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Iceberg collides with glacier tongue.
Photo Credit: NASA

Collision course

Massive iceberg spawns second giant berg after banging away at glacier tongue

An iceberg the size of Rhode Island collided with the Mertz Glacier Tongue External U.S. government site last month, spawning a second berg nearly as big. The Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA’s Aqua satellite External U.S. government site captured the event, as pictured above and at below right. The original iceberg, called B9, broke from the Ross Ice Shelf External U.S. government site in 1987. It took the massive iceberg more than two decades to drift slowly out of the Ross Sea and along the coast to the Mertz Glacier in East Antarctica. Along the way, it broke apart, one segment becoming the massive B-09B iceberg that collided with the glacier tongue.

Iceberg dislodges glacier tongue.
Photo Credit: NASA
Iceberg B-09B dislodges part of the Mertz Glacier Tongue in East Antarctica.

The glacier tongue had previously contributed to keeping a section of the ocean free of ice, a condition known as a polynya. With part of the glacier gone, the area could fill with sea ice, which would disrupt the sinking ability of the dense and cold water, according to a story in DiscoveryNews External Non-U.S. government site. This sinking water is what spills into ocean basins and feeds the global ocean currents with oxygen. As there are only a few areas in the world where this occurs, a slowing of the process would mean less oxygen supplied into the deep currents that feed the oceans. Other scientists say this would only be a problem if the situation lasted for years or decades.

For more information about polynyas, see previous Antarctic Sun articles: Pulse on polynyas and Record flight.