TOPICAL SCIENCE Supplement July 2017 Special Feature: Birth of an Iceberg On the 12th of July 2017, news agencies around the world reported that a huge iceberg, weighing more than a trillion tons, had broken off from the Larsen ice shelf in Antarctica. With an area of 5,800 square kilometres, it was said to be comparable in size to County Galway, or about a quarter the size of Wales. Labelled A68, it is believed to be among the 10 biggest icebergs ever recorded, though not the biggest. Iceberg B-15, which split off from the Ross ice shelf in the year 2000, was twice as big.
The picture below shows the Larcen C Ice Shelf compared to the map of Wales.
Icebergs and the Hydrological Cycle. This so-called ‘calving’ of icebergs is a natural process and is part of the hydrological cycle, so this event was not unexpected. Scientists had been monitoring the situation for some time. Over the past few years, an enormous rift, or crack, had developed in the Larcen C ice shelf. But the calving reduced the area of the ice shelf by more than 12 percent, which has changed the landscape of the Antarctic peninsula.
The rift, in November 2016 The progress of the rift, and the loss of the iceberg, has been carefully followed by analysis of radar images from the European Space Agency’s Sentinel-1 mission, which provides data from the region every six days. The rift suddenly increased in length by 17 km during the last week in May. Then, towards the end of June, the process accelerated, as the movement of ice reached a rate of more than 10 metres per day, but it was not until the middle of July that the iceberg finally broke away. Journalists asked if this event could be linked to climate change, but scientists say there is no evidence for this, nor is it s sign that the ice shelf is disintegrating, as it is inevitable that ice shelves break up as they extend farther out from the land. Nevertheless, when such a large piece breaks off, it is a dramatic event.