Ocean fertilisation using iron is a geo-engineering technique that aims to artificially stimulate the biological carbon pump.
Principle of ocean fertilisation
This technique consists in seeding zones of the oceans that are low in biomass with nutrients to limit the development of this biomass. Iron is used most often. During experiments, boats have therefore poured tonnes of iron into these areas to cause an efflorescence of phytoplankton.
These organisms are supposed to bind CO2 by photosynthesis and transfer it towards the ocean depths by sedimentation of the organic matter, similar to what occurs in oceanic zones that are rich in biomass. The theory is that the fertilisation operation thus stimulates the biological carbon pump where it is not very active.
Questions on this technique
However, as with most geo-engineering attempts, the economic feasibility and effectiveness of this technique are uncertain, as are its side effects on ecosystems and the environment.
A phytoplankton bloom resulting from the natural fertilisation of the Oman Sea by sandstorms rich in iron. © Nasa / GSFC / LaRC / JPL, MISR Team
Ocean fertilisation - 1 Photo