Biomarker data from marine sediments samples retrieved from the following sites: (i) Tanzania (TDP Site 14), (ii) New Jersey Margin (Site 174AX), (iii) Denmark (Fur) (iv) Tasman Sea (ODP Site 1172) and (v) the High Arctic (IODP Site 302). Sediments are ~56 million years old and span the Paleocene-Eocene Thermal Maximum. Biomarker data was compiled from previous publications (see ref. 1-5 below) or extracted and analysed via gas chromatography-mass spectrometry (GC-MS). Biomarker data was then apportioned into plant, soil, and algal organic carbon using a three-end member mixing model (https://github.com/FluvialSeds/petm_mixing_model). The dataset also includes climate variables from ocean-atmosphere climate model simulations. This was generated previously (see ref. 6) or obtained using the Hadley Centre model. The analysis was supported by Royal Society Dorothy Hodgkin Fellowship DHF/R1/191178 and NERC Pushing the Frontiers Grant UKRI1272. In total, 14 individual datasets are included: Sheet 1: Lipid biomarker data and OC burial fluxes from Tasman Sea (Source data; Fig. 1) Sheet 2: Lipid biomarker data and OC burial fluxes from New Jersey Margin (source data: Fig.1) Sheet 3: Lipid biomarker data and OC burial fluxes from the High Arctic (source data: Fig.1) Sheet 4: Lipid biomarker data and OC burial fluxes from Denmark (source data: Fig.1) Sheet 5: Lipid biomarker data and OC burial fluxes from Tanzania (source data: Fig.1) Sheet 6: Average mass accumulation rate (MAR) data for High Arctic, New Jersey Margin, Denmark, and Tasman Sea between the latest Paleocene and PETM (source data: Fig. 2a) Sheet 7: Average mass accumulation rate (MAR) data for High Arctic and New Jersey Margin during the pre-PETM, PETM body and PETM recovery (source data: Fig. 2b, 2c) Sheet 8: DeepMIP model ensemble-derived estimates of mean annual precipitation under different CO2 scenarios (source data; Figure 3) Sheet 9: HadCM3L-derived estimates of plant and soil OC stocks under different CO2 scenarios (Source data: fig.4) Sheet 10: Total organic carbon burial flux (in MtC/yr-1) in marine sediments during the PETM assuming 270kyr duration Sheet 11: MOSES2.1 soil parameters used within the HadCM3B palaeoclimate model. Sheet 12: Lipid biomarker data from Mississippi (Yedema et al., 2022) and proportion of plant, soil, and marine OC Sheet 13: #ringstetra data for Denmark Sheet 14: #ringstetra data for New Jersey Margin References: (1) Stokke, E.W., et al., (2020) Earth and Planetary Science Letters, 544 (2) Sluijs, A., et al., (2020) Climate of the Past, 16(6) (3) Sluijs, A., et al., (2011) Climate of the Past. 7(1) (4) Carmichael, M.J., et al., (2017) Global and Planetary Change. 157 (5) Elling, F.J., et al., (2019) Nature Communications. 10(1) (6) Lunt, D.J., et al., (2021) Climate of the Past. 17(1)