Ocean Iron Fertilization Experiments: Past–Present–Future withIntroduction to Korean Iron Fertilization Experiment in theSouthern Ocean (KIFES) Project

Abstract. Since the start of the industrial revolution, human activities have caused a rapid increase in atmospheric CO 2 concentrations, which have in turn been cited as the cause of a variety climate changes such as global warming and ocean acidification. Various approaches have been proposed to reduce atmospheric CO 2 concentrations. The u0027u0027Martin (or Iron) Hypothesisu0027u0027 suggests that ocean iron fertilization (OIF) should be an efficient method for stimulating the biological pump in iron-limited high nutrient-low chlorophyll regions. To test the Martin hypothesis, a total 13 OIF experiments have been performed since 1990 in the Southern Ocean (7 times), in the subarctic Pacific (3 times), in the equatorial Pacific (twice), and in the subtropical Atlantic (once). These OIF field experiments demonstrated that primary production could be significantly increased after artificial iron addition. However, export production efficiency revealed by the OIF experiments was unexpectedly low compared to production from natural processes in all, except one of the experiments (i.e., the Southern Ocean European Iron Fertilization Experiment, EIFEX). These results, including side effects such as N 2 O production and hypoxia development, have been scientifically debated amongst those who support and oppose OIF experimentation. In the context of increasing global and political concerns associated with climate change, it is valuable to examine the validity and usefulness of the OIF. We provide a general overview of the OIF experiments conducted over the last 25 years (past), a discussion of OIF considerations including possible side effects (present), and an introduction to the OIF experiment plan currently being designed by Korean oceanographers (future).