The present-day distribution of subsea permafrost beneath high-latitude continental shelves has implications for sea level rise and climate change since the Last Glacial Maximum (~20,000 years ago). Because permafrost can be spatially associated with gas hydrate (which may be thermodynamically stable within the several hundred meters above and below the base of permafrost), the contemporary distribution of subsea permafrost also has implications for the persistence of permafrost-associated gas hydrate ...

Bottom simulating reflections (BSRs) are seismic features that are imaged in marine sediments using high-energy, impulsive seismic sources such as air guns or generator-injector guns. BSRs often cut across sediment stratigraphy and are interpreted as marking the deepest depth at which gas hydrate can exist. Gas hydrate is a naturally occurring and widely distributed frozen form of water and gas (usually methane) stable at low temperatures (up to about 25 degrees Celsius [°C]) and intermediate pressures ...