A mysterious hole has been spotted in Antarctica's winter sea ice cover, which is as big as the Indian state of West Bengal. A similar hole opened past year too.
At its largest the polynya measured 80,000 kilometres - making it larger than the Netherlands and roughly the same size as the USA state of Maine.
Martin says that the re-appearance of the hole at this time confirms the center's previous calculations; GEOMAR has posited a model that explains the polynya as part of natural climate processes.
A vast hole has re-opened in Antarctica, and it could have something to teach us about climate change.
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.
At its peak, the Weddell Polynya measured a staggering 80,000 square kilometers (roughly 31,000 square miles).
"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.
A polynya typically forms farther offshore, driven by the upwelling of warm water according to NASA.
"This is now the second year in a row it's opened after 40 years of not being there", Moore said. "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", said Prof.
One of the biggest reason as to why this polynya remains so mysterious is that it's quite hard to explore such areas.
Still, it's unclear how often the Weddell Polynya re-emerges, and how long it will linger now that it's opened back up.
Scientific reference: Mojib Latif et al, Southern Ocean Decadal Variability and Predictability, Current Climate Change Reports (2017).
Working with the Princeton-based Southern Ocean Carbon and Climate Observations and Modelling (SOCCOM) group, Moore and his colleagues are using observations from deep-sea robots and satellites to study the phenomenon, which in the 1970s was first detected on the same site. But scientists are denying to conclude that this has happened due to global warming. As that water becomes colder and denser, it sinks and thus allows more warm water to rise above and keep the hole open. "We don't really understand the long-term impacts this polynya will have".