Arctic carbon awakening: Evaluating the reactivity of organic carbon remobilized by past Arctic ice sheet retreat

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Climate change is primarily driven by atmospheric greenhouse gas levels, making it crucial to identify the Earth system processes that regulate these gases in order to better predict and mitigate climate impacts. While the ocean has long been considered the primary driver of atmospheric CO2 fluctuations, oceanic processes alone cannot fully explain the magnitude of the variations or the observed carbon isotopic signatures. In this context, the vast ancient carbon reservoirs stored beneath Arctic ice sheets, which reconfigured in sync with glacial-interglacial climate cycles, likely represent an additional carbon source released during past ice sheet retreats. The overarching aim of ARCTIVITY is to evaluate the reactivity of organic carbon remobilized by Arctic ice sheet retreat, focusing on its impact on the carbon cycle and paleoclimate change. ARCTIVITY will utilize multiple advanced techniques and methodologies to investigate different aspects of the reactivity of glacially-derived organic carbon, archived in marine sediments. These assessments include: (1) thermal reactivity – assessing carbon reactivity in response to thermal decomposition by applying RPO-14C on Northeast Greenland shelf sediments; (2) bioavailability – determining carbon reactivity through its accrssibility to microbial assimilation by leveraging CSRA of IPLs in Northeast Greenland shelf sediments; (3) weathering intensity – evaluating carbon reactivity in response to environmental exposure using sedimentary δ187Re analysis in Beaufort Sea sediments. These analyses will generate new insights into the linkage between Arctic ice sheet retreat and the global carbon cycle, as well as its potential impact on past climate change.