a
Photosynthesis: absorbing CO2
b
Synthesis: turning CO2 from the atmosphere into organic molecules
c
Combustion: releasing CO2
d
Decomposition: CO2 into the soil
e
Respiration: releasing CO2 as a byproduct of cellular respiration in living organisms
f
Ocean absorption: CO2 dissolves in the ocean and becomes part of the carbon cycle
g
Fossil fuel burning: burning of fossil fuels releases CO2 into the atmosphere
h
Volcanic activity: volcanic eruptions release CO2 into the atmosphere
i
Deforestation: cutting down trees reduces the absorption of CO2 through photosynthesis, leading to increased CO2 levels in the atmosphere.