June 21, 2024
1 Solar System Way, Planet Earth, USA
Discovery

Another giant iceberg from Antarctica breaks free

In May 20, 2024an iceberg measuring 380 square kilometers (~147 mi2) broke off from the Brunt Ice Shelf in Antarctica. This event (A-83) is the third significant calving of icebergs in this region in the last four years. The first arrived in 2021, when A-74 broke away from the ice sheet, while an even larger iceberg called A-81 followed in 2023. The separation of this iceberg was captured by two Earth observation satellites: that of the ESA. Copernicus Sentinel-1 and NASA satellite 8 satellites, which provided radar images and thermal data, respectively.

The iceberg has been officially designated A-83 for him US National Ice Center, which assigns names based on the Antarctic quadrant where the iceberg was first sighted. Since Brunt is located in the eastern Weddell Sea, its icebergs are given an 'A' designation while numbers are assigned sequentially. Routine monitoring of ice shelves using satellites allows scientists to track the effects of climate change in remote regions such as Antarctica. In particular, scientists can monitor how ice shelves retain their structural integrity in response to changes in ice dynamics and rising atmospheric and ocean temperatures.

Brightness temperature data from the US Landsat 8 mission. Credit: ESA/USGS

This calving event (like its predecessors) was caused by the weakening of the ice at McDonald Ice Rumples and the extension of the 'Halloween Crack' onto the ice shelf. The Copernicus Sentinel-1 mission relies on radar images to return images throughout the year, regardless of whether it is day or night. This is especially important during winter, when there is virtually no sunlight for six months (known as the Antarctic Night). Missions like Landsat 8 rely on thermal imaging to help scientists characterize the thickness of the ice sheet.

As the image above shows, thinner ice appears warmer as it has a temperature closer to that of open water, while thicker continental ice appears darker. Temperature differences between the ocean and ice sheets also help scientists identify where the calving line is. Fortunately, the iceberg does not threaten the British Antarctic Survey's research. Halley VI Research Station, an international research platform that observes terrestrial, atmospheric and space climate. While still located on the Brunt Ice Shelf, the station was relocated in 2017 to the Caird coast after the outer ice shelf was deemed unstable.

The current loss of Antarctic ice is one of the clearest signs of rising global temperatures and a grave warning. In addition to contributing to sea level rise, coastal flooding, and extreme weather, the loss of polar ice causes Earth's oceans to absorb additional solar radiation, causing temperatures to rise even further. Monitoring polar ice sheets is vital for adaptation and mitigation strategies, as detailed in the IPCC Sixth Assessment Report (AR6).

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