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Abstract Deep-reaching warming along the boundary of the Antarctic Circumpolar Current and the subtropical gyre is a consistent feature of multidecadal observational estimates and projections of future climate. In the Indian basin, the maximum ocean heat content change is collocated with the powerful Agulhas Return Current (ARC) in the west and Subantarctic Front (SAF) in the east, forming a southeastward band we denote as the ARC–SAF. We find that this jet-confined warming is linked to a poleward shift of these strong currents via the thermal wind relation. Using a suite of idealized ocean-only and partially coupled climate model experiments, we show that strong global buoyancy flux anomalies consistently drive a poleward shift of the ARC–SAF circulation and the associated heat content change maximum. To better understand how buoyancy addition modifies this circulation in the absence of wind stress change, we next apply buoyancy perturbations only to certain regions. Buoyancy addition across the Indian and Pacific Oceans (including the ARC–SAF) gives rise to a strong baroclinic circulation response and modest poleward shift. In contrast, buoyancy addition in the North Atlantic drives a vertically coherent poleward shift of the ARC–SAF, which we suggest is associated with an ocean heat content perturbation communicated to the Southern Ocean via planetary waves and advected eastward along the ARC–SAF. Whereas poleward-shifting circulation and banded warming under climate change have been previously attributed to poleward-shifting winds in the Southern Ocean, we show that buoyancy addition can drive this circulation change in the Indian sector independent of changing wind stress. Significance StatementThis research aims to identify which changes at the atmosphere–ocean interface cause ocean warming localized within strong Southern Ocean currents under climate change. Whereas previous regional studies have emphasized the role of changes in Southern Hemisphere winds, we show that these currents are also sensitive to additional heat and freshwater input into the ocean—even in the faraway North Atlantic. Adding heat and freshwater shifts the currents southward, which is dynamically tied to the “band” of ocean warming seen in both long-term observations and climate change projections. We demonstrate that the warming climate will modify ocean circulation in unexpected ways; the consequences for the ocean’s ability to continue removing anthropogenic heat and carbon from the atmosphere remain poorly understood. 

Abstract The Weddell Gyre mediates carbon exchange between the abyssal ocean and atmosphere, which is critical to global climate. This region also features large and highly variable freshwater fluxes due to seasonal sea ice, net precipitation, and glacial melt; however, the impact of these freshwater fluxes on the regional carbon cycle has not been fully appreciated. Using a novel budget analysis of dissolved inorganic carbon (DIC) mass in the Biogeochemical Southern Ocean State Estimate, we highlight two freshwater‐driven transports. Where freshwater with minimal DIC enters the ocean, it displaces DIC‐rich seawater outwards, driving a lateral transport of 75 ± 5 Tg DIC/year. Additionally, sea ice export requires a compensating import of seawater, which carries 48 ± 11 Tg DIC/year into the gyre. Though often overlooked, these freshwater displacement effects are of leading order in the Weddell Gyre carbon budget in the state estimate and in regrouped box‐inversion estimates, with implications for evaluating basin‐scale carbon transport. 

Utilizing the foundational principals of improvisation, we developed a practicum that gives early career researchers an opportunity to practice the skills necessary to successfully communicate their work orally to both public and professional audiences. Course evaluation data indicate that students find the practicum to be an effective route to increase both confidence and self-efficacy in their communication skills. Due to the instructor’s emphasis on creating a supportive learning community, the practicum can only accommodate a small number of students each semester. To address this challenge, we developed a training institute for instructors to learn how to teach the practicum or incorporate a subset of the content into their existing courses and workshops. Similar to the practicum, we found a 2.5-day Training Institute to be an effective way to train faculty developers how to innovate and incorporate improv-based principles into their local programming.