"I think we are seeing the last gasps of ocean iron fertilisation as a carbon storage strategy," says Ken Caldeira of the Carnegie Institution at Stanford University.

Let's say you want to seed the ocean bottom with iron as an carbon storage mechanism to fight global warming. Sorry, nature won't let you. That darn food chain thing gets in the way. There is probably a speculative fiction story here. I thought of it first, but I'm busy with my translation of Beowulf into Vulcan.