OK, So It Wasn't Quite That Easy...

John Martin said "Give me a half tanker of iron, and I'll give you the next ice age."  A new study suggests it won't be sufficient.

An Indian-German group tried with a tanker load of iron solution. Instead of the iron stimulating phytoplanton growth, sucking CO2 from the atmosphere,dying and sinking to the bottom, sequestering many time its weight in carbon, the bloom that formed stimulated a massive copepod bloom, which devoured the algae and kept most the carbon in the surface ocean where it can easily be recycled in the atmosphere.

Earlier this month, the controversial Indian-German Lohafex expedition fertilised 300 square kilometres of the Southern Atlantic with six tonnes of dissolved iron. The iron triggered a bloom of phytoplankton, which doubled their biomass within two weeks by taking in carbon dioxide from the seawater. Dead bloom particles were then expected to sink to the ocean bed, dragging carbon along with them.

Instead, the bloom attracted a swarm of hungry copepods. The tiny crustaceans graze on phytoplankton, which keeps the carbon in the food chain and prevents it from being stored in the ocean sink. Researchers from the Alfred Wegener Institute for Polar and Marine Research reported that the copepods were in turn eaten by larger crustaceans called amphipods, which serve as food for squid and fin whales.

Now, I knew John Martin, a little. A very, very smart man.  I don't think for a minute he thought that all the phytoplankton would die and sink to the bottom.  Even back when I was in grad school, and John was at the top of the heap among biogeochemists, it was pretty well dogma that production at the sea surface was moved downward in an exponential, even double exponential decline, with multiple ecosystems taking a "bite of the apple"   Even copepods shit, as do squid and whales, and those little particles (or big as the case may be) sink further faster than the original plankton. And dead whales mostly sink, carrying that carbon to the bottom, out of circulation with the atmosphere for a long time. So even if the immediate end of the new carbon is copepods, it doesn't mean that some fraction of the new production stimulated by the iron will not end up on the ocean floor.

IMHO, John was indulging in a bit of creative hyperbole, creating a bit of interest in the science that he cared deeply about, and perhaps suggesting a method of fine tuning the climate through geoengineering should we ever understand it well enough to attempt it.