Giga bites

commercial fertilization of the oceans, which could emerge as a new way for fuel-guzzling countries to engineer their carbon balance. Particularly, they criticize the size of the project, and the fact that it is located in the open ocean, while an international convention that Gabriel helped to set up in 2008 specifies that such experiments are only permissible for fundamental research, on a small scale, and in coastal waters. The last of these conditions is controversial in itself, as coastal waters will be more vulnerable to any ecological damage caused. The researchers on the project feel that they satisfy the spirit of this clause, however, in conducting their experiment in waters that have previously passed the coasts of South America and are therefore rich in organisms that can use up the extra iron quite rapidly. As for the scale of the project, size is always a relative matter. Lohafex researchers argue that, at an average diameter of 20 km, the region exposed to the extra iron will be much smaller than a typical vortex in the ocean currents of that area. It will also be smaller than the areas affected by the natural equivalent of the process, the dissolution of an iceberg breaking off from the Antarctic shelf. As for the amount of iron sulphate released, 20 tonnes of iron sounds like a lot, but spread out over 300 square kilometres, this yields only 70 milligrams of iron per square metre. As the debate heated up towards the end of January, the research ministry temporarily blocked the experiment pending further reviews. On January 26th, the research minister Annette Schavan gave the definite go-ahead, based on three additional expert reviews. It is also understood that the chancellor, Angela Merkel, who risked losing face over the agreement she signed, was strongly in favour of allowing the experiment to go ahead. Gabriel’s environment ministry responded with a press release emphasizing its continued disapproval. The only thing that both ministries seem to agree on is that they don’t want commercial-scale fertilization to become a reality. Pouring water on the concerns of the skeptics, a research paper based on the earlier Crozex project, which observed a natural iron boost that happened in the Southern Ocean in 2004–2005, reported a carbon sequestration efficiency that was 77 times smaller than the value previously reported from another ironinduced bloom (Nature (2009) 457, 577). While undermining the case for climate engineering, the data seem to suggest that the outcome of iron fertilization is very sensitive to the conditions under which it takes place, and that more detailed research — like Lohafex — is needed to better understand these processes. Meanwhile, out in the South Atlantic, the 49 researchers on board Polarstern have approached the area of interest and selected a precise location for the experiment, based on satellite imaging of ocean currents. After inspecting three separate eddies, the ship returned to ‘eddy 1’, located east of the target area, which had the desirable ‘closed core’ enabling the researchers to conduct the experiment within well-defined limits. By the time the research ministry’s final approval came through, the crew had already pinned down the centre of eddy 1. Immediately after the goahead on January 26, the crew started recording baseline data and filling the tanks with iron sulphate solution. The release of the solution started the following day, proceeding in concentric circles from the centre of the eddy, and covering a total surface area of 300 square kilometres. As the relevant water layer was only half as deep as expected, the crew only released 10 tonnes of iron sulphide instead of the planned amount of 20 tonnes. During the 45 days of measurement time, the scientists led by principal investigators Wajih Naqvi and Victor Smetacek are hoping to clarify many specific details of the algal bloom induced by the iron fertilization, including the species distribution of the algae that first benefit from it, the impact on the krill population and the wider food web, and the actual amount of carbon sequestration achieved by sedimentation of organic material. On-board instruments measure dozens of parameters, including the concentration of nutrients, dissolved gases, organic carbon, trace metals and the oxygen:nitrogen ratio of the seawater. Primary productivity is assessed by on-board incubation of samples that will later be analyzed at the laboratory in Goa, India. The molecular ecology research group on board the ship uses modern technologies like FISH (fluorescence in situ hybridization) to gain insights into the bacterioplankton composition and epifluorescence microscopy to determine cell counts and FISH counts. The mission will officially end in early April when the Polarstern arrives in Punto Arenas, Chile, to get ready for other, probably less controversial, projects.