Independent: Sea levels are predicted to rise twice as fast as was forecast by the United Nations only two years ago, threatening hundreds of millions of people with catastrophe, scientists said yesterday in a dramatic new warning about climate change. Rapidly melting ice sheets in Greenland and Antarctica are likely to push up sea levels by a metre or more by 2100, swamping coastal cities and obliterating the living space of 600 million people who live in deltas, low-lying areas and small island …