I occasionally hear someone say that volcanoes emit more carbon dioxide than any manmade source. The blog at NOAA’s Climate.gov discusses this “fact” and shows that in fact human activities such as burning fossil fuels, deforestation and cement production put out 60 times as much CO2 as natural sources like volcanic eruptions. Of course, for short periods when a large eruption is underway the carbon dioxide emissions might be higher, but the global annual average is really quite small compared to our manmade production. Volcanoes also put out aerosols which promote global cooling, but that effect only lasts for a few years even for the biggest eruptions. You can read the blog at https://www.climate.gov/news-features/climate-qa/which-emits-more-carbon-dioxide-volcanoes-or-human-activities.
