Sea Level Rise Seminar, 2025-05-13: Ruth Moorman

Sea Level Rise Seminar Tuesday May 13, 2025 Speaker: Ruth Moorman (Caltech) Title: The Antarctic coastal ocean heat budget is dominated by heat loss to ice shelf melt Abstract: Transport of warm Circumpolar Deep Water (CDW) across the Antarctic continental shelf break is the primary source of heat to Antarctica’s marginal seas and ice shelves. Net heat supplied from the offshore CDW reservoir is ultimately lost to one of two sinks: (i) the atmosphere, either directly or via sea ice, or (ii) the ice sheet, by melting the base of ice shelves and calved icebergs. Ocean models above the regional scale typically neglect the thermodynamics of ice shelf and iceberg melt, and simulations presented here indicate that in doing so they omit the largest ocean heat sink on the Antarctic continental shelf (23 TW, 60% of total heat supply). Suppressing this ocean heat sink in simulations drives enhanced heat loss to the atmosphere through thinned sea ice cover and nonlocal compensatory reductions in heat supply to the continental shelf. These results highlight a source of climate model bias and reframe pathways of ocean heat transport to the vulnerable Antarctic ice sheet.