This plan might have merits:
They propose that vertical pipes some 10 metres across be placed in the ocean, such that wave motion would pump up cool water from 100-200 metres depth to the surface, moving nutrient-rich waters in the depths to mix with the relatively barren warm waters at the ocean surface.
This would fertilise algae in the surface waters and encourage them to bloom, absorbing carbon dioxide greenhouse gas while also releasing a chemical called dimethyl sulphide that is know to seed sunlight reflecting clouds.
"Such an approach may fail, perhaps on engineering or economic grounds", they say, adding that the effects on the acidity of the ocean also have to be factored in.
While the technique is different the actual aim is very similar to the iron fertilization proposed by Planktos. One other difference, this is proposed by James Lovelock and the past head of the British Antarctic Survey, while Planktos are mere money grubbing capitalists. Shouldn\’t matter, of course, a good idea is a good idea, wherever it comes from, but sadly it does matter.
Certainly it\’s something that might be tried. The basic idea is the same as growing forests: more CO2 is going into the atmosphere than current levels of biomass can sequestrate. So let\’s increase the amount of biomass doing the sequestrating.
Whether it will actually work is another thing, but then that\’s what experiments are for, isn\’t it?
Update. As William says, looks like experimentation won\’t be necessary. Crackpot idea (100 million 200 ft long plastic tubes?).