Planet
Does the Amazon produce 20% of the world's oxygen?
Phytoplankton: 50–80% of O₂
Does the Amazon produce 20% of the world's oxygen?
This is a persistent myth. The Amazon does produce vast amounts of oxygen through photosynthesis, but it consumes nearly all of it through respiration (decomposition of plant matter). The net oxygen contribution is close to zero. Most atmospheric oxygen is maintained by marine phytoplankton, which produce roughly 50–80% of Earth's oxygen.
Source: Field et al. (1998), Science; NASA Earthdata