Methane hydrate dissociation across the Oligocene - Miocene boundary

Methane hydrate dissociation has long been considered as a mechanism for global carbon cycle perturbations, climate change and even mass extinctions in Earth's history. However, direct evidence of hydrate destabilization and methane release that coincides with such events is scarce. Here we report the presence of diagnostic lipid biomarkers with depleted carbon isotopes from Southern Ocean sediments, directly pointing to methane release and subsequent oxidation across the Oligocene - Miocene Boundary (OMB, 23 million years ago). The biomarker evidence indicates that the hydrate destabilization was initiated during the peak of the OMB glaciation and sea-level low stand, and persisted over the deglaciation phase. This methane release responded to climate change but also acted as a negative feedback that perhaps facilitated the rapid and mysterious termination of the glaciation in the early Miocene.