Ocean forced evolution of the Amundsen Sea catchment, West Antarctica, by 2100

• Main Authors: Alevropoulos-Borrill, Alanna V., Nias, Isabel J., Payne, Antony J., Golledge, Nicholas R., Bingham, Rory J.
• Format: Text
• Language: English
• Published: 2019
• Subjects: West Antarctica; Amundsen Sea; Antarc*; Antarctica; Ice Sheet; Ice Shelf
• Online Access: https://doi.org/10.5194/tc-2019-202; https://www.the-cryosphere-discuss.net/tc-2019-202/

The response of ice streams in the Amundsen Sea Embayment (ASE) to future climate forcing is highly uncertain. Here we present projections of 21 st century response of ASE ice streams to modelled local ocean temperature change using a subset of Coupled Model Intercomparison Project (CMIP5) simulations. We use the BISICLES adaptive mesh refinement (AMR) ice sheet model, with high resolution grounding line resolving capabilities, to explore grounding line migration in response to projected sub-ice shelf basal melting. We find a contribution to sea level rise of between 2.0 cm and 4.5 cm by 2100 under RCP8.5 conditions from the CMIP5 subset, where the mass loss response is linearly related to the mean ocean temperature anomaly. To account for uncertainty associated with model initialisation, we perform three further sets of CMIP5 forced experiments using different parameterisations that explore perturbations to the prescription of initial basal melt, the basal traction coefficient, and the ice stiffening factor. We find that the response of the ASE to ocean temperature forcing is highly dependent on the parameter fields obtained in the initialisation procedure, where the sensitivity of the ASE ice streams to the sub-ice shelf melt forcing is dependent on the choice of parameter set. Accounting for ice sheet model parameter uncertainty results in a projected range in sea level equivalent contribution from the ASE of between −0.02 cm and 12.1 cm by the end of the 21 st century.