I hadn't previously encountered this idea.
Within weeks, the ship's crew hope to dump 20 tonnes of ferrous sulphate into the Southern Ocean. Plankton need iron to grow, and the aim of the expedition is to trigger a plankton bloom and boost the amount of carbon that is sucked out of the air and locked up at the bottom of the ocean.
The team, led by Victor Smetacek of the Alfred Wegner Institute, Bremerhaven, Germany, will also monitor the population of krill to see if their populations also increase. These small crustaceans feed on plankton and are an important food source for many marine species. So, if the population grows, this could give fisheries a boost.
It's not unopposed.
If this iron dump goes ahead it will be in clear defiance of the UN Convention on Biological Diversity," warns Jim Thomas of ETC Group. The CBD resolution makes an exception only for small coastal experiments, but Smetacek says his expedition has been approved by the German environment ministry.
It sounds like a big operation, but expectations should be kept low.....
"Twenty tonnes of iron particles in the vast ocean is very much drop in the bucket and is unlikely to have a lasting effect," says Ken Caldeira of Stanford University. "The rational concern is that experiments will lead down some slippery slope - that small experiments could be scaled up without any regulation."
Ocean fertilisation and other geoengineering schemes, says Caldeira, should be seen as potential short-term solutions that could cool temperatures while humans switch to non-fossil sources of energy.