"We are witnessing a true reversal of ocean circulation in the Southern Hemisphere—something we’ve never seen before,” explains Antonio Turiel, ICM-CSIC researcher and co-author of the study. “While the world is debating the potential collapse of the AMOC in the North Atlantic, we’re seeing that the SMOC is not just weakening, but has reversed. This could have unprecedented global climate impacts.”
If the crystalline structure of water did not expand from it’s liquid phase (thus lowering it’s density) when it freezes, then ice would not float. Ice would sink trapping everything below it. It’s theorized that this little fact means life likely couldn’t exist if ice didn’t behave this way.