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Southern Ocean getting warmer and saltier, will 'change the way the planet works'

Iceberg and large fragments of drifting ice floating in front of the Antarctic Peninsula. Photo: AFP / Claudius Thiriet Warmer, saltier water from deep in the Southern Ocean has started rising to the surface, bringing up more carbon dioxide, and causing Antarctic sea ice to melt. Earth Sciences New Zealand, formerly the [National Institute of Water and Atmospheric Research principal scientist of marine physics Dr Craig Stevens told Morning Report that the data - from a satellite, and a robot beneath the surface - had only been released a couple of days ago, and that "lots of the bigger picture stuff" still had to be analysed. If it was confirmed that the warmer, saltier water had made it harder for more sea ice to form, "that's a very big story, and it will sort of confirm the trend that we're seeing around Antarctica with significant reductions in sea ice," he said. It is in contrast with earlier data that showed the Southern Ocean was actually getting progressively less salty since the 1980s. But Stevens said that was before a satellite had been used. "For decades our measurements were just sort of little pinpoints from a particular vessel [that] would go here or there, and we would get a single sample. "So that was showing a freshening through to about a decade ago - near the seabed or the seafloor - and since around 2015 that has reversed. "What this new analyses of satellite data of salinity is confirming that happening at the surface." Stevens added that being able to detect salinity - the salt in the water - from satellite was the most interesting thing about the research. It will mean that we will be able to gather better data on salinity over time, and how that might be impacting sea ice. "Ultimately it is about the conditions that allow that sea ice to form, and if those conditions are changing and making it harder, that will flow through into sort of changed ecosystems. "So it'll change sort of the biology around Antarctica, but it'll also change weather patterns, and it'll change heat content in the ocean, so it'll change the way the planet works." Sign up for Ngā Pitopito Kōrero , a daily newsletter curated by our editors and delivered straight to your inbox every weekday.