A Marginal marine particulate organic carbon flux and δ13C responds to global warming at the Paleocene-Eocene boundary B Our work focuses on elucidating how burial of organic carbon buried on the continental shelves modulates global climate change. We use the Paleocene-Eocene thermal maximum (PETM) as an analogue for ongoing greenhouse-gas induced climate change. A) Organic carbon particles of diverse origin were buried in the Arctic Ocean during the PETM (background image). B) Carbon stabilized as particles (POC) and by association with mineral surfaces (MAC) responded differently among sites. POC burial was particularly dynamic at high sedimentation-rate locations. Total carbon in coastal sediments increased by >1.5 x, providing a strong feedback on atmospheric CO2. C) Carbon isotope ratios of POC buried off the US East Coast track changes in the d13C value of the atmosphere with high fidelity, indicating that this was ‘young’ carbon that would have rapidly sequestered CO2. In contrast, MAC d13C values are lagged, suggesting slower sequestration of C in this fraction. C