Sea level rise: New iceberg theory points to areas at risk

"If this starts to happen and we're right, we might be closer to the higher end of sea level rise estimates for the next 100 years," said Jeremy Bassis, assistant professor of atmospheric, oceanic and space sciences at the U-M College of Engineering, and first author of a paper on the new model published in the latest issue of Nature Geoscience.

Iceberg calving, or the formation of icebergs, occurs when ice chunks break off larger shelves or glaciers and float away, eventually melting in warmer waters. Although iceberg calving accounts for roughly half of the mass lost from ice sheets, it isn't reflected in any models of how climate change affects the ice sheets and could lead to additional sea level rise, Bassis said.

"Fifty percent of the total mass loss from the ice sheets, we just don't understand. We essentially haven't been able to predict that, so events such as rapid disintegration aren't included in those estimates," Bassis said. "Our new model helps us understand the different parameters, and that gives us hope that we can better predict how things will change in the future."

The researchers have found the physics at the heart of iceberg calving, and their model is the first that can simulate the different processes that occur on both ends of the Earth. It can show why in northern latitudes - where glaciers rest on solid ground - icebergs tend to form in relatively small, vertical slivers that rotate onto their sides as they dislodge. It can also illustrate why in the southernmost place - where vast ice shelves float in the Antarctic Ocean - icebergs form in larger, more horizontal plank shapes.

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