Newswise: In the mid-1970s, the first available satellite images of Antarctica during the polar winter revealed a huge ice-free region within the ice pack of the Weddell Sea. This ice-free region, or polynya, stayed open for three full winters before it closed. Subsequent research showed that the opening was maintained as relatively warm waters churned upward from kilometres below the oceans surface and released heat from the oceans deepest reaches. But the polynya -- which was the size of New Zealand --...