The Petermann glacier, the largest glacier in the Arctic, is about to lose a major chunk of ice which measures roughly the same size as Manhattan.

Last summer, scientists noticed that the glacier’s tongue had a large crack across it, a crack which measured around 16km in length. The discovery was so concerning that researchers returned to the glacier’s ice tongue this year and have setup cameras and sensors around the glacier to monitor it’s progress and to get a really accurate picture of the breakup, if and when it happens.

Currently, the researchers believe that the ice tongue will break in the next few weeks. In the past week along, a piece of ice measuring 3 square kilometres in size has already broken away, and there are more than 10 cracks in the ice. If the ice tongue does break off completely, the 100 square kilometre section will turn into a 5 billion tonne mass of floating ice.

Having ice tongues break off is normally not a cause for concern – the end points of glaciers are in water and large pieces of ice will naturally break off each year. The ice that is lost through these breakups is balanced by snow that falls at the top end of the glacier. The Petermann ice tongue is causing concern because the ice piece that is being looked at is around half of the glacier’s average annual flow. The flow of ice has increased over the past few years and currently, researchers are unclear as to why this is happening.

One theory is that warmer ocean currents are warming up the ice from below. Combined with warmer temperatures in the air above the ice, it is melting more quickly and therefore causing an increase in the flow of ice.

The more ice that is lost from the glacier, the less resistance the remaining ice tongue will have. This means that the glacier may well flow more quickly and therefore contribute to a rising sea level.

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