A giant hole more massive than the Netherlands has opened up in Antarctica. Scientists are now investigating to know how it was formed.
Polynyas are geographical areas of unfrozen sea within the ice pack. These areas of open water surrounded by sea ice are known to play a crucial role in the formation of new sea ice and deep water. Although polynyas occur regularly in the Arctic and the Antarctic, they rarely occur in the open ocean.
What makes the polynya in Antarctica's Weddell Sea interesting for scientists is that it is deep in the ice pack. Atmospheric physicist Kent Moore, from the University of Toronto, said that it must have formed through other processes that are not well understood.
A polynya in the same area was also observed here in the 1970s but observation tools then were not nearly as good as the ones available today, so the hole was largely unstudied. It went away for four decades until it reopened for a few weeks last year. Now the hole is back again, and scientists are trying to understand what is going on.
"In the depths of winter, for more than a month, we've had this area of open water," Moore said. "It's just remarkable that this polynya went away for 40 years and then came back."
Link To Climate Change
Climate change, which is impacting Antarctica and the rest of the world, is possibly responsible for this mysterious hole, but Moore said that blaming global warming for this phenomenon is premature. Scientists, however, say that the hole will have wider effect on the oceans.
"When sea ice forms in polynyas or elsewhere, salt is expelled into the water, raising the salinity of the near-surface water. The salt increases the density of the surface water, making the surface water heavier than the water below, causing it to sink. In some cases, the high-density surface water mixes with other masses and sinks all the way to the ocean bottom," the National Snow and Ice Data Center (NSIDC) explained.
As Antarctica goes through massive changes right now, scientists hope to understand why a gaping hole suddenly opened up, and this could shed light on larger systems at play. Researchers want to know how a polynya occurs and if climate change indeed influences this process.
"Global warming is not a linear process and happens on top of internal variability inherent to the climate system. The better we understand these natural processes, the better we can identify the anthropogenic impact on the climate system," said Mojib Latif, from the GEOMAR Helmholtz Center for Ocean Research Kiel, who is part of a team that studies the Weddell polynya.