Gas hydrate dissociation linked to contemporary ocean warming in the southern hemisphere

Abstract

Ocean warming related to climate change has been proposed to cause the dissociation of gas hydrate deposits and methane leakage on the seafloor. This process occurs in places where the edge of the gas hydrate stability zone in sediments meets the overlying warmer oceans in upper slope settings. Here we present new evidence based on the analysis of a large multi-disciplinary and multi-scale dataset from such a location in the western South Atlantic, which records massive gas release to the ocean. The results provide a unique opportunity to examine ocean-hydrate interactions over millennial and decadal scales, and the first evidence from the southern hemisphere for the effects of contemporary ocean warming on gas hydrate stability. Widespread hydrate dissociation results in a highly focused advective methane flux that is not fully accessible to anaerobic oxidation, challenging the assumption that it is mostly consumed by sulfate reduction before reaching the seafloor.

Abstract

Ocean warming could enable the release of methane related to hydrate dissociation from the ocean floor, a process thought to have triggered abrupt climate changes in Earth history. Here the authors detect this process in action, observing a massive release of methane from a site in the South Atlantic Ocean.