Oceanic iron fertilization involves dumping enormous amounts of iron sulfate into wide expanses of the ocean. Theoretically, it would stimulate the growth of phytoplankton, the tiny sea life that absorbs carbon dioxide, releases oxygen, and is gobbled up by other creatures. This is key, because every year the ocean absorbs about a quarter of the carbon dioxide we emit into the atmosphere, changing the chemistry of the oceans and harming marine ecosystems. At the University of the South Pacific in Fiji, researchers are exploring how kelp forests and other seaweed habitats in the ocean could suck up carbon.