Question: Why does the ocean produce more oxygen than plants?

Dawn Lau answered on 16 Jun 2016:

I’m not an expert, but this is what I think. Tiny organisms called phytoplankton live in the water, and via photosynthesis, produce oxygen that gets released into the atmosphere. There is a lot more ocean than plants on land – approximately 70% of the planet is covered with water. So it would make sense that the oceans produce more oxygen than plants, just because there’s more ocean than oxygen-producing plants on the land.