Page 71 - Demo

A melting ice cap creates a waterfall in Svalbard, Norway.THE BIGThe Chacaltaya ski area sits upon a small mountain glacier THAWin Bolivia. Although the area is less than a kilometer long, it oncehosted international ski competitions. In the past ten years, however, the snow has melted very quickly. As the Chacaltaya glacier melts, dark rocks are uncovered. These rocksabsorb more heat, causing temperatures to increase, so the remaining snow melts faster. The cycle seemsunstoppable. Today, the snow is almost gone, and so are Chacaltaya%u2019s days as a popular ski resort.A Global ProblemIn recent years, scientists all around the world have come to a terrifying conclusion. Global warming is a real problem, and one largely caused by human activity. But as experts debate how to solve the problem, ice near the North and South Poles is melting even faster than environmentalists once feared. Ten years ago, scientists warned that the Arctic Ocean could lose all its ice in about a hundred years. Now, they think it could happen much sooner. As climate scientist Mark Serreze says, %u201cReality isexceeding expectations.%u201dGlacier RunThe ice sheet of Greenland is also melting more quickly than scientists predicted. One of its largest glaciers,Jakobshavn Isbr%u00e6, is moving toward the sea faster than expected. In fact, the glacier is moving twice as fast as it was in 1995. Rising air and sea temperatures are two well-known causes. Researchers have also discovered otherunexpectedprocesses that cause glaciers to melt faster. For instance, water from melting ice runs downcracksin the surface and gets between the ice and rock below. This makes it easier for the glacier toslide into the warmer sea water.Some researchers believe that the melting of Greenland%u2019s ice, if it continues, could add at least a meter to global sea levels by 2100. If the ice sheet of Antarctica continues to melt at its current rate, the next few centuries could see at least a two-meter rise in sea levels, forcing tens of millions of people out of their homes.ABCDUnit 10A