How do oceans absorb CO2?

1 Answer

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 (CO2) in 2 ways: diffusion from the atmosphere and through photosynthesis in plankton and algae.

http://www.pmel.noaa.gov/co2/file/Ocean+Carbon+Uptake+Imagehttp://www.pmel.noaa.gov/co2/file/Ocean+Carbon+Uptake+Image

Carbon dioxide moves between the atmosphere and the ocean by molecular diffusion: a difference between CO2 pressure in the atmosphere and ocean causes CO2 to be exchanged (source). The CO2 moves from the air to the water, when the atmospheric pressure of CO2 is higher. The CO2 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 CO2 can be dissolved.

The solubility of CO2 in water is demonstrated in the video below.

Another way in which the ocean absorbs CO2 is through some of its lifeforms. Phytoplankton and algae both photosynthesize in the ocean. They both consume CO2 using sunlight and release O2.

For more information:

  1. The Ocean Carbon Cycle
  2. Carbon Dioxide in the Ocean and Atmosphere
  3. The Marine Carbon Cycle Video