Antarctica: Melting ice causes collapse of ocean currents



by LORENZO CIOTTI

Antarctica: Melting ice causes collapse of ocean currents

The deep ocean circulation forming around Antarctica could be doomed to collapse, according to a new study published in Nature. Melting ice in Antarctica is not only raising sea levels, it is also slowing the circulation of deep ocean water with vast implications for global climate and marine life.

Currents carry heat, oxygen, carbon and nutrients around the world. Models show that if global carbon emissions continue at their current rate, melting ice around Antarctica would make nearby ocean waters cooler and less dense.

Professor Matt England exolained: "The resulting subsurface warming in the Amundsen - Bellingshausen seas is of particular concern. This would lead to amplifying feedback with further ice shelf melting and sea level rise." After nearly a year of simulations and analysis, it has been found that including impending meltwater changes around Antarctica, deep ocean circulation decreases by more than 40% by 2050.

This is driven by a reduction in surface water density around the Antarctic margin, which in turn sees increased intrusion of warm circumpolar deep water onto the shelf. Knowledge of surface ocean currents is essential to reducing shipping costs, as traveling without them reduces fuel costs.

In the age of wind-powered sails, knowledge of ocean currents was even more essential. A good example is the Agulhas Current, which for a long time prevented Portuguese sailors from reaching India. Even today, users of sailing boats all over the world profitably use surface currents to maintain speed.

Ocean currents are also very important in the spread of many forms of life. An example is the life cycle of the European eel. Ocean currents are important in the study of marine debris and vice versa. These currents also affect temperatures around the world.

For example, the ocean current that carries warm water from the North Atlantic to northwestern Europe cumulatively and slowly blocks ice along seashores, also preventing ships from entering and leaving inland waterways and seaports, so Ocean currents play a decisive role in influencing the climates of the regions through which they flow.

Cold ocean water currents flowing from polar and sub-polar regions carry with them a lot of plankton, which is crucial for the survival of several key species in marine ecosystems. Since plankton are fish food, abundant fish populations often live where these currents prevail.

Ocean currents can also be used for marine electricity generation, with trials in areas such as those off Japan, Florida and Hawaii.