This diagram of the fast carbon cycle shows the movement of carbon between land, atmosphere, soil and oceans in billions of tons of carbon per year. Yellow numbers are natural fluxes, red are human contributions in billions of tons of carbon per year. White numbers indicate stored carbon. The atmospheric net carbon increase is the result of

Responses
A photosynthesis.photosynthesis.
B human emissions.human emissions.
C air-sea gas exchange.air-sea gas exchange.
D respiration and decomposition