Main reasons of the increasing carbon dioxide emission in the atmosphere

In the last 100 years, the amount of carbon dioxide (CO2) in the atmosphere kept increasing. Whether the increasing of CO2 in the atmosphere is related to an increasing of volcanism on Earth has become a controversial topic. Some researchers suggested that volcanism caused the increasing of CO2 in the last 100 years, while others thought that the increasing of CO2 is a result of anthropogenic emissions. According to recent data and evidence, the latter is more possible.

Some researches exhibit that volcano can be a major source of CO2 increasing in the atmosphere. A study finished in 1997 showed the composition of volcanic gases from Galeras Volcano in Colombia. Basic solution and an equipment called Japanese box were used to collect and analyze the acidic gases in the air from the volcano, and titration was used to test CO2, and the data of gas composition from 1989-1992 was recorded (Alfaro & Zapata, 1997). According to the result, the amount of CO2 collected from the volcanic gas changed every year, but it always overweighed other gases such as HCl and SO2. The researchers also pointed that Galeras volcano was active and had several times of eruption in last century (Alfaro & Zapata, 1997), which shows that it can release a large amount of CO2 to the atmosphere.

Another research that was done recently studied Katla as a volcano that is an important source of volcanic CO2 emission on the earth and is active recently even if it has not erupted for a century. The concentration of CO2 in different areas around Katla was observed, stimulated and modelled using aircraft, and the emission rate was calculated based on the result of the observation and modelling. According to the calculation, the CO2 emission rate of Katla was about 12–24 kt per day (Ilyinskaya et al., 2018). Researchers also state that Katla is the third major source of volcanic CO2 emission, and the volcano is unrest due to the movement of magma (Ilyinskaya et al., 2018).

On the other hand, there are also evidences demonstrate that CO2 in the atmosphere increases due to the anthropogenic emissions. A research in 1984 calculated CO2 emission rate of fossil fuels combustion from 1950 to 1982. It showed that the emission rate maintains an upward trend, even if it dropped a little bit from 1979 (5, 373×106 t) to 1982 (5, 102×106 t) (Marland & Rotty, 1984). In 2002, the

increasing CO2 in the atmosphere in Phoenix, Arizona of the U.S. was studied, and the result showed that most of CO2 emissions in Phoenix were from fuels combustion of vehicle, which was 67,737,789 mg per year and about 80% of CO2 production in Phoenix (Koerner & Klopatek, 2002). A recent research calculated and analyzed the CO2 emission rate from consumption, production, import and export in each cities of Hebei Province, China in 2012, and it exhibited that the maximum emission rate based on consumption and production in one of these cities was about 550mt, while the largest emission rate from import and export in one of these cities was 320mt approximately (Mi et al., 2018).

Even though there are a number of evidences support both side, it is still more convincible that major reason for the increasing of CO2 is anthropogenic emissions. According to recent studies, the global emission rate of volcanic CO2 was about 637mt per year (Burton et al., 2013), and the global anthropogenic CO2 emission had reached 32,000mt per year approximately (Friedlingstein et al. 2010), which outweigh the global volcanic CO2 rate a lot.