Ocean currents: The concentrated power of the ocean

Prof. Dr Torsten Kanzow, Head of Climate Sciences Division and Head of the Section Physical Oceanography of Polar Seas at the Alfred Wegener Institute and Professor at the University of Bremen.

Ocean currents

Ocean topography of polar regions

Ocean-ice sheet interaction

Sea level

Ocean currents play various important roles in the climate and in ecosystems in the polar seas. On the one hand they transport large amounts of heat from the mid-latitudes to the Arctic and Antarctic. Once there, this heat can delay the formation of sea ice or cause the floes to melt more rapidly. This applies to the ice covering the Arctic Ocean, as well as to the sea ice in the Southern Ocean, surrounding the continent of Antarctica. On the other hand, ocean currents also transport sea ice and summer meltwater away from the polar regions to the mid-latitudes, where especially the lower-saline meltwater significantly influences the stratification of the ocean’s water masses and their circulation.

But that’s not all: off the coasts of Greenland and Antarctica, the ocean currents come into contact with the outliers of the respective ice sheets. The ice and water mutually affect each other, producing increased melting in marine glaciers and ice shelves alike  – a process that negatively impacts the stability of the inland ice sheets behind them, since the glaciers and ice shelf serve as a brake.

Furthermore, currents in the polar oceans are important because they distribute nutrients and ventilate the global deep sea. The latter occurs when the surface water in large parts of the Arctic and the Southern Ocean cools, causing it to sink; this oxygen-rich bottom or deep water then flows toward the Equator. This so-called overturning of the water masses in the two polar regions makes the Arctic and Southern Oceans key regions in the context of ocean circulation.

At the AWI, we investigate the characteristics and role of ocean currents through interdisciplinary collaborations and active involvement in national and international research networks. We not only pursue basic research, but also consider it our duty to document, analyse, classify and assess climate-related changes in the Arctic and Southern Oceans. Our research is based on oceanographic data, which we gather with the help of autonomous observatories that operate year-round, or collect on our regular ship-based expeditions. Our expeditions mainly take us to three focus regions: Fram Strait between Greenland and Svalbard, the Eurasian sector of the Arctic Ocean, and the Weddell Sea in the Atlantic sector of the Southern Ocean.