Iron dust dumped in ocean to combat global warming?

Question

I read an article about a company that was being pro-active in the whole global warming thing and was dumping tons (literally) of iron dust in the ocean. This sounds wacky to me. I don't understand how this could help and what type of negative impact could this have?

Answer 1

Guessing the company is Planktos.  

Apparently, the iron is a critically scarce element, which prevents growth of planton (tiny floating green plants which absorb carbon dioxide).  

Skeptic argue that much of the absorbed carbon makes its way back into the atmosphere, while proponents argue that it is an extremely efficient way to capture carbon.  

Ideally, the carbon becomes calcium caronate, and sinks to the ocean floor and is sequestered; or becomes nutrients which enter the food chain and feeds (ultimately) people.

Answer 2

The idea is that it would encourage plankton blooms to form which would have two knock on effects. The first would be the absorption of Carbon dioxide via the growth of the blooms, taking it out of the atmosphere. The second would be the release of dimethyl sulphide (DMS) into the atmosphere which acts as condensation nuclei for clouds which result in a greater portion of incoming solar radiation being reflected back into space, cooling the climate.

In terms of negative impact, increased plankton would draw other nutrients for the ocean, negatively affecting other marine life. DMS also oxidises into Sulphur dioxide in the atmosphere which when mixed with water forms sulphurous acid (oxidising further to sulphuric acid which is a stronger acid), resulting in acid rain.

Answer 3

I don't have the sources on hand right now, but i'm pretty sure the science behind that company's proposal has been debunked.  If i find a source i'll add it later.