Scientists reveal the mystery behind the hole that appeared in Antarctica 8 years ago

A mysterious hole in Antarctica twice the size of Wales, UK, has baffled scientists for the past 8 years. Researchers have finally solved it and uncovered the reason behind the opening, also known as a polynya, that occurred in the winters of 2016 and 2017, per Eurek Alert. Polynya was created due to a complex interaction between wind, ocean currents, the geography of the ocean floor and the transportation of salts and heat to the surface, as per the study published in Science Advances. A team of researchers from the University of Southampton, UK, the University of Gothenburg, Sweden and the University of California San Diego, US, conducted this study.

The polynya known as the Maud Rise was composed in the Wedell Sea and named after the mountain structure submerged in the sea it was formed on. It is a rare phenomenon in the Southern Ocean. The occurrence is related to deep convection and has a significant impact on the heat and carbon budgets. The polynya formed was the biggest in 40 years and lasted for several weeks before reappearing the next year. The formations had stopped happening due to global heating, but it could also be the reason behind its return, per IFL Science.

Scientists supposedly strapped the heads of elephant seals with scientific equipment to unveil the reason behind the Maud Rise Polynya. Along with other conditions, they attributed the formation to the circular current, also known as the Wedell Gyre, which was stronger between 2015-2018, which was the reason behind increased heat and salt transferred to the surface. “This upwelling helps to explain how the sea ice might melt. But as sea ice melts, this leads to a freshening of the surface water, which should, in turn, put a stop to the mixing. So, another process must be happening for the polynya to persist. There must be an additional input of salt from somewhere,” Professor Fabien Roquet of the University of Gothenburg explained.

From the evidence gathered with the help of the seals, they discovered that salt rose from the Maud Rise while the current flowed over it. However, the polynya was not formed directly above the peak but above its northern portion. The reason behind this is an occurrence called the Ekman transport. During this, the water runs at a right angle to the direction of the wind instead of running before it as per the outlet. The Ekman transport has been key to solving the mystery. “Ekman transport was the essential missing ingredient that was necessary to increase the balance of salt and sustain the mixing of salt and heat towards the surface water,” per co-author Professor Alberto Naveira Garabato of the University of Southampton.

The study further explained that the polynya might be causing a general reduction of sea ice in the southern ocean. “The imprint of polynyas can remain in the water for multiple years after they’ve formed. They can change how water moves around and how currents carry heat towards the continent. The dense waters that form here can spread across the global ocean,” co-author Professor Sarah Gillie, University of California San Diego, explained. She added, “For the first time since observations began in the 1970s, there’s a negative trend in sea ice in the Southern Ocean, which began around 2016. Before then, it had remained somewhat stable.”