In early 2022, surprising data were released about the A68A iceberg, a chunk of almost 14km x 8km that broke off the Larsen C shelf around 2018 or 19. Scientists from the University of Leeds published a study in the journal Remote Sensing of Environment indicating that, since the breakage, the ice mass has dumped 152 billion tons of fresh water into the ocean.
According to experts, the largest melt happened between 2020 and 2021 over a three-month period, after the iceberg detached from the Larsen-C shelf in Antarctica in July 2017. The amount of freshwater from the iceberg now in marine waters corresponds to 61 million Olympic-size swimming pools.
The iceberg, twice the size of Luxembourg, undertook a journey of 4,000 kilometers, over 3 years, across the Southern Ocean. At first, the iceberg stayed close to the Antarctic, leading scientists to believe that it might stay close to the shelf, but as it began its journey towards warmer waters the melting increased considerably.
South Georgia’s islands and the wildlife of the area
During its trajectory, the iceberg generated alarm about possible damage to the South Georgia Islands, located about 1,300 kilometers southeast of the Falklands. According to researchers, the melting prevented the iceberg from grounding on the seabed, avoiding ecosystem damage from this cause. However, there are still concerns about the secondary effect of the tons of freshwater released and its impact on the archipelago’s marine habitat.
There are concerns about the secondary effect of the tons of freshwater released and its impact on the archipelago’s marine habitat.
South Georgia is formed by a group of islands that have an extensive ecological reserve and serve as habitat for Antarctic animals. For this reason, experts feared for the future of the wildlife of this important area for the planet.
For example, South Georgia is the largest refuge for king penguins. Unfortunately, this particular species is already threatened by climate change, since they need to migrate to obtain food and reproduce. The warming of the sea could change the patterns, cause a displacement and provoke the reduction of the population.
The A68A data and the concerns of experts
According to information revealed through satellite monitoring by the Polar Observation and Modeling Center and the British Antarctic Survey, A68A was 235 meters thick and shrank to 67 meters. The iceberg briefly collided with the bottom and subsequently began to break up. This behavior reduced the risks of destroying wildlife and blocking the passage of predators and their feeding route.
The researchers monitored the thickness through CryoSat-2 and ICESat-2 altimetry. Meanwhile, the area was recorded with a combination of MODIS, Sentinel-1 and Sentinel-3. With these measurements they were able to know the thickness, volume change and area of the iceberg, which helps experts to calculate the trajectory of the major loss and impact.
The researchers tracked each movement to determine how the disturbance might impact the habitat. In addition to meltwater, icebergs also release nutrients as they move with the ocean current, which can promote biological production. For this reason, experts want to determine whether this large amount of water had a negative or positive impact on the island’s ecosystem.
After a huge crack caused the iceberg to break off from the Larsen-C ice shelf, the massive iceberg was monitored during its trajectory. Scientists feared that it would break into small pieces, preventing satellite tracking of its path and impact course. However, they were surprised when the iceberg retained 70 percent of its mass after a long time drifting.
The detailed study may also help experts learn about the routes and influence of icebergs taking similar trajectories. Experts explain that shelves usually seek equilibrium, so the detachment is usually part of natural processes.
Climate change or natural process?
Concern about climate change is entirely reasonable, and scientists are conducting research to study the consequences. However, experts point out that the detachment of iceberg A68A is not necessarily related to the consequences of climate change; it may be evidence of the natural cycle of decomposition of these ice shelves.
Using satellite images, experts have discovered other cracks in the Larsen-C shelf that could cause the iceberg to collapse if they continue to grow. These blocks over the ocean could add about 10 centimeters into the sea over the years.
It has been vital for the researchers to monitor the trajectory of this iceberg to its end. The data obtained through the study yields fascinating evidence that will allow experts to form a basis for future trajectories, impacts and behavioral patterns of these ice masses.
Image credit: Henry Páll Wulff
