Diagram of the carbon cycling in Subglacial Lake Mercer.
Conceptual model of the carbon cycling in Subglacial Lake Mercer, with colors indicating the radiocarbon content of the major measured carbon reservoirs indicating the ‘youngest’ carbon is in the sedimentary organic carbon, a mix of radiocarbon-free and younger material. Purple colored arrows show how that younger carbon (50,000 years old). Credit: Venturelli et al. [2023], Figure 4
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: AGU Advances

The sensitivity of large ice sheet extent to climate over millennial timescales is important for predicting sea level change, but still poorly quantified. Venturelli et al. [2023] use a clever chain of reasoning to put limits on Holocene movement of the grounding line – the location of transition from grounded ice sheet to floating ice shelf in the southern Ross Sea. Their evidence comes from water and sediment samples obtained by drilling through ~1 kilometer of ice to sample a pristine subglacial lake 150 kilometers inland of the current grounding line. The presence of radiocarbon in the lake sediments provides evidence for a mid-Holocene connection to the ocean – the only source of more ‘recent’ (radiocarbon-containing) carbon. By building a model of lake carbon cycling and estimating subglacial hydrology, they further infer that during deglaciation, the grounding line must have been over 250 kilometers inland of its current position.

Citation: Venturelli, R. A., Boehman, B., Davis, C., Hawkings, J. R., Johnston, S. E., Gustafson, C. D., et al. (2023). Constraints on the timing and extent of deglacial grounding line retreat in West Antarctica. AGU Advances, 4, e2022AV000846. https://doi.org/10.1029/2022AV000846

—Susan Trumbore, Editor, AGU Advances

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