A new study by Kreuzer et al. (2026, OCEAN ICE Contribution #32) reveals that a critical non-linear response in the Antarctic climate system, the meltwater–stratification feedback, becomes less effective under strong global warming.
This feedback loop, central to OCEAN ICE’s research, works as follows: meltwater from the Antarctic Ice Sheet freshens the surface ocean, increasing stratification and reducing vertical mixing. This traps heat below the surface, warming the ocean near ice shelves' grounding lines and accelerating basal melting, a self-reinforcing cycle amplifying ice loss. However, the study finds that feedback strength depends on the climate state.
Under pre-industrial conditions, additional meltwater substantially reduces vertical mixing, amplifying sub-surface warming. In contrast, under strong global warming, the feedback effect diminishes. This is due to climate-change-induced suppression of Southern Ocean overturning, which already induces strong sub-surface warming. Consequently, additional ice-sheet mass flux has a reduced impact when overturning is already weak. The study identifies a saturation effect in sub-surface warming due to meltwater flux increase under climate warming.
For OCEAN ICE, this underscores the importance of multi-century, coupled simulations that capture dynamic ice-ocean interactions and non-linear tipping behaviors. Understanding these feedbacks is essential for improving sea-level rise projections and informing climate resilience strategies across Europe and beyond.
👉 Read the full study: [Kreuzer et al., 2026, Geophysical Research Letters](https://doi.org/10.1029/2025GL118643)
The author of the article - Torsten Albrecht (PIK)