Amazonia and oxygen

To understand the difference, separate gross photosynthesis from the net balance. Estimates put the Amazon’s gross contribution to global photosynthetic oxygen production at roughly 6–9%, but the ecosystem consumes nearly as much oxygen through respiration and decomposition. The ocean produces about half of Earth’s gross oxygen, and marine life consumes about as much. So what matters is not only how much oxygen is made, but how much remains in the atmosphere over the long term.