evidence: The transport of carbon dioxide stored in the Earth's lithospheric mantle beneath the Hyblean Plateau in southern Italy at a depth of approximately 50 to 150 kilometers is responsible for the exceptionally large CO2 emission of Mount Etna. That is the result of research conducted by an international team of geologists, including researchers from the Universities of Florence (Italy) and Cologne (Germany), and from the Istituto di Geologia Ambientale e Geoingegneria of the Italian National Research Council (CNR). To reach this conclusion, the team determined the ratios of a particular set of elements in the magmas emitted by the volcanoes using cutting-edge, high-precision measurement methods. The results have been published in the article "A carbon-rich lithospheric mantle as a source for the large CO2 emissions of Etna volcano (Italy)' in the journal Geology. Over the geological times, variations in atmospheric CO2 depended mainly on volcanic emissions, which are difficult to estimate because they are not directly related to the volume of the magmas erupted. Indeed, some volcanoes show exceptionally large emission of CO2 when compared to the amount that can be dissolved in their magmas. Etna is perhaps the most striking example, contributing to 10 per cent (9000 tons/day) of the present global volcanic CO2 emission. That is three times more CO2 than a volcano like Kilauea (Hawaii) emits, which erupts four times more magma.