Iron fertilisation experiment success

Iron fertilisation has been discussed as a possible geo-engineering fix for the planet for some years, but a recent study published in Nature has given the theory some hard evidence to back it up. The EIFEX experiment, carried out in 2004 but only now published, has shown a substantial amount of the carbon sequestered by the algal bloom sunk into long term storage in the deep ocean. It has contradicted another 2009 study entitled LOHAFEX, which found little of the carbon sequestered in that experiment reached the ocean floor.

By adding dissolved iron to the water of the Southern Ocean, phytoplankton growth is stimulated. The team followed the algal bloom formed for five weeks from start to decline. The consequent bloom in this experiment eclipsed those of all previous ones and developed in the deeper ‘mixed’ layer, which is far deeper than it was thought possible for bloom development.

Previous experiments lacked certain nutrients in the water, which prevented the same type of growth. It is the first time the technique has shown any real success in terms of sequestering large amounts of carbon. "We were able to prove that over 50 per cent of the plankton bloom sank below 1000 metre depth indicating that their carbon content can be stored in the deep ocean and in the underlying seafloor sediments for time scales of well over a century," says Prof. Victor Smetacek who worked on the project.

Iron plays an important role in the oceans, as photosynthesis relies on the metal. In the past, during dryer periods of the Earths past, far more iron was transported into the oceans than during the present day, making carbon uptake into the ocean higher. This experiment is effectively simulating that.

The failure of other experiments shows the importance of finding the precise conditions required for carbon sequestration, and this research could mean that the technique is a viable geo-engineering tool in the effort to reduce atmospheric carbon dioxide. Some estimates put a global iron fertilisation plan at only $20 billion, others at about $2 per tonne of carbon. This puts the technique as one of the cheapest methods to reduce carbon dioxide that has yet been devised. It is of course still in the early stages of development as a technology, and with further research could yet become a viable means to prevent dangerous climate change.