Meddling with the Oceans?

A report in the science journal Nature describes experiments to add iron to oceans, in order to boost plankton which capture carbon dioxide, and store the carbon at the bottom of the ocean when they die.

http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/7856144.stm

The idea is to use this system as a form of 'artificial eco-engineering' to help curb climate change.
However, small-scale scientific experiments to research these mechanisms is one thing, using the technique wholesale to change the climate is something else altogether. GM crops and 'a step too far' spring to mind. The natural eco-system and bio-diversity are complex and delicately balanced, having evolved over countless aeons. A bull-in-a-china-shop approach is unwise, to say the least.