our oceans are not made up of one body of water, but contain waters of different temperatures and salinity, lying in different 'layers', so the Arctic Ocean is a bit like a jam sandwich, where the 'bread' is the cold water layers above and below the 'jam,' which is the warm, salty water that enters the Arctic from the Atlantic. Sea-ice floating on the surface of the ocean is insulated from the heat of the Atlantic layer by the 'top slice' of cold polar water," lead author Tom Rippeth explained in a statement.

Until now, studies have focused on how turbulent winds and waves play a role in melting Arctic sea ice, and not so much tidal mixing. Tidal flows around the Arctic Ocean are generally weak, so they were never considered a significant factor in ice melt. But researchers now find that tides are stirring up heat in the Atlantic and bringing it to the Arctic, playing a bigger role than previously thought in sea ice loss.

According to the study, water in the Atlantic is four degrees Celsius (39 degrees Fahrenheit) warmer than the surrounding water - that's the warmest it's been in nearly 2,000 years.

It's normal for this warm water - located between 40 and 200 meters (131-656 feet) below the surface - to slowly diffuse upwards into the cold, fresher water above. However, tides are creating more turbulence over steep sea bed topography, and so are greatly increasing the upward movement of heat in these regions.

"Arctic sea ice is likely to retreat further in coming decades, and if it does, interactions between the wind and ocean currents may strengthen. These mixing hotspots may then grow into other areas of the Arctic Ocean with steep sea bed slopes, resulting in further sea-ice retreat," added Sheldon Bacon, from the National Oceanography Centre.

It is said that Arctic sea ice may completely disappear in our lifetime, and with tidal currents stirring things up, this fear may soon become a reality.

The findings were published in the journal Nature Geoscience.

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