If the Greenland ice shield and a portion of the Arctic shield melt away, it would raise the water surface by 40 feet around the globe. If that happens, it would put under water many cities, including London, most of Florida as well as over 250 million people in China. Scientists say at the rate we are going it will happen in about 100 years, possibly within 50 years, considering China is building a new coal plant every week.