Freshwater injection into bands across the North Atlantic are a mainstay of climate modelling when investigating topics such as climate change or the role of glacial runoff in the glacial climate system. However, this approach is unrealistic and results in a systematic bias in the climate response to a given flux of freshwater. We evaluate the magnitude of this bias by comparison to two other approaches for introducing freshwater into a coupled climate model setup for glacial conditions.

Freshwater, in the form of glacial runoff, is hypothesized to play a critical role in centennial- to millennial-scale climate variability and climate transitions. We track the routing of glaciologically constrained freshwater volumes in glacial ocean simulations. Our simulations capture important generally not well-represented small-scale features (boundary currents, eddies). We show that the dilution of freshwater as it is transported to key climate regions reduces the freshening to 20 %–60 %.

We present a multi-proxy record of Holocene glacial meltwater input, sediment transport, and sea-ice variability off East Antarctica. Our record shows that a rapid Antarctic sea-ice increase during the mid-Holocene (~ 4.5 ka) occurred against a backdrop of increasing glacial meltwater input and gradual climate warming. We suggest that mid-Holocene ice shelf cavity expansion led to cooling of surface waters and sea-ice growth, which slowed basal ice shelf melting.