Subglacial discharge accelerates future retreat of Denman and Scott Glaciers, East Antarctica

Ice shelf basal melting is the primary mechanism driving mass loss from the Antarctic Ice Sheet, yet it is unknown how the localized melt enhancement from subglacial discharge will impact future Antarctic glacial retreat. Here, we develop a parameterization of ice shelf basal melt that accounts for both ocean and subglacial discharge forcing and apply it in future projections of Denman and Scott Glaciers, East Antarctica, through 2300. In forward simulations, subglacial discharge accelerates retreat of these systems into the deepest continental trench on Earth by 25 years. During this retreat, Denman Glacier alone contributes 0.33 mm/yr to global sea level rise, comparable to half of the contemporary sea level contribution of the entire Antarctic Ice Sheet. Our results stress the importance of resolving complex interactions between the ice, ocean, and subglacial environments in future Antarctic Ice Sheet projections. 

In this data publication, we present the model output and results associated with the following manuscript submitted to Science Advances: “Subglacial discharge will accelerate retreat of Denman and Scott Glaciers, East Antarctica”. We include yearly ice sheet model output between 2017-2300 for models that do and do not resolve subgalcial discharge in the melt calculation. We also include the ice sheet model's initial state. In addition, we include all ocean forcing time-series (temperature and salinity for the control, low emission, and high emission climate forcing scenarios) and the present-day chanellized subglacial discharge flux field over the Denman and Scott Glacier model domain, which are used as input into the melt parameterization. Lastly, we include a MATLAB script that contains the code used for ice shelf melt rate computation as well as a "README" file with further information on all data in this publication. 

Methods
Ice sheet model results: Direct results taken from the Ice-sheet and Sea-level System Model (ISSM, Larour et al. 2012) with no processing applied, provided yearly as *.mat files.

Ice sheet model initial state: Initial state (ice geometry, mesh information, inversion results, etc.) of the ice sheet model containing Denman and Scott Galciers with no processing applied, provided as a *.mat file. The contents of the *.mat file is a MATLAB variable of class "model", which is compatible with ISSM.

Melt parameterization script: Documented MATLAB script ready to run with the provided data sets.

Ocean temperature and salinity timeseries: Bottom ocean temperature (°C) and salinity (PSU) timeseries  (January 1st, 2017 through December 31, 2299) extracted from an East Antarctic configuration of the ocean component of the MITgcm (Pelle et al., 2021). Temperature and salinity were averaged bi-weekly along the ice fronts of Denman and Scott Glaciers (see white dashed contour in figure 1a of the main manuscript text) along the sea floor. Data are provided as *.mat files. Note that the ocean model in Pelle et al. (2021) was run through 2100. In the control and low emission scenarios, we repreat the last 20-years of simulated ocean (2079-2099) conditions through 2300. In the high emission scenario, where a clear warming trend was evident in the ocean temperature after 2050, we extrapolate this warming trend with a square-root function and add this onto the retreated 2079-2099 repearted forcing.

Channelized discharge flux data: Present-day output from the Glacier Drainage Systems (GlaDS) model in units of m3/s over grounded elements of the domain. Data is provided in a *.xyz file (see README.txt for instructions on how to load the data and interpolate onto model mesh using MATLAB). No processing has been applied other than subglacial flux values less than 0.001 m3/s have been removed from the dataset.