Sorry. Dioxide.
Remember this, one volcanic eruption spews more carbon (dioxide) than humans have produced since the start of the Industrial Revolution.
https://www.climate.gov/news-featur...-carbon-dioxide-volcanoes-or-human-activities
"Human activities emit 60 or more times the amount of carbon dioxide released by volcanoes each year. Large, violent eruptions may match the rate of human emissions for the few hours that they last, but they are too rare and fleeting to rival humanity’s annual emissions. In fact, several individual U.S. states emit more carbon dioxide in a year than all the volcanoes on the planet combined do."