CO2 (carbon dioxide) are widely publicised but CH4 (methane) emissions are less known. These more potent methane emissions in the atmosphere are also caused by either natural or anthropogenic sources. When oxidised, CH4 leads to the formation of CO2 emissions in atmospheric ozone. Studies of land and water sources of emissions are more widely known. Kutcherov, Kudryatsev and Serovaiskii wanted to research the role of emissions from gas hydrates on the Arctic seabed.
They examined existing research from Arctic gas hydrates, permafrost areas, East Siberian shelf and the Chukchi, Kara, Laptev, Barents and Beaufort seas. They compared emissions and sinks. They calculated emissions from the multiple data sources and found 3255 Gt (gigatonnes) of CO2 and 5.4 Gt of CH4. Tropospheric methane sinks are mostly from oxidation by a hydroxyl radical (OH with at least one unpaired electron) and methanotropic bacteria in oxic soil (Kutcherov et al., 2023). They noted a continuous increase not just in methane but other light alkanes
The amount of CH4 in the atmosphere annually increases by about 112 Tg (0.112 Gt), and 595 Tg (0.595 Gt) is transformed into CO2…significant concentrations of light alkanes or non-CH4 volatile hydrocarbons (mainly ethane, propane, and butanes) are present in the global troposphere.Kutcherov et al., 2023 Sources of Carbon Dioxide in the Atmosphere
They believe there could be volumes between 500 to 10,000 Gt of gas hydrates on the Arctic shelf which is a seismically active region, and also increasing in temperature, warming the Arctic seas and ocean. Depending on the depth of permafrost layers, the hydrates may dissolve in water layers but at shallower depths, they are emitted into the atmosphere. As Arctic ice continues to be smaller, shallower, and appearing for shorter periods of time, the release of hydrates and solutions for controlling and decreasing the emission into the atmosphere needs further investigation.
Kutcherov V, Kudryavtsev D and Serovaiskii A 2023 Sources of Carbon Dioxide in the Atmosphere: Hydrocarbon Emission from Gas Hydrates in Focus Atmosphere 14 321 Online: http://dx.doi.org/10.3390/atmos14020321