HISEAS
Collaborative Research:
How much and why did Ice Sheets melt during the Last Interglacial (HISEAS)?
The Last Interglacial (LIG, approx. 130 - 115 ka) is the most recent time in Earth’s history when the Greenland and Antarctic ice sheets melted significantly beyond their current present state. This time period therefore provides information on the processes that drive ice sheet melt in a past and future warmer world. HISEAS aims to constrain when, how much, and why LIG ice sheets melted through investigating the role that external drivers (e.g. ocean and air temperatures), boundary conditions (e.g. bedrock elevation), and internal ice sheet processes played in ice sheet collapse. This knowledge is key to refining future projections of ice sheet change.
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We will use the Earth system model CLIMBER-X coupled to the ice sheet model PISM and sea level model VILMA to simulate global ice sheet and sea-level evolution from the penultimate glacial maximum to the end of the LIG (140 – 115 ka). We will calibrate this model with a range of paleoclimatological data. We will compile a comprehensive database of such data including terrestrial and sea-surface temperature, iceberg discharge, sea-ice extent, deep ocean circulation, and vegetation classification and use this to produce time-slice maps for data-model comparison. We will produce new records relevant to understanding climate-ice-sheet interactions (e.g., sea surface temperature, iceberg discharge, and sea- ice extent) using existing deep-sea sediment cores as well as fossil corals. For model calibration we will also use a suite of sea-level observations. We will leverage an existing database and establish new sea-
level records from four locations, including two sites that we already surveyed and sampled and two sites that will be targets for new field campaigns. A sea-level fingerprint analysis will complement the Earth system modeling to provide a parallel estimate of melt contributions during the LIG. Using our data calibrated models we will test the relative roles of external drivers (e.g. temperatures), boundary conditions (e.g. bedrock elevation), and internal ice sheet processes in the evolution of LIG ice sheets.