A coat of floating ice that takes form over Antarctica’s Weddell Sea each and every winter is a puzzling enigma. Once in a while, a huge crater will appear, unveiling the dark, icy waters underneath. Questions such as why do these holes do not show up regularly, or why do they appear at all have never been answered to, but now, a mix of floating robots, satellite imagery, and seals outfitted with ‘little hats’ are helping scientists solve the mystery.
A short history of the mysterious craters in Antarctica
These craters are named ‘polynyas,’ and they’re quite renown and usual. Polynyas are, in fact, useful for Antarctic animals, for instance, seals, whales, and penguins, which swim all over the sea ice and have to resurface to breathe and take a break. However, the Weddell Sea polynya is strange. It was first detected in a satellite image in 1974 close to an underwater mountain known as Maud Rise, and it was massive, approximately the size of New Zealand.
The crater then surfaced again in 1975 and 1976, although air temperatures in that part of the world were below freezing. After the year 1976, though, it appeared to disappear forever. The polynya reappeared in 2016, a bit smaller, about the size of Maine, but noticeable. The next year it appeared again, and a study published earlier this year connected the 2017 polynya to cyclone activity. Even so, as with many worldwide phenomena, it may not have just one cause.
Oceanographer Stephen Riser of the University of Washington said that the research proved that the polynya is, in fact, originated by several factors that have to align for it to appear. In any other year, there could be numerous of these factors occurring, but if they aren’t all happening, there is no polynya.
Current technology is considerably better than it was in the 1970s, and Antarctica has been a focal point for many studies, because of the impacts the climate breakdown will have on the area, and how it might affect the whole world. What this means is that the team has several data streams accessible, including satellite imagining dating decades ago.
Here’s what causes the mysterious craters that appear in Antarctica
Also, data from the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM), a system of floating tools that float in the Southern ocean monitoring temperature, salinity, and current to a depth of 2,000 meters was available. All this started back in 2014. For more than ten years now, researchers have gearing Atlantic elephant seals with Argos Systems tools that contain a GPS, and sensors for temperature and also salinity. This was a third data stream available.
All these methods and data enabled the researching team to construct a picture of the origin of the puzzling holes in the Antarctic ocean. Oceanographer Ethan Campbell of the University of Washington said that the most recent polynya occurred because of several factors, one being the peculiar ocean conditions, and the other being a range of extremely intense storms that occurred over the Weddell Sea.
The researchers discovered that, when powerful ocean winds happen closer to the coast of Antarctica, they grow upward combining in the Weddell Sea, close to Maud Rise. Maud Rise itself then drives dense seawater all around it, concluding in a vortex.
When the sea is significantly salty, winter storms can generate a circulation feedback loop, where warmer water from underneath comes to the surface, and gets cooled by the contact with the atmosphere. This changes the water to be denser, so it falls back down to be switched with more warm water, which follows the same pattern. As a result, all this looping prevents the sea ice from creating. This process could have additional climate consequences because there is a tremendous amount of carbon lying in the Antarctic ocean’s depths, the researching team stated.
Bo has over six years experience as a teacher, advocate and speaker. He has a B.S. from Cornell University, and a Ph.D. in Human rights from Harvard University Graduate School.