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larsen-bAn international team of scientists has concluded that warmer air temperature caused the collapse of the Larsen-B ice shelf.

The team has published a report of their findings in the journal Science, alleging that they found no evidence of structural damage that would have led to the collapse, nor signs that warmer seawater eroded the shelf from below. Both possibilities were put forth when the massive ice shelf split off from the Antarctic continent in 2002.

The international team, led by Michele Rebesco of the Italian National Institute of Oceanography and Experimental Geophysics, and Eugene Domack of the University of South Florida, debunked the warmer water theory when they found that water had been regularly running beneath the shelf for the last 12,000 years.

In their report, they write that the break was instead caused by a perpetual process of warming and refreezing due to rising surface temperatures. First, warmer air heated the ice at the top of the shelf. This led to pools of water forming on the ice, which in turn heated the ice below. As the ice warmed, water seeped into its cracks. In the winter, the water would freeze and expand, eventually splitting the shelf.

Antarctica contains enough frozen water to raise sea levels 190 feet. A continent-wide melt is unlikely in the near future, but when massive shelves (Larsen-B is bigger than the nation of Luxembourg) slide into the ocean, they do displace enough water to cause sea level rise.

Today, six glaciers in West Antarctica are in a state of “irreversible melt” and both Antarctic and Greenland ice sheets are melting at an “unprecedented rate.” This will have a significant impact on the world’s coasts in the coming century, driving populations inland and inundating cities such as New Orleans, Miami and Venice, Italy.

According to Domack, the northern part of the Larsen-C ice shelf (four times the size of the Larsen-B shelf) is currently showing signs of instability.

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