IT IS another nail in the coffin of ocean fertilisation for cooling the planet. Early results from the latest field experiment suggest the technique will fail. 鈥淚 think we are seeing the last gasps of ocean iron fertilisation as a carbon storage strategy,鈥� says of the Carnegie Institution at Stanford University in California.
The controversial Indian-German LOHAFEX expedition fertilised 300 square kilometres of the Southern Atlantic with 6 tonnes of dissolved iron. Sure enough the iron triggered a bloom of phytoplankton. Dead bloom particles were then expected to sink to the ocean bed, dragging carbon along with them.
Instead, the bloom attracted a swarm of hungry copepods. The tiny crustaceans graze on phytoplankton, which keeps the carbon in the food chain and prevents it from being stored in the ocean sink. The copepods were in turn eaten by larger crustaceans called amphipods, which serve as food for squid and fin whales.
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鈥淚t seems that if it is possible to fertilise enough ocean to make a difference to climate, we would need to turn vast ocean ecosystems into giant plankton farms,鈥� says Caldeira.