On July 12, 2017, the A-68 iceberg – one of the largest ever – broke away from the Larsen C ice barrier on the Antarctic Peninsula. It has been 3 years that the mastodon has drifted in the waters of the southern hemisphere. How and to what extent has the block of ice changed during this time?
It all started in 2014 with the appearance of an imposing fracture in the ice shelf. Over the months and years that followed, the cavity developed regularly until it reached the edge of Larsen C in 2017. On July 12, the phenomenon resulted in the complete and final division of part of the platform: iceberg A-68 was born. Its initial dimensions were 200 kilometers long and 350 meters high. In other words, a very flat specimen.
The ice block then had an area of 5800 km². To give an idea, it is an area equivalent to twice that of Luxembourg. The loss of such an amount of ice will have weakened and redesigned Larsen C forever. The process of fragmentation reduced the effect of buttressing which plays the barrier of ice – which consists in slowing the glacial flow of the continent towards the ocean. In fact, if the iceberg as such does not play on the sea level, the subsequent modifications to the level of the cap favor its rise.
What has become of A-68 since then? In a recent press release, the European Space Agency (ESA) said the iceberg is now 1050 kilometers from its original position. Specifically, it began to penetrate the waters of the South Atlantic, transiting not far from the South Orkney Islands.
During its journey, the mastodon became lighter. In particular, it lost two blocks of ice. One very soon after his detachment – named A-68B – and the other much later, in April 2020 – named A-68C. As it continues to move to warmer latitudes, melting and fragmentation will accelerate. An inevitable fate for a very large part of the icebergs.
The map above illustrates its drift between July 12, 2017 and July 5, 2020. There is a very slow initial movement linked to the presence of an ice floe playing the role of brake. In addition, the map shows the trajectories of all the icebergs detected between 1978 and 2019. There is a medium pattern with an hourly curvature due to the influence of the dominant ocean circulation in the region – i.e. west from the continent.
Finally, note that this very precise monitoring is made possible thanks to the observations provided by the satellites, which participate in the continuous monitoring of the planetary environment. A valuable source of information when you know the danger that the presence of such an object can pose to maritime navigation.