National Public Radio: Scientists have been worried about the West Antarctic Ice Sheet for decades. A new study finds that if it were to collapse, global sea level would rise drastically, though not as much as predicted 30 years ago. Much of the West Antarctic Ice Sheet is vulnerable because it rests on ground below sea level. If warm ocean water gets under it, the ice could start flowing off the continent and into the sea. That ice, and ultimately water, would increase sea levels by a substantial amount. A …