If it were not for the satellite, we would not have found out that it is there, "said physicist Kent Moore, professor at the University of Toronto". The team is making use of observations from deep sea robots and satellites and feels that the data they have now compared to 40 years ago is "amazing".
"It's hundreds of kilometers from the ice edge". Because there is a 40-year span between the last time this happened, there's no clear pattern for scientists to follow.
The harsh winter in Antarctica makes it hard to find holes like this one, so it can be difficult to study them.
Scientists are now working to understand how often the massive hole appears, and how climate change could affect it. In an otherwise thick layer of sea ice, still frozen from the Antarctic winter, the hole is an aberration.
A mysterious "hole" larger than Maryland has reappeared in the middle of Antarctica after 42 years.
In the year 1970, A polynia was observed in the same location, in Antarctica's Weddell Sea but at that time observation tools weren't almost as good, so that hole remained largely unstudied.
"Two of these events happening two years in a row really isn't a long enough kind of trend for us to say it's the result of global warming", Moore told CBC.
Some scientists speculate that the formation of the Weddell polynya is part of a cyclical process, though the details are unclear. This nearly twice the size of the Netherlands and marginally smaller than Ireland.
Usually, a very cold but fresh layer of water covers a warmer and saltier layer of water, acting as insulation. Instead, the Weddel Polynya can be pinned to water stratification in the Southern Ocean, according to scientists at the GEOMAR Helmholtz Centre for Ocean Research who closely following its development.
"This is like opening a pressure relief valve-the ocean then releases a surplus of heat to the atmosphere for several consecutive winters until the heat reservoir is exhausted", Lati added.
Right now, why the hole opened again is a mystery. Due to higher precipitation levels in the region and melting ice, the surface is expected to decouple from deeper water layers. "The better we understand these natural processes, the better we can identify the anthropogenic impact on the climate system", Latif said.