Figure 5.

Scatter plot exploring the relationship between the SO₂ flux (2005–2015 mean; data from ref.³³) and the volcanic gas CO₂/S_T ratio for the population of “measured” volcanoes in Table 1. For Turrialba + Poas (T), we plot the best-guess estimate for the magmatic gas CO₂/S_T ratio for Turrialba volcano (data from 28 top-ranking volcanic point sources of SO₂ (left) and CO₂ (right) during 2005–2015. Data are from Table 1. SO₂ fluxes are 2005–2015 means from ref.³⁰. The CO₂ fluxes are calculated from SO₂ using measured or predicted CO₂/SO₂ ratios (see Table 1). Different volcano groups are identified by different colours. The global CO₂ budget is dominated by CO₂-rich Group 2–3 arc volcanoes. Two rift volcanoes (Nyiragongo and Nyamuragira) and one within-plate (WP) volcano (Kilauea) appears in the top-10 list of CO₂ emitting volcanoes.