Surprises from the ocean: Marine plankton and ocean pH
The world's oceans support vast populations of single-celled organisms (phytoplankton) that are responsible, through photosynthesis, for removing about half of the carbon dioxide that is produced by burning fossil fuels as much as the rainforests and all other terrestrial systems combined. One group of phytoplankton, known as the coccolithophores, are known for their remarkable ability to build chalk (calcium carbonate) scales inside their cells, which are secreted to form a protective armour on the cell surface. On a global scale this calcification process accounts for a very significant flux of carbon from the surface ocean, and hence coccolithophores are an important component of the global carbon cycle, as cells die and the calcium carbonate sinks to form ocean sediments.