Weddell Sea ice sheet and climate
Deglaciation and climate of the Weddell Sea ice sheet
In the south of the Weddell Sea lies the Ronne and Filchner Ice Shelves. During the coldest part of the last glacial period about 25,000 years ago, the ice in this region may have been up to 1000 m thicker, and extended 400 km further to the north. This additional ice is likely to have reduced global sea level by around 6 m. We are investigating how the climate of this region changed moving forward from the glacial period through to the present, and how the ice sheet responded during the deglaciation and the current Holocene warm period which began around 11,000 years ago.
As the ice reduced in both volume and extent during the deglaciation, several geographic features known as ‘Ice Rises’ developed in the Ronne-Filchner Ice Shelf. These ice rises are independent ice caps. We believe some such as the Berkner Island (the largest at 350 x 150 km) may have only reached their current configuration in the past 4,000 years. Others such as the Korff may have only formed as independent ice rises in the past 1500 years, demonstrating the time it takes for the Antarctic ice sheet to respond to the warmer post-glacial climate.
To determine the climate and dynamic history of these ice rises, BAS uses a range of techniques such as radar to look at the structure and thickness of the ice, seismics to infer the type of bed beneath the ice, and ice core drilling for evidence of past changes in regional climate.
Understanding how past ice sheets have responded to climate change helps us to predict how ice sheets might respond in a future warming world.
- Measure the climate histories from the ice cores we have already recovered from Berkner Island (948m deep, and more than 150,000 years) and the Fletcher Promontory (654 m deep and more than 100,000 years)
- Deploy and use over-snow radar on traverses across ice rises such as Fletcher, Korff, Henry, Fowler, Skytrain to determine the depth and internal structure of the ice
- Deploy phase sensitive radar at target ice rises to measure the vertical velocity of the ice
- Interpret seismic data from example ice rise to determine the basal material
- Drill a new deep ice core to the base of the Korff Ice Rise (around 600 m deep) to recover the climate history, and determine whether the basal material contains recent marine accretion ice that would be indicative that this ice rise was until recently part of the free-floating ice shelf
- Through ice sheet and climate modelling, incorporating the physical data recovered, understand the past and likely future interaction between the stability of the ice sheet and the regional climate
- Ice core scientists (Mulvaney, Thomas, Capron, Massam)
- Laboratories (Benton, Tuckwell, Ludlow, Northrop)
- Ice sheet dynamics and modelling (Hindmarsh, Martin, Kingslake)
- Climate modelling (Sime, Hastings)
- Seismics (Smith, Brisbourne)
LGGE, Grenoble; LSCE, Paris; University of East Anglia; University of Durham