Carbon dioxide emission to earth's surface by deep-sea volcanism

Large amounts of CO₂ are transferred from Earth's interior to the surface by volcanism. On a geological time scale, the rate of CO₂ emission has controlled the evolution of Earth's atmosphere and climate, as well as the dynamic processes that take place in the mantle and core. The total rate of natural CO₂ emission from Earth has been estimated on the basis of CO₂ flux from arc, mid-ocean-ridge, and hotspot volcanism. However, previous estimates have overlooked the CO₂ emitted from a recently discovered type of volcanism-petit-spot volcanism-that occurs on the deep-sea floor. Here, we measure the CO₂ and H₂O contents of glassy basalts produced by petit-spot volcanism and estimate the initial contents to be >5 wt% and 1.0-1.1 wt%, respectively. Based on these values and magma flux of petitspot volcanism, we show that the rate of CO₂ emission from petitspot volcanoes (2.7-5.4 × 10¹¹ g CO₂ yr^-1) is a few percent of the CO₂ emissions from arc and mid-ocean-ridge volcanism, and up to ~14% of that from hotspot volcanism. Thus, the contribution to the carbon cycle on Earth of the large amounts of CO₂ that have been emitted from the deep-sea floor by petit-spot volcanism has not previously been recognized.