Here's why:
* Solubility: CO2 is much more soluble in water than other gases like oxygen or nitrogen. This means that the ocean can absorb and hold significantly more CO2 than the atmosphere.
* Ocean-Atmosphere Exchange: The ocean constantly exchanges gases with the atmosphere. However, due to its high solubility, the ocean acts as a sink for atmospheric CO2, absorbing more than it releases.
* Biological Processes: Marine organisms, like phytoplankton, use CO2 for photosynthesis. This process removes CO2 from the ocean, but it's constantly replenished by the absorption of atmospheric CO2.
While the atmosphere is about 0.04% CO2, the ocean holds about 50 times more CO2 than the atmosphere. This significant difference is a major factor in the global carbon cycle.
