Future Response of Antarctic Continental Shelf Temperatures to Ice Shelf Basal Melting and Calving

Abstract

We investigate feedbacks between subsurface continental shelf ocean temperatures and Antarctic glacial melt using a coupled climate model. The model was forced with SSP5‐8.5 and an uncoupled projection of basal melt and calving fluxes. SSP5‐8.5 forcing with fixed pre‐industrial glacial melt warms all continental shelves, such that historically “cool” and “fresh” shelves transition to “warm.” Additional glacial melt, added at depth, cools the Eastern Ross, Amundsen, and Bellingshausen seas, suggesting a negative feedback on basal melt—a novel result for a coarse resolution coupled model. From the Weddell Sea, along East Antarctica, and into the western Ross Sea—where continental shelves transition to a “warm” state—additional glacial melt increases temperatures at the continental shelf sea floor, suggesting a positive feedback. The sign of the glacial melt–subsurface temperature feedback is critically dependent on continental shelf properties, climate state, and the vertical distribution of glacial melt inputs.

Winds and Meltwater Together Lead to Southern Ocean Surface Cooling and Sea Ice Expansion

“…Prior studies that have applied anomalous meltwater as forcing have obtained differing magnitudes of impact in different models (Table 1 in N. Swart et al., 2023). The response to meltwater may differ depending on the vertical distribution of meltwater input (M. Thomas et al., 2023), climatological stratification and/or model spatial resolution, with higher resolution permitting improved representation of ocean circulation and the Antarctic slope current (Beadling et al., 2022). Given the lack of available products regarding the spatial distribution of anomalous meltwater entering the ocean around Antarctica, we have assumed a uniform spatial distribution (Figure S3 in Supporting Information ).…”

Current reversal leads to regime change in Amery Ice Shelf cavity in the twenty-first century

“…However, Southern Ocean temperatures are projected to increase in a warming climate (Fox-Kemper et al, 2021;Rintoul et al, 2018). The previous studies predict the increased upwelling of mCDW onto the continental shelf of the AmIS sector, resulting in a shift of cavity regime and consequently an increase of basal melting (Naughten et al, 2018;Kusahara et al, 2023;Thomas et al, 2023;Mathiot and Jourdain, 2023). These studies provide insight into the drivers of warming on the continental shelf.…”

“…These studies provide insight into the drivers of warming on the continental shelf. For example, a freshening in PB increases vertical stratification, and induces the warming (Aoki et al, 2022;Thomas et al, 2023;Kusahara et al, 2023). Another mechanism is related to the poleward shift of westerly winds, which enhances the upwelling of mCDW across the shelf break (Spence et al, 2017;Guo et al, 2019;Verfaillie et al, 2022).…”

Ice shelf basal channel shape determines channelized ice-ocean interactions

“…In addition to channelized basal melting, we quantify the magnitude and properties of the channelized outflows that are of particular concern for assessing the influence of ice shelf basal meltwater on near-coastal waters 50 , 51 , the broader Southern Ocean 52 , 53 , and the global climate system 54 – 56 . The discharge-averaged heat of the outflow (see Methods) for all S1 runs exhibits the quasi-steady value, which is dependent on the channel CSS (Fig.…”