The tiny organisms need minerals like iron to grow and multiply, but there's only a fixed amount floating at the surface of the waters with them, which limits how much phytoplankton can bloomSeeding the oceans with nano-scale fertilizers could create a much-needed, substantial carbon sink.
This poetic completion of the cycle we've broken could sequester this carbon for hundreds of thousands of years, as the fossils-turned-fuel did before them. Reviewing 123 studies, University of Leeds biogeochemist Peyman Babakhani and colleagues found some engineered nanoparticles that might be candidates for safely fertilizing phytoplankton growth.
, rather than concentrations, so it could be released at levels equivalent to those already in the seawater.
One problem with this is that the phytoplankton release methane as they decompose, which is a 28x more powerful greenhouse gas than the CO₂ removed. This is an old idea.