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West Antarctic Ice Shelf Breaking Up from the Inside Out

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The continent of Antarctica is bigger than the United States of America and Mexico combined; it is covered mostly in deep ice that reaches as deep as one-and-a-half kilometer in some places. Most of this ice sits on bedrock, but it slowly flows off the continent’s edges; along the western edge, giant glaciers drag down towards the sea, and when these glaciers meet the ocean, ice shelves are formed.

Recent images of the Pine Island Glacier—part of the ice shelf that bounds the West Antarctic Sheet—have shown that the glacier is undergoing rapid retreat, bringing more ice from the inside of the ice sheet into the ocean, which, on melting, would flood major coastlines around the world. In 2015, roughly 580 square kilometers of iceberg broke off from the glacier; however, a new image processing software being tested by Ohio State researchers has brought to light some changes in images taken before the event.

The images have presented evidence that a rift formed at the base of the ice shelf in 2013. Two years later, the rift was still moving upward, until it broke through the ice surface in August 2015, sending the iceberg a drift over 12 days in late July and early August 2015. Although this was the first time researchers discover that the west Antarctic was melting, they have seen similar rifts in Greenland ice sheet in areas where ocean water has oozed inland along the bedrock and begun to melt the ice underneath.

Rifts usually form at the margins of an ice shelf, where the ice is thin and subject to breakage; shockingly, the rift in the Antarctic ice originated from the center of the ice shelf and propagated out to the margins. This suggests that something weakened the center of the ice shelf; one possible explanation so far is that warm water is circulating beneath the ice shelf. Scientists say that the more the bottom of the ice shelves melt, the more ice is exposed to warm water.

Scientists have discovered a one-and-a-half kilometer deep rift valley hidden beneath the ice in West Antarctica, which is believed to contribute to the ice loss. This rift valley is hard to see and connected to warming ocean, which influences contemporary ice flow and loss by steering coastal changes further inland. This valley could have never been detected if it had not been for the ice-penetrating radar system towed behind a skidoo driven across the flat ice surface over a distance of 2400 kilometers. The discovered valley oddly lies with the flat ice surface over a distance of 2414 kilometers, which is greater than the distance between London and Athens.

The melting process is uncontrollable; the shelves will collapse and Antarctica’s glaciers will flow into the sea. Many of the world’s major cities and shipping ports will be swamped, and will eventually have to be abandoned, leading directly to the displacement of hundreds of millions of people and food insecurity. Since thinning ice counts for 10% of the global sea level rise, it is significant to understand and observe current context of change, which would allow more accurate future predictions for increases in global sea level to be made.

References

sciencedaily.com
abdn.ac.uk
phys.org
phys.org

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