Beneath the ocean floor, bacteria produce methane gas that is regularly released through the sediment and into the sea water as bubble streams. While these gas flares have been observed on continental margins around the world, until now there has been no systematic study of all available gas flow observation data to estimate the total amount of methane escaping from the seafloor. These data are important for the global inventory of carbon and also for analyzing the uptake of carbon dioxide (ocean acidification), and its impact on climate change.