The global carbon cycle moves carbon between four reservoirs — the atmosphere, the ocean, the land biosphere and the geosphere's fossil deposits — through fluxes like photosynthesis, respiration, ocean gas exchange and combustion. This 2D box-and-arrow companion draws each reservoir as a box sized by how much carbon it holds, with animated particles along the arrows showing the direction and relative size of each flux. Drag the fossil-fuel emissions and deforestation sliders to add anthropogenic carbon flows on top of the natural balance, and watch the atmosphere box grow, the CO₂ trend line climb, and the fossil-reserve box shrink over simulated decades.