Volcanic greenhouse

Volcanoes, such as Mount Vesuvius, that sit on carbonate sediments could represent a previously underestimated source of atmospheric carbon dioxide and may therefore be a contributor to global warming, according to Italian geoscientists.

Giada Iacono-Marziano of the National Institute of Geophysics and Vulcanology in Palermo, and colleagues Fabrice Gaillard, Bruno Scaillet, and Michel Pichavant of the University of Orleans, France, and Giovanni Chiodini of the Vesuvius Observatory, point out that Mount Vesuvius, one of the most infamous of the world’s volcanoes, has been quiescent since 1944. However, this inactivity is currently associated with an insidious phenomenon, elevated carbon dioxide emissions from the volcano.

Vesuvius

This carbon dioxide, which amounts to about 300 tonnes per day, is the equivalent of yearly anthropogenic carbon dioxide emissions by a region of the world such as Chad, Tonga, or the British Virgin Islands. During the last eruptive period, 1631 to 1944, the carbonate-sourced carbon dioxide comprised 4.7 to 5.3 percentage mass of the vented magma, the team adds.

Unfortunately, the precise origin of this carbon dioxide is a matter of debate. However, Iacano-Marziano and colleagues point out that Mount Vesuvius sits on a carbonate sedimentary sequence several kilometres thick, and to them the source of the carbon dioxide is fairly obvious.

Iacono-Marziano and colleagues have now demonstrated how the red-hot basaltic magma of Mount Vesuvius coming into contact with this carbonate bedrock subsumes it and liberate carbon dioxide gas in so doing. This, the team says, explains the carbon dioxide emissions measured at the surface around the volcano.

The team suggests that this kind of assimilation of carbonate rocks by magma probably contributes, to some degree, to the carbon dioxide degassing of several other volcanic centres that are either dormant or active but located over sedimentary rocks. Magma-carbonate interactions could therefore have a major role in global carbon dioxide emissions from volcanoes, which has been underestimated so far, the team concludes.

Further reading

Suggested searches