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ENCYCLOPEDIC ENTRY
ENCYCLOPEDIC ENTRY

Deglaciation

Deglaciation

Deglaciation is the melting of glaciers or a decrease in ice sheets. While deglaciation helped mark the end of the last ice age, glacial retreat in the 21st century helps support the scientific theory of global warming.

Grades

5 - 8

Subjects

Climatology, Conservation, Earth Science

Image

Ice Falling from Perito Moreno Glacier

One result of deglaciation is ice loss from glaciers like that seen from the Perito Moreno Glacier in Santa Cruz Province, Argentina.

Photograph by fredtamashiro

Deglaciation refers to the retreat or melting of ice sheets and glaciers. The last period of significant deglaciation marked the end of the most recent ice age, about 8,000 to 17,000 years ago.

Glaciers retreat when ice mass is lost through the melting of ice or through sublimation, the process by which ice evaporates. Several factors impact the rate of deglaciation. A rise in carbon dioxide levels in the atmosphere results in an increase in global temperatures. This warming is considered a primary cause of deglaciation in the 21st century. Such global warming, coupled with diminished yearly snowfall, causes glaciers to retreat faster than they can be replenished. This can result in significant glacial retreat, such as when the Greenland glacier lost more than 10 billion tons of ice in one day in August of 2019.

Deglaciation can have two major effects. First, glaciers shrink in size as the ice mass decreases. Then, much of this meltwater runs off into the ocean, causing a global rise in sea levels.

Glaciers are remnants of the last ice age, which ended, at the latest, 8,000 years ago. They contain clues embedded in ice, like frozen bubbles of ancient air, that provide scientists with evidence of past climate changes. Scientists have used what they have learned from the last period of deglaciation to help predict the future of Earth’s glaciers. They have noticed that in recent decades, rates of glacial retreat have increased, releasing tons of ice in the form of water each year. If these trends continue, scientists believe that glacial melt will result in the loss of major frozen reservoirs of freshwater and a minimum of a 1.1-meter (3.5-foot) rise in sea level by the end of the 21st century.

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Director
Tyson Brown, National Geographic Society
Author
National Geographic Society
Production Managers
Gina Borgia, National Geographic Society
Jeanna Sullivan, National Geographic Society
Program Specialists
Sarah Appleton, National Geographic Society, National Geographic Society
Margot Willis, National Geographic Society
Producer
Clint Parks
other
Last Updated

May 20, 2022

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