The emissions of CO2 and other volatiles from the world’s subaerial volcanoes
Volcanoes are the main pathway to the surface for volatiles that are stored within the Earth. Carbon dioxide (CO 2 ) is of particular interest because of its potential for climate forcing. Understanding the balance of CO 2 that is transferred from the Earth’s surface to the Earth’s interior, hinges on accurate quantification of the long-term emissions of volcanic CO 2 to the atmosphere. Here we present an updated evaluation of the world’s volcanic CO 2 emissions that takes advantage of recent improvements in satellite-based monitoring of sulfur dioxide, the establishment of ground-based networks for semi-continuous CO 2 -SO 2 gas sensing and a new approach to estimate key volcanic gas parameters based on magma compositions. Our results reveal a global volcanic CO 2 flux of 51.3 ± 5.7 Tg CO 2 /y (11.7 × 10 11 mol CO 2 /y) for non-eruptive degassing and 1.8 ± 0.9 Tg/y for eruptive degassing during the period from 2005 to 2015. While lower than recent estimates, this global volcanic flux implies that a significant proportion of the surface-derived CO 2 subducted into the Earth’s mantle is either stored below the arc crust, is efficiently consumed by microbial activity before entering the deeper parts of the subduction system, or becomes recycled into the deep mantle to potentially form diamonds.