Methane seeps from seafloor deposits near Svalbard release less ‘greenhouse gas’ into the atmosphere than other Arctic sites because ocean currents there form an effective barrier. The Arctic contains large volumes of methane stored in forms that turn into gas if temperatures rise or the pressure they are subject to decreases. These forms include methane trapped in marine sediment beneath permafrost as hydrate– a form of methane ice. If methane gas escapes from these deposits, as well as from seafloor reservoirs, it could add to atmospheric warming, causing a positive climate forcing feedback, say investigators....