Estimation of Gridded Atmospheric Oxygen Consumption from 1975 to 2018

Atmospheric Oxygen (O₂) is one of the dominating features that allow the earth to be a habitable planet with advanced civilization and diverse biology. However, since the late 1980s, observational data have indicated a steady decline in O₂ content on the scale of parts-per-million level. The current scientific consensus is that the decline is caused by the fossil-fuel combustion; however, few works have been done to quantitatively evaluate the response of O₂ cycle under the anthropogenic impact, at both the global and regional scales. This paper manages to quantify the land O₂ flux and makes the initial step to quantificationally describe the anthropogenic impacts on the global O₂ budget. Our estimation reveals that the global O₂ consumption has experienced an increase from 33.69 ± 1.11 to 47.63 ± 0.80 Gt (gigaton, 10⁹ t) O₂ yr⁻¹ between 2000 and 2018, while the land production of O₂ (totaling 11.34 ± 13.48 Gt O₂ yr⁻¹ averaged over the same period) increased only slightly. In 2018, the combustion of fossil-fuel and industrial activities (38.45 ± 0.61 Gt O₂ yr⁻¹) contributed the most to consumption, followed by wildfires (4.97 ± 0.48 Gt O₂ yr⁻¹) as well as livestock and human respiration processes (2.48 ± 0.16 and 1.73 ± 0.13 Gt O₂ yr⁻¹, respectively). Burning of fossil-fuel that causes large O₂ fluxes occurs in East Asia, India, North America, and Europe, while wildfires that cause large fluxes in comparable magnitude are mainly distributed in central Africa.