Carbon released as hot magma warms the seafloor sediments in the Gulf of California, reports a study online this week in Nature Geoscience. Regions where the sea floor rifts, such as the area studied, had been suggested as sites of natural carbon burial.

Daniel Lizarralde and colleagues analysed seismic and sonar data as well as photographs of the sea floor. They documented magma flow into the sediments up to 50 km from the rift — ten times farther than observed in ridges without sediment cover. They also detected biological communities at the sea floor that are supported by methane emissions from the overlying sediments. The researchers conclude that a thick sediment layer promotes magma flow into a broad area, with implications for methane release.

David Goldberg writes in an accompanying News and Views that “Lizarralde and colleagues have made a start in assessing the contribution of the seafloor spreading process to the global carbon budget.”