We thought we knew what caused this mixing – in summer, we thought it was mainly wind and tides, but it never occurred to us that iceberg calving could cause internal tsunamis that would mix things up so substantially.”Īs opposed to the waves caused by wind and tides, tsunamis are caused by geophysical events where water is suddenly shifted, for example by an earthquake or landslide. Ocean mixing influences where nutrients are in the water and that matters for ecosystems and biodiversity. “This is important for us to understand better. When they break, these internal waves cause the sea to mix and this affects life in the sea, how warm it is at different depths and how much ice it can melt. This can cause big waves at the surface but we know now it also creates waves inside the ocean. Lots of glaciers end in the sea, and their ends regularly split off into icebergs. He says: “This was remarkable to see, and we were lucky to be in the right place at the right time. Lead author of the study Professor Michael Meredith (*), who’s head of the Polar Oceans team at BAS, was there. After the calving, this changed dramatically, with temperature much more even across different depths.
Before it broke away, the water temperature was cooler at around 50-100m in depth and warmer below this. The William Glacier typically has one or two large calving events per year, and the team estimated this one broke off around 78,000 square meters of ice – around the area of 10 football pitches – with the front of the glacier towering 40m above sea level. While some ice melts into the ocean, a lot breaks off into icebergs, which range in size from small chunks up to the size of a country.Ī team on board the British Antarctic Survey (BAS) research ship RRS James Clark Ross were taking ocean measurements close to the William Glacier, situated on the Antarctic Peninsula, as the front of it dramatically disintegrated into thousands of small pieces. Ice in Antarctica flows to the coast along glacier-filled valleys. The observations were made from the BAS research vessel RRS James Clark Ross, which is now owned and operated by the Ukranian Antarctic Programme and called Noosfera
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