And now, some researchers have found out that a massive hole, about the size of Lake Superior, has opened up in Antarctica's ice pack but they could not figure out the reason behind this unexpected phenomenon. This isn't the first time it's been spotted, having appeared a year ago for a brief period as well, and long before that it was detected back in the 1970s.
The hole, which is known as a polynya, is about 80,000 square kilometres at its largest, making it the biggest polynya observed in Antarctica's Weddell Sea since the 1970s.
However, the recently discovered polynya is "deep in the ice pack", which is rather unusual, Moore said.
The global warming phenomenon is also in play but scientists aren't sure what this polynya will mean for Antarctica's oceans and climate, and whether climate change effects it at all.
"In the depths of winter, for more than a month, we've had this area of open water", says Kent Moore, professor of physics at the University of Toronto.
The odd ice-free area was first spotted in the 1970s in the midst of the harsh Antarctic winter, despite frigid temperatures - and now, 40 years after it closed, the so-called Weddell Polynya has returned.
"This is hundreds of kilometers from the ice edge". The polynya's occurrence confirms what scientists had previously calculated, and they want to know what made the hole reopen for two years in a row after four decades of not being there. Ocean convection occurs in the polynya by bringing warmer water to the surface, which then melts the sea ice and prevents new ice from forming.
It's larger than The Netherlands, and almost the size of Lake Superior.
One of the biggest reason as to why this polynya remains so mysterious is that it's quite hard to explore such areas. Then it reappeared in 2016, and astonishingly, it again came back this year and its size was even larger than last year. A robotic float, which was sent there for transmitting data from the Weddell Sea surprisingly surfaced inside the polynya last month, stated a news release from the Southern Ocean Carbon and Climate Observations and Modeling project at Princeton.
'The better we understand these natural processes, the better we can identify the anthropogenic impact on the climate system'.
Scientific reference: Mojib Latif et al, Southern Ocean Decadal Variability and Predictability, Current Climate Change Reports (2017).