'Polynya effect': Scientists discover Switzerland-sized hole in the middle of Antarctica

Apr 25, 2025, 11:30 IST
Subhadra Srivastava

Unusual open water in Antarctica

A large ice-free area appeared above Maud Rise in Antarctica and remained open for several weeks. Known as a polynya, this gap in the sea ice has drawn global scientific attention due to its size, location, and persistence during winter.

What is a Polynya?

A polynya is an area of open water surrounded by sea ice. Though not uncommon in polar regions, the scale and longevity of this particular polynya make it significant for oceanographers and climate researchers.

Role of Ekman transport

Wind-driven ocean currents known as Ekman transport moved saltier, denser water to the region. This process led to increased melting from below the ice, helping maintain the polynya over an extended period.

Maud rise Seamount’s impact

Maud Rise, an underwater mountain beneath the Weddell Sea, influences ocean currents. The area was first noted for similar events in the 1970s. The seamount helps trap warmer water near the surface, which contributes to the melting of overlying sea ice.

Impact of extratropical storms

Extratropical storms and atmospheric rivers added surface heat and helped disperse ice. These weather patterns, which may become more frequent due to global warming, provided energy that sustained the open water

Strengthened ocean currents

In 2017, the Weddell Gyre strengthened, bringing warmer, deeper water upward. This upwelling weakened sea ice from below, contributing to the formation and maintenance of the polynya during the Antarctic winter.

Global implications

The polynya may affect global ocean circulation and climate. It influences the movement of heat and carbon dioxide between ocean and atmosphere, potentially accelerating climate change. It also contributes to deep-water formation, which is key to the global thermohaline circulation.

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