Sensitivity of the global submarine hydrate inventory to scenarios of future climate change: Supplementary information

The global submarine inventory of methane hydrate is thought to be considerable. The stability of marine hydrates is sensitive to changes in temperature and pressure and once destabilised, hydrates release methane into sediments and ocean and potentially into the atmosphere, creating a positive feedback with climate change. Here we present results from a multi-model study investigating how the methane hydrate inventory dynamically responds to different scenarios of future climate and sea level change. The results indicate that a warming-induced reduction is dominant even when assuming rather extreme rates of sea level rise. Over the next century modelled hydrate dissociation is focussed in the top 100 m of Arctic and Subarctic sediments beneath <500 m water depth. Modelled dissociation rates are particularly sensitive to the vertical hydrate distribution within sediments. Under the worst case business-as-usual scenario (RCP 8.5), global sea-floor methane fluxes could exceed estimates of natural levels by 2100, although subsequent oxidation in the water column could reduce peak atmospheric release rates to 0.7 to 1.4 Tg CH4 yr 1 .