Ocean fertilization

Ocean fertilization or ocean nourishment is a type of climate engineering based on the purposeful introduction of nutrients to the upper ocean to increase marine food production and to remove carbon dioxide from the atmosphere. A number of techniques, including fertilization by iron, urea and phosphorus have been proposed. John Martin, director of the Moss Landing Marine Laboratories, hypothesized that the low levels of phytoplankton in these regions are due to a lack of iron. To test this hypothesis (known as the Iron Hypothesis) he arranged an experiment using samples of clean water from Antarctica. Iron was added to some of these samples. After several days the phytoplankton in the samples with added iron grew much more than in the untreated samples. This led Martin to speculate that increased iron concentrations in the oceans could partly explain past ice ages. This experiment was followed by a larger field experiment (IRONEX I) where 445 kg of iron was added to a patch of ocean near the Galápagos Islands. The levels of phytoplankton increased three times in the experimental area. The success of this experiment and others led to proposals to use this technique to remove carbon dioxide from the atmosphere. In 2000 and 2004, iron sulfate were discharged from the EisenEx. 10 to 20 percent of the resulting algal bloom died and sank to the sea floor. Planktos was a US company that abandoned its plans to conduct 6 iron fertilzation cruises from 2007 to 2009, each of which would have dissolved up to 100 tons of iron over a 10,000 km2 area of ocean. Their ship Weatherbird II was refused entry to the port of Las Palmas in the Canary Islands where it was to take on provisions and scientific equipment. In 2007 commercial companies such as Climos and GreenSea Ventures and the Australian-based Ocean Nourishment Corporation, planned to engage in fertilization projects. These companies invited green co-sponsors to finance their activities in return for provision of carbon credits to offset investors’ CO2 emissions. LOHAFEX was an experiment initiated by the German Federal Ministry of Research and carried out by the German Alfred Wegener Institute (AWI) in 2009 to study fertilization in the South Atlantic. India was also involved. As part of the experiment, the German research vessel Polarstern deposited 6 tons of ferrous sulfate in an area of 300 square kilometers. It was expected that the material would distribute through the upper 15 metres (49 ft) of water and trigger an algal bloom. A significant part of the carbon dioxide dissolved in sea water would then be bound by the emerging bloom and sink to the ocean floor.