Methane can come from all kinds of places. But now a team of researchers has discovered over 500 bubbling methane vents just off the east coast of the US that are releasing the gas too.
The team of scientists has been studying the continental margin — part of the ocean floor that divides the coast and the deep ocean. They have discovered a series of at least 570 methane seeps on the Atlantic floor, in an area between North Carolina and Massachusetts.
Sitting at varying depths, between 50m and 1700m, the seeps are a result of methane escaping from methane hydrate — a form of ice with natural gas locked inside it. The researchers reckon that our gradually warming oceans are now reaching a temperature where the methane escapes from the ice, rising as bubbles through the ocean.
The team reckons that there could be as many as 300,000 of these leaks dotted around the globe. Fortunately, the bubbles they release haven't been observed reaching the surface: instead, the methane seems to dissolve and become oxidised as CO2. There's also no suggestion that the CO2 is entering the atmosphere either. The work is published in Nature Geoscience.
The finding does, however, underscore just how much methane lurks within and below our oceans and suggests our current estimates of greenhouse gas sources could be inaccurate. While those stores are currently not a threat to in terms of global warming, this new finding will likely act a stimulus for research to work out if they could one day be. [Nature Geoscience via BBC]