Questão 25 - FUVEST (USP) Conhecimento Gerais 2026

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    Ice flows across Antarctica and continues to do so as it reaches the edge of the land mass and extends over the ocean. The huge floating tongues of ice often remain attached to the continent. Anything that remains grounded on the land is part of the Antarctic ice sheet; the floating part is an ice shelf. Floating ice shelves surround three-quarters of Antarctica’s coast and make up about 11% of its total area. One of the largest, the Ross Ice Shelf, is roughly the size of France. The George VI Ice Shelf is shown in the image, taken by NASA’s Landsat 8 in January 2020.

    It may seem intuitive that all the ice added to the ocean from melting ice shelves would raise global sea level, but that’s not the case. By Archimedes’s principle, ice shelves floating on the water have already displaced their own weight, so their disintegration or melting won’t change the water level. Ice shelves do, however, regulate the speed of glaciers on Antarctica’s land. Ice shelves act to hold glaciers back. Take¬¬ the shelf away, and the glaciers are free to speed up and flow into the ocean. Any ice and liquid water that the glaciers take with them will raise sea level. Of Earth’s fresh water, 70% is stored in Antarctica’s ice; that is the equivalent of about 58 meters of sea-level rise if all of it were to melt.

Buzzard, S. “The surface hydrology of Antarctica’s floating ice”. Physics Today 75, 28-33 (2022). Adaptado.

 

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