June 24, 2021: Online Ocean Circulation and Climate Dynamics Colloquium

When?     Thursday, 24 June 2021 at 3pm
Where?    ZOOM meeting room: https://geomar-de.zoom.us/j/81358596736?pwd=cjdSdGhndTl1MmZIWHk5bVlVWFMydz09
Meeting-ID: 813 5859 6736
Kenncode: 946227

Abstract:
During the last glacial period there were a series of abrupt climate change events that are recorded in ice core records from Greenland and Antarctica. These records show anti-phase temperature changes in the Northern and Southern Hemispheres and these changes are associated with changes in North Atlantic Deep Water formation and atmospheric CO2. This relationship between the north and south is known as the bipolar seesaw. Recently, high-resolution ice core records from the north and south have been precisely methane-synchronized and reveal a 200-year lag in the Antarctic response to a change in Greenland temperature. We explore the mechanisms driving abrupt climate change during the last glacial first using a new time-dependent dynamical box model, which incorporates key dynamical aspects of ocean circulation, including Residual Mean theory in the Southern Ocean. We use this model to develop a new dynamical mechanism, which explains the north-south timing of the bipolar seesaw. Then we look in detail at the deglaciation and reconstruct circulation in the North Atlantic and Southern Ocean using radiocarbon and clumped-isotope temperature measurements on deep-sea corals from intermediate water depths. By measuring multiple tracers on each coral, we are able to make radiocarbon-temperature cross-plots and visualize the different endmember water masses that influence our sites during different time periods across the deglaciation. We find further evidence for salinity-stratification during the glacial and considerable variability in reconstructed radiocarbon and temperature time series, indicating that much of the deglaciation is far from steady state.

List of all OCCD Presentations in 2021