Climate change not responsible for world’s largest iceberg, says British Antarctic Survey
The world’s largest iceberg has calved from the western side of the Ronne Ice Shelf in Antartica - but it is considered a natural event, not attributed to global warming.
British Antarctic Survey researchers spotted the ‘megaberg’, now named A-76, in recent images captured by the Copernicus Sentinel-1 mission on the Polar View portal.
Slightly larger than Majorca, or the county of Somerset, it measures about 170km in length and is 25km wide and is floating in the Weddell Sea.
Its 4,320 square kilometre area means it takes over from A-23a iceberg, currently 3,880 sq km and also floating in the Weddell Sea, as the world’s largest.
Dr Kaitlin Naughten, an ocean modeller at British Antarctic Survey, said: “Calving is an essential way for ice shelves to stay in balance. Large calving events only occur occasionally, and they can be very dramatic, but they are not necessarily a sign that the system is changing. There is currently no evidence that the Ronne Ice Shelf is calving more often as a result of climate change.”
Dr Alex Brisbourne, a glaciologist at BAS who has worked on the Ronne Ice Shelf, added: “Iceberg A-76 is huge, about the size of the county of Somerset in the UK. It wouldn’t make the top 10 list of the biggest known icebergs of all time though.
“This calving is part of the natural cycle of the Ronne Ice Shelf. The ice shelf is constantly being fed ice from the Antarctic continent, and eventually chunks break off the ice shelf in this way, forming these big flat icebergs and maintaining a balance. Because they are already floating, as they melt, icebergs do not contribute to sea level rise in a significant way. They have been known to eventually get stuck in places like South Georgia in the South Atlantic, disrupting the feeding of seals and penguins.
“We know that the ocean around Antarctica is warming as a result of global heating but the Weddell Sea, where iceberg A-76 sits, is not currently experiencing this warming. Elsewhere around the Antarctic continent however, the warming ocean is melting other ice shelves and this is allowing the ice to drain more quickly off the continent, increasing the rate of sea level rise. Of course, this sea level rise isn’t restricted to Antarctica, it affects sea level around the world, including here in the UK, increasing the frequency and severity of storm surges and coastal flooding.”
The iceberg was confirmed by the US National Ice Center using Copernicus Sentinel-1 imagery.
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