PhD researcher, Robbie Mallett (UCL) attended COP27 in Sharm El Sheikh, Egypt, with the International Cryosphere Climate Initiative. During the conference he gave talks and appeared on panels in the Cryosphere Pavilion. As well as running the pavilion, the ICCI released the 2022 State of The Cryosphere Report, which Robbie helped to launch to the media and COP participants.
Robbie and the ICCI also campaigned for greater recognition of the cryosphere in COP negotiations. This year the cryosphere was specifically mentioned in the conference’s cover declaration for the first time, and the ICCI coordinated a new multinational coalition, named the Ambition on Melting Ice https://iccinet.org/ambition-on-melting-ice/
Congratulations to CPOM associate, Tamsin Edwards (KCL) who in 2023, will be on secondment as a new Parliamentary “Thematic Research Lead”: helping to provide evidence to Parliament on climate & environmental science.
Tamsin will each join new thematic policy hubs which will bring together staff from POST, the House of Commons Library and Select Committee teams, ensuring greater co-ordination and a better flow of research information through Parliament.
CPOM Director, Professor Andy Shepherd (University of Leeds) joined Simonetta Cheli, ESA’s Programmes and Head of ESRIN (ESA establishment in Italy) and co at the IAC2022 to discuss how ESA is preparing to address climate change. You can also watch Andy Shepherd answering how we raise awareness on climate change and what can scientists do?
“We need to tell people good news stories about climate recovery. There’s hope!”
Scientists monitoring the giant A68A Antarctic iceberg from space reveal that a huge amount of fresh water was released as it melted around the sub-Antarctic island of South Georgia.
Satellites revealed that 152 billion tonnes of fresh water entered the seas around the sub-Antarctic island of South Georgia when the megaberg A68A melted over 3 months in 2020/2021, according to a new study.
152 billion tonnes of water is equivalent to 20 times the amount of water in Loch Ness or 61 million Olympic sized swimming pools.
In July 2017, the A68A iceberg snapped off the Larsen-C Ice Shelf on the Antarctic Peninsula and began its 3.5 year, 4000 km journey across the Southern Ocean. At 5719 square kilometres quarter the size of Wales , it was the biggest iceberg on Earth when it formed and the sixth largest on record.
Around Christmas 2020, the berg received widespread attention as it drifted worryingly close to South Georgia, raising concerns it could harm the island’s fragile ecosystem.
Their findings show that the berg had melted enough as it drifted to avoid damaging the sea floor around South Georgia. However, a side effect of the melting was the release of a colossal 152 billion tonnes of fresh water in close proximity to the island a disturbance that could have a profound impact on the island’s marine habitat.
Anne Braakmann-Folgmann, a researcher at CPOM and PhD candidate at the University of Leeds School of Earth and Environment, is lead author of the study. She said: This is a huge amount of melt water, and the next thing we want to learn is whether it had a positive or negative impact on the ecosystem around South Georgia.
Because A68A took a common route across the Drake Passage, we hope to learn more about icebergs taking a similar trajectory, and how they influence the polar oceans.
For the first two years of its life, A68A stayed close to Antarctica in the cold waters of the Weddell Sea and experienced little in the way of melting. However, once it began its northwards journey across Drake Passage it travelled through increasingly warm waters and began to melt.
Altogether, the iceberg thinned by 67 metres from its initial 235 m thickness, with the rate of melting rising sharply as the berg drifted in the Scotia Sea around South Georgia.
Laura Gerrish, GIS and mapping specialist at BAS and co-author of the study said A68 was an absolutely fascinating iceberg to track all the way from its creation to its end. Frequent measurements allowed us to follow every move and break-up of the berg as it moved slowly northwards through iceberg alley and into the Scotia Sea where it then gained speed and approached the island of South Georgia very closely.
If an iceberg’s keel is too deep it can get stuck on the sea floor. This can be disruptive in several different ways; the scour marks can destroy fauna, and the berg itself can block ocean currents and predator foraging routes. However, this new study reveals that A68A collided only briefly with the sea floor and broke apart shortly afterwards, making it less of a risk in terms of blockage.
By the time it reached the shallow waters around South Georgia, the iceberg’s keel had reduced to 141 metres below the ocean surface, shallow enough to avoid the seabed which is around 150 metres deep.
Nevertheless, the ecosystem and wildlife around South Georgia will certainly have felt the impact of the colossal iceberg’s visit. When icebergs detach from ice shelves, they drift with the ocean currents and wind while releasing cold fresh meltwater and nutrients as they melt.
This process influences the local ocean circulation and fosters biological production around the iceberg. At its peak, the iceberg was melting at a rate of seven metres per month, and in total it released a staggering 152 billion tonnes of fresh water and nutrients.
The journey of A68A has been charted using observations from five different satellites. The iceberg’s area change was recorded using a combination of Sentinel-1, Sentinel-3, and MODIS imagery. Meanwhile, the iceberg’s thickness change was measured using CryoSat-2 and ICESat-2 altimetry. By combining these measurements, the iceberg’s area, thickness, and volume change were determined.
Tommaso Parrinello, CryoSat Mission Manager at the European Space Agency, said: Our ability to study every move of the iceberg in such detail is thanks to advances in satellite techniques and the use of a variety of measurements. Imaging satellites record the location and shape of the iceberg and data from altimetry missions add a third dimension as they measure the height of surfaces underneath the satellites and can therefore observe how an iceberg melts.
Further information:
Image credit: A68A iceberg approaching the island of South Georgia (14 December 2020). The left hand part of the image are clouds. Credit: MODIS image from NASA Worldview Snapshots.
Observing the Disintegration of the A68A Iceberg from Space is published in Remote Sensing of Environment. The article can be found at https://doi.org/10.1016/j.rse.2021.112855.
For additional information contact University of Leeds press officer Anna Harrison a.harrison@leeds.ac.uk
