Award: OPP-1941327

ARTEMIS was a collaborative NSF/NERC research project entitled: Accelerating Thwaites Ecosystem Impacts on the Southern Ocean. In the field, ARTEMIS also collaborated with the International Thwaites Glacier Collaboration (ITGC), a joint US/UK initiative investigating the physics of the Thwaites Glacier system within the context of the Amundsen Sea Embayment (ASE) and the coupled ocean-glacier processes driving thinning, melting, and calving (Figure 1). During a joint ITGC/ARTEMIS oceanographic 2022 field campaign, ARTEMIS provided value-added oceanographic and biogeochemical measurements (e.g., trace metals, freshwater tracers, carbonate system, nutrients, organic matter, microorganisms), acquired via shipboard and from autonomous vehicles. The project outcomes presented here relate to the sea-ice/climate component of ARTEMIS (co-I Stammerjohn, CU-Boulder). This component was focused on 2 overarching questions: (1) how do atmosphere-ocean-ice interactions and ice-climate interactions affect polynya dynamics directly (Figure 1; Pickup et al 2025; Zheng et al 2025); and (2) how is variability in the marine icescape (sea ice, fast ice, and icebergs) affecting water mass modification, ocean stratification, and ocean circulation (and hence iron delivery and availability to the euphotic zone) (Stammerjohn et al 2024/SCAR; St-Laurent et al 2024) and how will these interactions change in the future (St-Laurent et al AGU/2025). These 2 questions motivated our analyses of field data and numerical modeling experiments.

A top-down view of the ASE (Figure 1, upper left) highlights the main pathways of two key water masses: (1) warm salty Circumpolar Deep Water (CDW) flowing at depth onto the continental shelf south towards the ice shelf cavities (yellow arrows), and (2) the buoyant meltwater-laden CDW exiting the ice shelf cavities to flow westward with the coastal current or offshore along the deep bathymetric troughs. A significant portion of ARTEMIS sampling was focused along the Dotson Ice Shelf (DIS, Figures 1 and 2), especially at the main inflow and outflow locations, where vertical profiles of ocean currents (Figures 2C, 3A, 3F) and water samples were acquired for freshwater tracers (Figure 3B, 3G) and trace metals (Figure 3C, 3H) (Chinni et al, in review; Chinni et al 2025/AGU), along with other biogeochemical measurements (Schine et al AGU2025; Vassy et al, AGU2025; Yager et al in prep). At the inflow location, southward velocities of warm salty CDW are strongest at depth (Figures 2C and 3A). As CDW circulates within the ice shelf cavity, meltwater is generated, cooling and freshening the now meltwater-laden CDW. Upon exiting at the outflow, the melt-laden CDW dominants the upper ~400m (Figures 2C, 3F), containing elevated amounts of glacial meltwater and dissolved iron (Figure 3G-H).

The ARTEMIS 2022 field observations, together with high resolution (1.5km) 3D coupled ice/ocean/ice shelf/biogeochemical modeling, provided critical observations of the meltwater impacts on ocean-ecosystem interactions and carbon uptake. For the ice-climate (CU-Boulder) component, modeling experiments investigated how changes in the marine icescape (Figure 4) impact ocean-ice shelf interactions, focusing especially on changes to the Thwaites Glacier Tongue (TGT), which in 2011 was at a maximum extent and included a large tabular iceberg B22. But by 2022, the TGT had completely disintegrated, breaking up into countless small individual icebergs. Also notable in 2022 was the vast fast‐ice cover that formed between Thwaites Ice Shelf (TIS) and Pine Island Ice Shelf (PIS).

Based on these 2011/2022 observed changes, different semi-idealized modeling experiments were designed. One of these experiments (Figure 5) quantified changes to both the ocean heat influxes into TIS and PIS cavities and the basal melt rates with/without TGT, iceberg B22, and fast ice cover between TIS and PIS. In response to the changed marine icescape, the influx of ocean heat to both TIS and PIS cavities was increased, with the influx to the western TIS becoming twice as strong in 2022. Results from all modeled experiments indicate ice shelves in the ASE have multiple pathways for ocean heat supply, and that major disruptions in the marine icescape (e.g., 2011 versus 2022) are simply countered with a re-distribution of the heat flux across those pathways, such that high melting rates are maintained (if not enhanced).

These are just a few highlights from the ARTEMIS project. To date, ARTEMIS has resulted in 4 peer-reviewed publications, and over a dozen international conference proceedings, the results of which are currently being expanded into several more peer-reviewed submissions. ARTEMIS also supported 7 early career researchers (ECRs; inclusive of graduate students, postdocs, and new research associates), and each ECR has at least one peer-reviewed publication resulting from ARTEMIS. Members of the ARTEMIS team were also interviewed by CNN meteorologist Allison Chinchar, who published the news article Antarctica's majestic underwater world is trying to adapt to a warmer planet (May 7, 2022). The article addresses key societal topics addressed by the ARTEMIS/ITGC collaboration: melting ice sheets and their effect on global sea level rise and on a highly productive Antarctic marine ecosystem.

Last Modified: 12/13/2025
Modified by: Sharon E Stammerjohn