A huge hole has been detected in the Antarctic sea ice cover. The scientific name for this opening is a polynya, (an open space of water surrounded by ice). It is the largest that has been detected since the 1970s in the Weddell Sea. With about eighty thousand square kilometers, it has the approximate extension of Panama.
But its enormous size is not the strangest thing about this huge hole in the ice. Although it is common for polynyas to occur in coastal ice regions, at the edge of the ice sheets; this in particular has occurred in the heart of it, in an area called ice pack , where the ice sheets extend beyond the continent.
Scientists from the SOCCOM ( Southern Ocean Carbon and Climate Observations and Modeling ) project were surprised to discover that a float in the Weddell Sea had emerged within the polynya.
The ocean measurements are being analyzed as part of a study on the pollinia of the Weddell Sea. With these new observations comes the possibility that the secrets of this mysterious and huge hole may, at last, be revealed.
How are polynyas formed?
In recent studies, SOCCOM-affiliated researchers have used climate models to explore why these polynyas form and how they affect oceanic and atmospheric circulation patterns.
However, the difficulty of mounting Antarctic expeditions in winter means that few measurements have been made of these rare events.
Polynyas are therefore common in the coastal areas of ice sheets, but how is it possible for a frozen continental area to sink to create this huge ‘hole’ in the ice?
The SOCCOM project has a range of robotic profile floats that can collect ocean measurements throughout the year, even under sea ice. Scientists note that the huge polynya was formed by deep waters in the Weddell Sea, warmer and saltier than surface waters; therefore, sea currents of convection would have resulted in the destruction of the ice.
As the ice melts, more and more water from the sea is exposed to the cold atmosphere, where it cools and sinks. In doing so, it gives way to the higher temperature waters, and the process repeats itself. All of this hinders the formation of new ice sheets.
It is still too early to say that climate change is responsible for this phenomenon , however it is necessary to study it in depth given its extraordinary nature.
Image: Sea, ice and clouds cover the Wedell Sea in this satellite image, taken on September 25, 2017./MODIS-Aqua/NASA Worldview
