LONDON (Reuters) - Greenland's huge ice sheet could melt within the next 1,000 years and swamp low-lying areas around the globe if emissions of carbon dioxide (CO2) and global warming are not reduced, scientists said on Wednesday. A meltdown of the massive ice sheet, which is more than three km (1.8 miles) thick would raise sea levels by an average seven meters (yards), threatening countries such as Bangladesh, island in the Pacific and parts of Florida. "Any area that is less than seven meters above sea level would be flooded," said Jonathan Gregory, a climate scientist at the University of...