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Scientists Study 'Sunburn' In Rocks To Discover 45,000-Year-Old Changes In The Greenland Ice Stream

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Researchers found that environmental events during the past 45,000 years caused the Northeast Greenland Ice Stream to be smaller than what it currently is. Climate change is now taking its toll on it.  ( Mario Tama | Getty Images )

Although it is documented that the ice stream in Greenland has been melting for some time, scientists now believe that this has been happening for many years.

What Did Researchers Discover About Greenland?

The Northeast Greenland Ice Stream (NEGIS) is over 300 miles long and it drains nearly 12 percent of the Greenland ice sheet. It is the second largest body of ice in the world. A new study revealed that the NEGIS has been smaller than it currently is today and it's been like that for 45,000 years.

The study was published on May 14 in the journal Nature Communications.

"There are some parts of the ice sheet that [is] relatively stable and others that show evidence of very rapid retreating — a pattern we're seeing today as well as thousands of years ago," said geologist Anders Carlson, a co-author on the study. "Some of it relates to bed topography — when the bed is below sea level, it stabilizes that part of the ice sheet. In low spots, it is unstable." 

Researchers determined that the NEGIS is really sensitive to environmental changes over the past 45,000 years. In recent years, climate change had taken its toll on the ice stream.

About 41,000 to 26,000 years ago, the NEGIS also experienced a loss of ice. The scientists believe that this was likely due to warmer temperatures during the summer months and low snowfall during the winter months. They also said that the Earth's orbit was closer to the sun 9,000 years ago, which also impacted the ice stream.

How Did They Discover This Ice Loss?

To determine these changes, the researchers reconstructed the periods of changing air temperatures. They also studied the rocks in the NEGIS to research the impact of the sun.

While studying the rocks, the scientists were able to decide where the ice sheet margins were by looking for "sunburn" in the rocks. They determined that the rocks were exposed to cosmic rays. This split the elements and created beryllium-10 in the rocks. This exposure resulted in the NEGIS shrinking over time. 

What Does The Future Hold for NEGIS?

The researchers said that the ice sheet won't retreat until the end of the century. However, the vanishing ice in Greenland could have a lasting impact on the rest of the world. With less ice, the land will absorb most of the heat, which will enhance climate change. In addition, melting ice could cause sea levels to rise and there could be more extreme weather around the world.

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