Abrupt periods of global warming between 57 and 50 million years ago—known as the Early Palaeogene hyperthermal events—were associated with the repeated injection of massive amounts of carbon into the atmosphere1, 2, 3, 4. The release of methane from the sea floor following the dissociation of gas hydrates is often invoked as a source5. However, seafloor temperatures before the events were at least 4–7 °C higher than today1, which would have limited the area of sea floor suitable for hosting gas hydrates6, 7. Palaeogene gas hydrate reservoirs may therefore not have been sufficient to provide a significant fraction of the carbon released. Here we use numerical simulations of gas hydrate accumulation8 at Palaeogene seafloor temperatures to show that near-present-day values of gas hydrates could have been hosted in the Palaeogene. Our simulations show that warmer temperatures during the Palaeogene would have enhanced the amount of organic carbon reaching the sea floor as well as the rate of methanogenesis. We find that under plausible temperature and pressure conditions, the abundance of gas hydrates would be similar or higher in the Palaeogene than at present. We conclude that methane hydrates could have been an important source of carbon during the Palaeogene hyperthermal events.
At a glance
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