User:DrVolatiles/gas sandbox

Copied from the CO2 in the earth's atmosphere article

Drivers of ancient-Earth carbon dioxide concentration
On long timescales, atmospheric concentration is determined by the balance among geochemical processes including organic carbon burial in sediments, silicate rock weathering, and volcanic degassing. The net effect of slight imbalances in the carbon cycle over tens to hundreds of millions of years has been to reduce atmospheric. On a timescale of billions of years, such downward trend appears bound to continue indefinitely as occasional massive historical releases of buried carbon due to volcanism will become less frequent (as earth mantle cooling and progressive exhaustion of  internal radioactive heat proceed further). The rates of these processes are extremely slow; hence they are of no relevance to the atmospheric concentration over the next hundreds or thousands of years.

Copied from volcanic gas article.

Non-explosive volcanic gas release
The gas release can occur by advection through fractures, or via diffuse degassing through large areas of permeable ground as diffuse degassing structures (DDS). At sites of advective gas loss, precipitation of sulfur and rare minerals forms sulfur deposits and small sulfur chimneys, called fumaroles. Very low-temperature (below 100 °C) fumarolic structures are also known as solfataras. Sites of cold degassing of predominantly carbon dioxide are called mofettes. Hot springs on volcanoes often show a measurable amount of magmatic gas in dissolved form.

this is a new section, I am writing:

Current Emissions of Volcanic gases to the atmosphere
Present day global emissions of volcanic gases to the atmosphere can be characterized as emissions during eruptions and emissions during non-eruptive activity. Although all gases discussed above are emitted to the atmosphere, the emissions of sulfur dioxide (SO2) and carbon dioxide (CO2) have received the most study. Sulfur dioxide (SO2) emissions during eruptions were 2.6 tera grams (1012g or Tg) SO2/year and during non-eruptive periods or passive degassing were 23.2 ± 2Tg SO2/year for the period from 2005 - 2015. It has long been recognized that the SO2 emissions during eruptions is much less than during passive degassing. Carbon Dioxide (CO2) emissions from volcanoes during eruptions were 1.8 ± 0.9 Tg CO2/year during the period from 2005 to 2015. CO2 emissions from volcanoes during non-eruptive activity were 51.3 ± 5.7 Tg CO2/year during the period from 2005 - 2015. Therefore CO2 emissions during volcanic eruptions are less than 10% of CO2 emissions released during non-eruptive volcanic activity. The VEI 6 eruption of Pinatubo Volcano in the Philippines on June 15 1991 released a total of 18±4 Tg of SO2. Such large VEI 6 eruptions are are rare and only occur once every 50 - 100 years. The 2010 VEI 4 Eyjaflallajökull eruption in Iceland emitted a total of 5.1 Tg CO2. VEI 4 eruptions occur about once per year. For comparison, the human activity of burning fossil fuels and the production of cement has released 36,300 Tg CO2 into the atmosphere in 2015. Therefore, the amount of CO2 emitted due to human activity is 600 times the amount of CO2 presently released by volcanoes. Some recent volcanic CO2 emission estimates that are higher than the ones listed above of 51.3 ± 5.7 and 1.8 ± 0.9 Tg CO2/year during non-eruptive and eruptive activity, respectively. An estimate of 540 TgCO2/year and an estimate of 220 - 300 TgCO2/year take into account diffuse CO2 emissions from volcanic regions. Still, even considering the highest estimate of volcanic CO2 emissions of 540 Tg CO2/year, current CO2 emissions by human activity of 36,300 Tg CO2/year is 67 times higher.