| 14 Aug 2026
Antarctic meltwater induces competing climate feedbacks in an Earth system model coupled to an Antarctic ice melt emulator
Abstract. Antarctic ice-sheet mass loss is expected to accelerate under future warming, yet its climatic impacts remain poorly represented in Earth system models. Here, we present simulations with the EC-Earth3 Earth system model that incorporate the Antarctic Ice Melt Emulator (AIME), interactively coupled to the ocean component. AIME simulates regionally and temporally varying freshwater fluxes driven by subsurface ocean temperatures over the Antarctic continental shelf, accounts for the delayed dynamic response of the ice sheet, and enables two-way interactions between the climate system and Antarctic ice loss.
Under an abrupt quadrupling of atmospheric CO2, the interactive freshwater forcing gives rise to two distinct feedback regimes. During the transient adjustment phase, enhanced freshwater input strengthens Southern Ocean stratification, suppresses vertical mixing, and modifies continental shelf circulation, leading to enhanced subsurface warming near the base of Antarctic ice shelves. During the subsequent quasi-equilibrium phase, the dominant climatic response shifts: reduced surface warming, increased sea-ice persistence, and decreased global ocean heat uptake weaken the atmospheric warming, ultimately reducing subsurface warming over the Antarctic continental shelf despite continued freshwater input.
Compared with a simulation without interactive Antarctic freshwater forcing, the coupled simulation exhibits lower equilibrium climate sensitivity and reduced global ocean heat storage under identical greenhouse-gas forcing. These results demonstrate that Antarctic freshwater feedbacks evolve over time, with an initial ocean-driven amplification followed by a longer-term atmosphere-mediated damping response. Our findings highlight the importance of representing interactive Antarctic freshwater fluxes in Earth system models to capture coupled ice-sheet-ocean-atmosphere feedbacks and improve projections of future climate change.
General Comments
van der Linden et al. present a very interesting manuscript about the temporal evolution of the climatic feedbacks due to Antarctic meltwater input. The work is very well in the scope of ESD as the investigated processes relate to ice-sheet mass loss, ocean and atmosphere domains as well as local, regional and global spatial scales.
The authors use Linear Response Functions to emulate the Antarctic Ice Sheet freshwater input into the Southern Ocean by interactively evolving ocean forcing. This is a new concept in the context of Earth System Modeling and a valuable step towards fully coupled climate--ice-sheet model setups.
The paper is well structured and written and provides clear reasoning of the presented conclusion.
I recommend the publication of the manuscript based on minor revisions, which are listed in the specific comments below.
Specific Comments
Section 2.2.1:
The Section includes all relevant information. However, I needed to re-read it several times to fully understand the methodology. I suggest to add a small schematic figure that illustrates the concept visually and especially helps readers that are not very familiar with ice-sheet basal melt parameterisations (quadratic, LADDIE, ...) and Linear Response Functions to understand the processing chain.
Fig 5
Fig 12: I think NO-AIME dOHC/dt should be displayed in blue dashed for consistency
l 472: leading to cooler subsurface shelf waters: The overall ocean anomaly is still net positive in AIME experiment. Revise phrasing: cooling is only relative to NO-AIME experiment
l 521-531: add iceberg melt distribution at surface as further simplification/limitation
l 553: again, cooling is only relative compared to non-interactive freshwater input.
Technical Comments
l 347: remove one from