Multi-Model Evaluation of the Global Marine Methane Hydrate Inventory

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Methane is trapped in seafloor sediments of many of the world's continental margins in the form of hydrate - an ice-like solid that efficiently stores methane. Hydrates represent an immense carbon store, estimated to be comparable to conventional oil and gas reserves. As waters near the sea-floor warms, the thermal conditions that permit hydrate to exist may deteriorate. This may lead to the breakup of hydrate within the sediment with the subsequent release of methane. Methane is a powerful greenhouse gas, its release into the atmosphere leads to further warming - this could lead to a positive feedback loop in which further hydrate is disassociated.Hydrate also acts to cement and strengthen sediment. As hydrate breaks-down, the surrounding sediment may weaken. This can lead to a structural failure of the sediment column and potentially causing a submarine landslide. The geological record contains examples where hydrate disassociation has been implicated in causing large-scale sediment failure and submarine landslides. One of these is the Storegga slide off the Norwegian coast, when around 8,000 years ago a submarine landslide occurred, triggerring a tsunami that reached as far as northern England. Many areas around the Arctic and Atlantic regions remain potentially susceptible to slope failure. The hazard associated with associated tsunamis (i.e. catastrophic flooding) motivates a desire to improve our knowledge of the hydrate inventory.The CMIP5 project is designed to compare the worlds leading state-of-the-art climate models in their ability to model the present climate and make predictions of future climate change. CMIP5 therefore provides a unique opportunity to develope our understanding of the current and future conditions at the sea floor. Using this insight, this project aims to create improved reconstructions of the current hydrate inventory and model how this may change under future climate change.