MSO: Coupling an ice sheet model to EC-Earth to investigate future Antarctic contribution to sea level rise

An Ice Sheet Model (ISM) will be coupled to EC-Earth

In this project an Ice Sheet Model (ISM) will be coupled to EC-Earth, the global climate, and Earth System Model (ESM), which is widely used and further developed at KNMI in collaboration with European partners (about 30 institutes in 12 countries). Besides addressing sea level projections, this development potentially also improves the model’s ability for making global climate projections which will ultimately also contribute to improved KNMI scenarios for the future climate in the Netherlands.

In large parts of Antarctica, the bottom of the sea on which the Ice Sheet rests becomes deeper when moving land inwards. When ice retreats the transition point between floating ice and grounded ice (grounding line) moves further land inwards, and the warm Circumpolar Deep Water (CDW) penetrates further, enhancing melt of the ice-sheet, giving rise to the Marine Ice Sheet Instability (MISI; Figure 1). To assess the associated risk of enhanced sea level rise, the ESM has to be able to simulate MISI, and other instability mechanisms.

Figure 1. Schematic illustration of the climate system in the vicinity of an ice sheet like Antarctica.

We aim for a coupling design in which simultaneously the Greenland and Antarctic Ice Sheets can be online coupled including a two-way interaction with the ocean, i.e. the ocean model provides basal melt rates and the Ice Sheet Model (ISM) provides the freshwater flux to the ocean while the coupled model has to allow grounding line migration and calculates the surface mass balance. To this end we have decided to use the BISICLES ISM, developed in the UK, and hired a postdoc who graduated on work with BISICLES (Claire Donnelly) to do the coupling with help from the group of Tony Payne at Bristol University. 

The coupling method and forcing/interaction from/with EC-Earth will be similar to the protocol followed in the Dutch Knowledge Program on Sea-level rise in which we implement linear response functions to emulate the ISM response in EC-Earth, and the protocol for prescribing interactive freshwater forcing from melting icecaps in EC-Earth within a project funded by the Dutch Polar Program, making the coupling within this MSO project a collaborative team effort of the Sea-level group at KNMI.