Antarctica’s role in sea level rise has been an open question.  This new study published in Nature yesterday offers a sobering answer:  as Antarctic ice sheets melt or collapse in the next few decades, sea levels could rise an additional 20 inches by 2100. This height is almost twice as much as predicted by earlier studies, which relied on a combination of Arctic melting and thermal expansion and a minimal amount from Antarctica. This new estimate of sea level rise would take out major coastal cities, like New York, London, Shanghai, and Sydney. The study’s authors add that “in this case, atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.”