Was The Great White Fleet A Bully Iron Experiment ?
Ever since oceanographer John Martin launched the ocean fertilization controversy two decades ago by asserting : "Give me a half tanker of iron and I'll give you an ice age," ecologists have warned the impacts on marine food webs might not be worth the risk. The subject is hotly, and at times bitterly debated from coast to coast-- Woods Hole to Scripps Institute to be exact, but that has not stopped boiler room operators from offering dubious carbon offsets based on little more than promises to drop scrap iron in the ocean. SEC oversight scarcely applies to such penny stock science, the supposed benefits being calculated from the paper ratio of iron in biomass to the weight of whatever may be thrown over the transom.
The subject deserves better, and
it got a cautionary hearing at this fall's bioengineering conference at the American Academy of Arts and Science in Cambridge. While marine biologists and ecologists remain skeptical of current proposals to capture carbon by fertilizing the oceans, it's clear from small scale experiments that the effect is real, albeit hard to quantify, since plankton blooms sink and disperse, and other elements are equally if not more important as marine fertilizers. Yet it could be that the late Dr.Martin's wish for large-scale experiments was realized before he was born, with the equivalent of many shiploads of iron being dispersed at sea .
The biogeochemical cycle of iron continues today as always, with the wind-born deposit of tonnes of metal bearing dust far out to sea. Could early 20th century shipping practice have altered marine biochemical equilibrium in a similar fashion, as steamers emulated Saharan dust storms in spewing iron downwind, and down current, far out at sea ? If so, there may have been radical decline in iron deposition in some mid-ocean waters as bunker oil replaced bunker coal as the mainstream marine fuel.
Burning coal typically generates ash equal to a tenth the weight of
the fuel. In modern power plants electrostatic
precipitators, baghouses, and
scrubbers remove over 95% of such particles. Steamships had none of
these bulky gadgets, and most of their ash flew up the smokestacks and
into the drink.
A 50,000,000 ton fleet of coal fired steamships existed less than a
century ago. Owing to coals low energy density a ship's annual
consumption often exceeded its
registered tonnage. Though highly efficient for its day, the Titanic
consumed nearly a kiloton of coal daily, and ordinary Edwardian vessels
typically ate their weight in bunker coal in a month underway. This
created enormous demand
Europe alone supplying 213 million tons of bunker coal in 1913- enough
to make a pile the size of an iceberg, but only half the world total ,
or perhaps less- -the numbers are obscure, for Cunard nostalgia
notwithstanding, coal studies are not the height of scientific fashion.
Coal ash typically contains a scant hundred pounds of iron per ton.
Much comes from burning iron pyrites( FeS2), and acid sulfur gases in
the exhaust of a coal fired steam boiler may have enhanced fly ash as
ocean fertilizer by turning rusty oxide particles into soluble
sulfates. Lord knows modern coal carriers complain of bilge corrosion.
With roughly a megaton of iron being released at sea annually, the early 20th century may have witnessed a heavy aerosol iron flux along well traveled shipping lanes. Could this have given ravenous phytoplankton and algae in mineral deficient 'marine desert ' regions a continuous series of square meals, and made the ocean bloom in the wake of Teddy Roosevelt's White Fleet ?
Studying the quantities and composition of coal combusted along historic shipping lanes could shed some light on the risks and benefits of the experiments being proposed today, and perhaps help illuminate why 20th century temperature rises fall near the low end of what many climate models predict. It remains to be discovered if the post-Victorian expansion of free trade by sea was not a great green experiment in disguise, but I suspect TR would have pronounced it a bully idea had Gifford Pinchot suggested the fleet take along a plankton net wielding oceanographer, and a few extra bottles of alcohol, for preservative purposes only.