A massive, mysterious hole in the Antarctic ice has baffled scientists for decades, who just couldn't figure out what caused it to appear.
In the Antarctic Weddell Sea there's a submerged mountain called Maud Rise, and scientists have observed the enormous hole sporadically open up for brief periods in the sea ice there.
It's like a reappearing window into the torrid freezing cold sea below, but after first being spotted in the 1970s and then observed on and off since, it has been a really confusing phenomenon.
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Now, though, we might finally have an answer, after the hole's reappearances in 2016 and 2017 were extensively studied.
The number of techniques used to check out the hole was super impressive, too, ranging from normal-sounding ideas like satellite imaging and computer models, to more inventive ones like fitting sensors to small helmets that seals wore to test the waters in the area - that's not made up, it really did happen.
This helped researchers to establish that the hole was being formed by a process called 'Ekman transport' - which isn't quite as complicated as it might sound.
Alberto Naveira Garabato of the University of Southampton in the UK, part of the research team, explained: "Ekman transport was the essential missing ingredient that was necessary to increase the balance of salt and sustain the mixing of salt and heat towards the surface water."
Ekman transport basically involves the movement of different layers of water around the ocean, often caused by the wind on the surface interacting with massive bodies of liquid below it.
This sometimes combines with already existing currents to push warmer water up towards the surface in the Maud Rise area, and when the conditions are right it results in that huge hole forming - something that's known as a 'polynya'.
Since these often don't stay around for very long, studying them can be a real challenge, but in 2016 and 2017 the Maud Rise polynya was long-lived enough to let scientists really dig into it, coming up with these interesting results.
So, as is often the case, this mysterious freezing cold climate might hold something that seems to have no explanation, but when you put a dedicated team of scientists on the job, there's a pretty solid chance they'll come up with a persuasive theory to figure it out.
Figuring out how this polynya formed will help up to assess future occurrences elsewhere, and to work out whether they're becoming more common or larger as the climate crisis intensifies.