A、How humans are to cope with global warming. B、How unstable the West Antarctic ice sheet is. C、How vulnerable the coastal citie

Among global warming’s most frightening threats is the prediction that the polar ice-caps will melt, raising sea level so much that coastal cities from New York to Los Angles to Shanghai will be flooded. Scientists agree that the key player in this scenario is the West Antarctic ice sheet, a Brazil-size mass of frozen water that is much as 7000 feet thick. Unlike floating ice shelves which have little impact on sea level when they break up, the ice sheet is anchored to bedrock, will blow the sea surface. Surrounded by open ocean, it is also vulnerable, but Antarctic experts disagree strongly on just how unstable it is. Now, new evidence reveals that all or most of the West Antarctic ice sheet collapsed at least once during the past 1. 3 million years, a period when global temperatures probably were not significantly higher than they are today. And the ice sheet was assumed to have been stable. In geological time, a million years is recent history. The proof, which was published last week in Science, comes from a team of scientists from Uppsala University in Sweden and California Institute of Technology who drilled deep holes near the edge of the ice sheet. Within samples collected from the solid substance lying beneath the ice, they found fossils of microscopic marine plants which suggest that the region was once an open ocean, not solid ice. As Herman Engleheart, a co-author from the California Institute of Technology says , ’’The West Antarctic ice sheet disappeared once and can disappear again. ’’
Questions 9 to 12 are based on the passage you have just heard.
9. What is one of the most frightening threats of global warming according to the passage?
10. What do scientists disagree on?
11. What is the latest information revealed about the West Antarctic ice sheet?
12. What do the scientists’ latest findings suggest?