# How do oceans absorb CO2?

Aug 15, 2015

1) Differences in pressure between the air and the ocean cause carbon dioxide to be exchanged and 2) algae and phytoplankton absorb carbon dioxide.

#### Explanation:

The ocean can absorb carbon dioxide (${\text{CO}}_{2}$) in 2 ways: diffusion from the atmosphere and through photosynthesis in plankton and algae.

Carbon dioxide moves between the atmosphere and the ocean by molecular diffusion: a difference between ${\text{CO}}_{2}$ pressure in the atmosphere and ocean causes ${\text{CO}}_{2}$ to be exchanged (source). The ${\text{CO}}_{2}$ moves from the air to the water, when the atmospheric pressure of ${\text{CO}}_{2}$ is higher. The ${\text{CO}}_{2}$ is dissolved in the ocean because it is soluble.

The solubility of carbon dioxide varies based on salinity and temperature of the water and there is a finite amount that the water can absorb. The colder the water, the more ${\text{CO}}_{2}$ can be dissolved.

The solubility of ${\text{CO}}_{2}$ in water is demonstrated in the video below.

Another way in which the ocean absorbs ${\text{CO}}_{2}$ is through some of its lifeforms. Phytoplankton and algae both photosynthesize in the ocean. They both consume ${\text{CO}}_{2}$ using sunlight and release ${\text{O}}_{2}$.