One is a little less than 6 minutes, the other is about 40 minutes; both are about Greenland and the melting of the ice sheet there.
They show literal rivers of melt taking place and running across the surface of the ice sheet.
Some of those streams of rapidly flowing water abruptly disappear when they empty into a giant sink hole in the ice sheet, sinck holes called "moulins."
The strange thing is that it is not perfectly certain what happens to the water when it enters those moulins, other than the water disappears deep down into the ice sheet.
There is speculation that a large lake or lakes is the final destination, rather than the ocean.
More study is being done.
The destination determines sea level rise (SLR), because if the water stays in a sub-glacial lake, there will be no SLR at that time.
There will be no SLR until that lake flows into the sea.
One fear is that such a flow could take place at once en masse, which could cause not only SLR, but also serious damage to the ice sheet itself.
All that could lead to an acceleration in SLR that would at first be slower than expected, but later it could suddenly exceed normal melting and flowing into the sea:
Many scientists have studied how the glaciers and big chunks of ice breaking off the edges of the Greenland ice sheet are contributing to sea level rise. Yet a new research study led by geographers at UCLA is the first to comprehensively examine how the rivers on top of the ice sheet drain meltwater and contribute to sea level rise. Importantly, the researchers found that current climate models, which do not account for subglacial processes, could be overestimating sea level rise because they do not consider the fact that a significant portion of meltwater is stored inside and below the glacier. Not all of the meltwater, in other words, immediately flows out to sea.(Cryopolitics, cf. Greenland Melt Underestimated?). Where the water goes may be the same as what has happened in Antarctica.
Both fieldwork and remote sensing were used to develop the models behind their results, which were published in PNAS, a leading science journal, earlier this week. Vena Chu, a PhD student in the UCLA Department of Geography, explained to Cryopolitics, “This is the first big study focusing on the rivers on top of the Greenland ice sheet. It brings attention to how much water is being transferred over the surface down into the ice sheet through moulins – in other words, sinkholes in the ice sheet.”
The emptying of a lake of melt water took place in Antarctica where it was less expected, so it could happen in Greenland too it would seem:
ESA’s CryoSat satellite has found a vast crater in Antarctica’s icy surface. Scientists believe the crater was left behind when a lake lying under about 3 km of ice suddenly drained.(Cryosat - 2). The suddenness of this type of event could be more troublesome in some cases than normal SLR caused by normal melt.
This could explain some strange, and yet for the most part unexplained, surges in SLR (Agnotology: The Surge - 16).
The previous post in this series is here.
Greenland melt zones: