Assessing the impact of ocean temperature on the contribution of the Greenland ice sheet to future sea-level rise with a heuristic statistical approach

Abstract:

We present large ensembles of simulations of the contribution of the Greenland ice sheet
to sea-level rise under RCP2.6, 4.5 and 8.5 future scenarios over 300 years, including
several extended simulations over millennia. To this end, we utilise the ice sheet model
SICOPOLIS coupled with the regional climate system model of intermediate complexity
REMBO. The loss of ice into fjords via outlet glaciers is resolved in a heuristic statistical
approach. In this framework, we recently included into our model an ocean temperature
parameterization to assess the impact of ice loss of the Greenland ice sheet. This work
precedes our planned more comprehensive approach, which will resolve all important ice
loss processes in a model of intermediate complexity of the Greenland glacial system.

Our large ensembles of simulations under future scenarios serve to estimate the uncertainty
of the impact of future ocean temperatures on the state of the Greenland ice sheet. A suite
of initial configurations of the ice sheet is generated via paleo simulations over two glacial
cycles by introducing present-day and Eemian constraints, such as a range in the mass
balance partition, the shape of the ice sheet, the Eemian ice surface elevation change at
an upstream position of the NEEM and further local constraints. The paleo simulations support
the choice of the range of parameters of our ocean temperature parameterization. The large
ensemble simulations together with the paleo constraints enable us to improve estimates on
the range of the possible impact of future changes in ocean temperature around Greenland
on the ice loss of the Greenland ice sheet.