Shrinking Ice Animals aren’t the only ones who depend on glaciers. People do, too. Glaciers are like giant water towers. T ey store vast amounts of fresh water. During summer, temperatures rise. T e ice begins to melt. T e melting ice flows into rivers. People, plants, and animals need this water to live. Water from glaciers in the Himalaya


mountains, for example, pours into many rivers. More than 1.3 billion people in Asia depend on it. Imagine what might happen if this source of water disappeared. T at’s just the problem. Many glaciers are


shrinking. If glaciers melt too quickly, many problems follow. Lakes overflow and flood. Avalanches destroy towns. Icebergs threaten ships at sea. Water supplies dry up. Koppes knows about this problem firsthand.


T is isn’t the fi rst time she has been to Tyndall Glacier. She made this trip several years ago, too. At that time, she took photographs. She measured the height of the glacier’s surface. She checked the position of its terminus. Today, it seems clear to her that there is less


ice. When she studies her two sets of data, she will have proof. Tyndall Glacier is melting. It’s getting smaller.


Melting Glaciers


In fact, almost every glacier on Earth is shrinking. T is isn’t the first time glaciers have melted. Earth’s climate has warmed and cooled many times over millions of years. Scientists aren’t sure exactly why. Each time it warms up, glaciers melt and shrink.


T is time, though, Earth’s atmosphere is


warming faster than ever in modern history. Scientists say human activity is to blame. Burning large amounts of coal, oil, and


natural gas harms the environment. Over time, these activities release harmful gases into the atmosphere. Some of these gases, like carbon dioxide, trap Earth’s heat. As Earth gets warmer, more glaciers melt. As more glaciers melt and do not return, fresh water supplies are put at risk. Aſt er a full day of climbing, Koppes and her


team reach the top of the glacier. She pauses a moment to take in the view. She can see far. An icy wind blasts her face. Beneath her, she hears the glacier groaning. She knows it is moving and changing. T e team will make camp here for the night.


In the morning, they will make the long trip back down the glacier to study the data. T ey’ll share what they know with other scientists.


A melting ice shelf forms at the foot of this glacier.


22 NATIONAL GEOGRAPHIC EXPLORER


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