A glacier in the north of Greenland is melting faster and in a different way than scientists previously thought, and this has troubling implications for the future speed of global sea-level rise. The new discovery was published in the Proceedings of the National Academy of Sciences Monday. The scientists found that warming ocean water had melted a cavity in the bottom of Petermann Glacier taller than the Washington Monument, as The Associated Press reported. If other glaciers in Greenland and Antarctica behave the same way, it could double predictions for how quickly the burning of fossil fuels will melt ice...