Australian biologists have estimated that about,

”12,000 sperm whales in the Southern Ocean each defecate around 50 tonnes of iron into the sea every year after digesting the fish and squid they hunt.   The iron is a terrific food for phytoplankton – marine plants that live near the ocean surface and which suck up CO2 from the atmosphere through photosynthesis.”

Those Japanese whalers and their Norwegian cousins have a lot to answer for.  Can’t help think Greenpeace are missing a trick.