Atmosphere Journal Entry
Glaciers in Antarctica Melting Fast (October 1, 2004)
Series of photos shows changes to Hektoria Glacier in Antarctica. The top photo was taken a year after the breakup of the Larsen B ice shelf. The middle one is how it looked just after the breakup, and the top one shows it a year after. NASA and NSIDC.
Antarctica's glaciers are melting at a faster and faster rate. Until two years ago, the glaciers were held back by a huge ice shelf called Larsen B. But early in 2002, the northern part of the ice shelf shattered. When it did, thousands of icebergs tumbled into the Weddell Sea. Since then, the glaciers it held back have speeded up their steady flow to the sea.
Ice shelves are thick sheets of glacier ice that spill out over a coastline and float on the ocean. Researchers say the Larsen shelf broke up because of warming temperatures in Antarctica, where it has warmed about 2.5 degrees Celsius (4.5 degrees Fahrenheit) since the 1940s.
After the ice shelf broke up, researchers studied the effects on nearby glaciers. The photos of one of these, the Hektoria Glacier, tell an alarming story. The ice shelf acted like a brake holding the glacier back and slowing its flow. After its collapse, the glacier flowed up to eight times faster than before.
The melting of glaciers is reshaping Antarctica's coastline along its northern tip just below South America. Over the past thirty years, the ice shelves shrunk by more than 5,000 square miles (13,000 sq. kilometers).
When an ice shelf breaks it doesn't affect sea level, since its ice is already floating in the sea. But glaciers sit on land, so their melting can have a big impact on sea level. If all the glaciers on the massive West Antarctic Ice Sheet melted completely, they could raise global sea level by as much as 16 feet (5 meters). This in turn could trigger huge disasters in low-lying areas along coasts around the world.
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