EigoPro 2級 読解 — Rivers of Ice

Rivers of Ice High in the world's mountain ranges, and across the polar regions, lie enormous bodies of slowly moving ice called glaciers. Although they may look completely still, glaciers actually flow downhill like extremely slow rivers, carving valleys and shaping the land over thousands of years. Many of the world's most dramatic landscapes — deep valleys, sharp mountain peaks, and chains of lakes — were created by the patient work of ancient ice. A glacier forms in places where more snow falls in winter than melts in summer. Year after year, new layers of snow press down on the old ones, squeezing them into dense ice. When the ice becomes thick and heavy enough, it begins to move under its own weight. Some glaciers travel only a few centimetres a day, while others, under the right conditions, can move several metres. Glaciers are far more than spectacular scenery. In many parts of the world, they act as natural water towers. Snow that falls in the cold season is stored as ice and then released gradually as meltwater during warmer months, feeding rivers exactly when farms and cities need water most. Hundreds of millions of people in Asia and South America depend on rivers that begin in glaciers, often without ever seeing the ice itself. This is why scientists watch glaciers so closely today. Rising global temperatures are causing glaciers to shrink at a worrying speed; many have already lost a large part of their ice, and some have disappeared entirely. When a glacier vanishes, the river it once fed becomes smaller and less reliable. Researchers say glaciers are one of the clearest signals of a changing climate — a slow-moving warning, written in ice, that the planet is getting warmer.

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