Ocean storage of carbon dioxide ocean waters in order to increase carbon dioxide (CO2) uptake from the atmosphere, possibly resulting in mitigating its global warming effects. Iron is a trace element in ocean and its presence is vital for photosynthesis in plants, and in particular phytoplanktons, as It has been shown that iron deficiency can limit ocean productivity and phytoplankton growth. For this reason, “iron hypothesis” was put forward by Martin in late 1980s where he suggested that changes in iron supply in iron-deficient ocean-waters can bloom plankton growth and have a significant effect on the concentrations of atmospheric carbon dioxide by altering rates of
Carbon dioxide removal to the biosphere. This process could be undone, for example by wildfires or logging. Carbon dioxide sinks that store carbon dioxide in the Earth's crust by injecting it into the subsurface, or in the form of insoluble carbonate salts (mineral sequestration), are considered carbon negative. This is because they are removing carbon from the atmosphere and sequestering it indefinitely and presumably for a considerable duration (thousands to millions of years). However, Carbon Capture technology remains, at best, theoretical and is yet to reach more than 33% efficiency. Furthermore, this process could be rapidly undone, for example by earthquakes or mining.