How can the ocean’s capacity as a carbon sink be increased?
The oceans make up the world’s largest carbon sink, soaking up a third of manmade CO2. Much of this is actually taken up by phytoplankton, microscopic plants living in the upper waters. It has been suggested that the ocean’s capacity as a carbon sink could be expanded by ‘fertilising’ the oceans with iron. Phytoplankton need iron to grow, but this metal is hard to come by in the ocean, limiting the plankton numbers and therefore the total amount of carbon they can remove from the atmosphere. Trials have shown that adding iron to the water boosts phytoplankton populations, which take up more CO2 as their numbers increase. The wider consequences of iron fertilisation are however unknown and will need to be investigated before this technology can be applied on a larger scale.
