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SOUTHSPHERE: Past behavior of the Southern Ocean's atmosphere and cryosphere

SOUTHSPHERE: Past behavior of the Southern Ocean's atmosphere and cryosphere

Project leads: Prof. Jostein Bakke and Dr. Willem van der Bilt
Collaborators: Several international collaborators, including Christine Lane

The SOUTHSPHERE project, led by Jostein Bakke at the University of Bergen, will explore the past dynamics of the Southern Hemisphere's westerly winds, to inform our understanding of recent and future changes in this globally significant atmospheric pattern.

The Southern Hemisphere's westerly winds play a vital role in regulating Earth's climate by shielding Antarctic ice from low-latitude heat, driving global ocean circulation and storing vast amounts of CO2. Both strength and position of the westerlies are rapidly shifting in the face of ongoing warming. A string of recent studies links these developments to dramatic changes in temperature, precipitation, sea-ice extent and cryosphere stability unfolding throughout the Southern Ocean region. Critically, a lack of baseline information restricts our ability to understand the causes and patterns of these shifts and represent them in the future projections that underpin climate policies.

SOUTHSPHERE will utilise the sensitivity of glaciers to atmospheric climate change and the potential of glacier-fed lake sediments to record the signal of changing climate through time. The work will seek to integrate emerging sedimentological, geochemical, chronological and glacier-modelling tools in a new methodological framework to reconstruct changes in glacier extent, temperature and precipitation on human-relevant timescales. This cross-disciplinary approach will be applied to Holocene sediments from the poorly investigated Kerguelen Archipelago, well-situated in the core southern westerly wind belt. The SOUTHSPHERE team includes Christine Lane at the Department of Geography, University of Cambridge, who will collaborate with Willem van der Bilt (Bergen) on tephrochronological investigations on the cores retrieved from the Kerguelen Archipelago. These data will reveal the potential of using both local volcanic deposits and far-travelled ashes to help date and correlate these valuable archives.

Once completed, SOUTHSPHERE will I) enhance our understanding of the patterns and drivers of Antarctic atmospheric climate change and its interactions with the cryosphere - key priorities of the international Antarctic science community and II) expand the potential of glacier-fed lake sediments as prime palaeoclimate archives.

Lake sediment cores

Lake sediment cores, like these shown being collected in Greenland, will be studied to reveal the nature and timing of past glacier dynamics. Photo credit: Willem van der Bilt