Thanks for the link. That particular guy is on the wacky side, but Iron Fertilization, the core of his proposal, does have some promise and is being studied. However it faces the same major issues that any geoengineering endeavor, like injecting aerosols, does, we have no way of understanding the total environmental impact of such drastic actions.

Iron Fertilization is definitely a bit different from throwing mud into the sea and growing water forests, but yeah, there is potential promise and hopefully an advanced enough might be able to calculate the risks that we cannot.