Two of the world’s largest icebergs, including one the size of Big London and an even larger one, the size of Cornwall, are being monitored by British scientists.
There are fears that the frozen giants are drifting into areas where they could affect shipping, fisheries and wildlife.
The huge A81, the size of the capital of England, lifted off the Brunt Ice Shelf in Antarctica in late January and has just been photographed from the air for most of the time.
Glaciologist Dr Oliver Marsh, who returned from the British Antarctic Survey (BAS) Halley Research Station, said: “We knew it was calving.”
“BAS has been monitoring the Brunt Ice Shelf and its chasms for more than a decade.
Huge: Two of the world’s largest icebergs, including one the size of Greater London (pictured) and an even larger one the size of Cornwall, are being monitored by British scientists.
A separate team also sailed around the A76A, which is part of the A76 iceberg that began life after breaking away from the Filchner-Ronne Ice Shelf in mid-May 2021. En route north, the A76 split into three pieces, the largest of which is called the A76A (pictured)
“Since the widening of Chasm 1 was first observed by glaciologists in 2012, BAS science and operations teams have been eagerly awaiting this event.
WHAT IS A HOTEL?
Glacier breakaway is a natural phenomenon caused by the forward movement of a glacier, making its end unstable.
During calving, part of the end of the glacier falls off, often forming an iceberg.
Glacier breakaways are often accompanied by a loud crack or rumble before blocks of ice up to 60 meters (200 ft) high break off and fall into the water.
The entry of this ice into the water can cause large and dangerous waves.
“High-precision GPS instruments as well as satellite data have been used to monitor the widening of the chasm, and in 2016 BAS took the precaution of moving the Halley Research Station inland to protect it.”
A separate team also sailed around A76A, which is part of the A76 iceberg that began life after calving off the Filchner-Ronne Ice Shelf in mid-May 2021.
On the way north, the A76 broke into three pieces, the largest of which is called the A76A and is shaped like a giant ironing board.
At 83 miles (135 km) long and 15 miles (25 km) wide, it’s the largest floating iceberg on the planet – as big as the English county of Cornwall – and heading for the gap between the British Overseas Territories of the Falklands and South Georgia
There are fears that it could move east towards South Georgia and get stuck in the shallow waters of its continental shelf, or possibly head towards nearby islets known as the Shag Rocks.
In both of these areas, this can cause problems for local wildlife and people.
If an iceberg lands in shallow water in this region, it could destroy fauna on the seafloor and disrupt ocean currents and feeding routes for local wildlife.
In addition to the environmental impact, icebergs in the South Georgia area can pose a great danger to local ships.
At 83 miles (135 km) long and 15 miles (25 km) wide, the A76A (pictured) is the largest floating iceberg on the planet – as big as the English county of Cornwall – and heading for the gap between the British Overseas Territories. of the Falklands and South Georgia
Swimming: In January, a team of BAS scientists aboard the RRS Discovery (pictured) completed the A76A circumnavigation.
If the A76A lands on the shallow waters of the seabed off South Georgia, it could destroy the fauna on the seafloor and disrupt ocean currents and feeding routes for local wildlife.
Huge icebergs like these two can take decades to melt and disappear, so they will remain a potential threat for some time to come.
A81 broke free when a large crack in the ice, dubbed Chasm-1, cut through the entire ice shelf. It is now sailing about 93 miles (150 km) from where it started, after turning around and heading south.
HOW DO SCIENTISTS MONITOR THE BRANT ICE SHELF?
Scientists are using a network of 16 GPS instruments to measure any crack-causing deformation of the Brunt Ice Shelf, which reports updates every hour.
These include the European Space Agency’s Sentinel 2 satellites, NASA’s Worldview satellites, America’s Landsat 8 and TerraSAR-X.
They are also using drone footage in situ, as well as ground penetrating radar to image the subsurface.
This data has provided scientists with several ways to measure any cracks with high accuracy.
They also used computer models and bathymetric maps to predict how close the ice shelf was to calving.
The Brunt Ice Shelf is one of the most carefully observed ice shelves on the planet because it is home to the Halley Research Station.
At present, British scientists say that the research station and its surrounding area were practically not affected by calving.
A81 is the second major iceberg in the region in two years. This it is expected to follow in the footsteps of previous icebergs carried westward by the strong Antarctic coastal current.
In January, a team of BAS scientists aboard the RRS Discovery completed the A76A circumnavigation.
While there, they took water samples around the iceberg to better understand its potential environmental impact.
Professor Geraint Tarling, Head of the BAS Ecosystems Group, was on board the RRS Discovery.
“An iceberg of this size will have a big impact on the ocean ecosystems that support the rich diversity of marine life in this Antarctic region,” he said.
“These impacts can be both positive and negative. On the positive side, as the iceberg melts, many nutrients are released that can help grow microscopic plants like phytoplankton at the base of ocean food webs.”
Professor Tarling added: “The negative side is that this same melting on such a large scale releases a lot of fresh water into the ocean, which reduces salinity and makes the waters unsuitable for many of the phytoplankton and zooplankton that feed on them.
These effects can then spread down the food chain to fish, birds, seals and whales.
“Furthermore, if A76A continues on its trajectory towards the Shag Rocks, the shallow seabed digging identified there could have catastrophic consequences for seabed biodiversity communities, including high-value fish feeding areas.”
There are concerns that the A76A could move east towards South Georgia and become stuck in the shallow waters of its continental shelf, or possibly head towards nearby islets known as the Shag Rocks.
Antarctica’s ice sheets hold 70% of the world’s fresh water, and sea levels would rise 180 feet if it melted.
Antarctica contains a huge amount of water.
The three ice sheets that cover the continent contain about 70 percent of our planet’s fresh water, and all of them are designed to warm the air and oceans.
If all the ice sheets were to melt due to global warming, Antarctica would raise global sea levels by at least 183 feet (56 m).
Given their size, even small losses in ice sheets could have global repercussions.
In addition to rising sea levels, meltwater will slow the circulation of the world’s oceans, and a change in the wind belt could affect the climate in the southern hemisphere.
In February 2018, NASA reported that El Niño events are causing the Antarctic Ice Shelf to melt by ten inches (25 centimeters) every year.
El Niño and La Niña are separate phenomena that change the water temperature in the Pacific Ocean.
The ocean periodically fluctuates between warmer than average during El Niño and cooler than average during La Niña.
Using NASA satellite imagery, researchers have found that oceanic events are causing the melting of Antarctic ice shelves and also increasing snowfall.
In March 2018, it was revealed that more of a giant France-sized glacier in Antarctica was floating in the ocean than previously thought.
This raised concerns that it could melt faster as the climate warms and have a significant impact on sea level rise.