Iron Fertilization of Oceans is Proposed to Absorb CO2

Scientists at Woods Hole Oceanographic Institution (WHOI) have hosted an international, interdisciplinary conference to discuss the proposal of spreading slurries of dissolved iron into the oceans in order to "fertilize" the waters.

The proposed "iron fertilization" would promote vast blooms of phytoplankton, which are a species of marine plant. Scientists and engineers have proposed fertilizing the ocean as a means to combat rising concentrations of greenhouse gases in the atmosphere.

The mechanism at work behind the proposal is that phytoplankton consume carbon dioxide (CO2) as they grow. This growth can be stimulated in certain ocean basins by the addition of iron, which is a necessary micronutrient for phytoplankton growth.

The relevant theory is that if you make such carbon-dioxide consuming phytoplankton blooms large enough, you could remove excess CO2 from Earth's atmosphere. Once removed, it would be carried down into the deep ocean since all organic matter in the ocean sinks, as do fecal pellets and dead plankton.

The accumulation and subsequent sinking of the organic matter which is CO2 would thus reduce the impact of green house gasses and global climate warming.

Dissolved iron is common on land, although it is often rare in the ocean: dissolved iron is often not an element naturally found in ocean waters. Some researchers and commercial interests have recently proposed to introduce this missing nutrient, and that on a large scale, in order to create artificial phytoplankton blooms.

Scientists took a serious interest in the idea in the late 1980s after oceanographer John Martin famously (or infamously) told colleagues in what was said to be a Dr. Strangelove-type voice: "Give me half a tanker of iron and I'll give you the next ice age." The implication being that so much phytoplankton would be produced and so much CO2 absorbed that global temperatures would plummet, which is a reference to Antarctic ice core samples that show a correlation between CO2 and temperature.