A sudden and puzzling shiftFor decades, the icy waters surrounding Antarctica behaved in a way that puzzled scientists. From the late 20th century through the early 2010s, Antarctic sea ice was actually expanding—despite global warming trends elsewhere. Then, almost abruptly around 2016, that pattern reversed. Sea ice began to shrink dramatically and has remained at unusually low levels ever since.This sudden shift raised a critical question: What changed? Understanding Antarctic sea ice is not just about the polar regions—it plays a crucia...