A great summary of what appears to be a successful demonstration of geoengineering is linked below. Basically they dumped iron (a necessary nutrient) into the ocean to stimulate a rapid burst of algae growth, then tracked the algae bloom as it sunk (sequestering the CO2 that organisms assimilated through photosynthesis). The original research is here.
I also appreciate their editorial article here. We need an “all of the above” strategy, and we need to understand what can work and what won’t work, so we know what tools we have available, should they be needed. Of course, geoengineering should be a last resort, but when and if we need it, it will pay to have done some basic research in this area.
Victor Smetacek, Christine Klaas, Volker H. Strass, Philipp Assmy, Marina Montresor, Boris Cisewski, Nicolas Savoye, Adrian Webb, Francesco d’Ovidio, Jesús M. Arrieta, Ulrich Bathmann, Richard Bellerby, Gry Mine Berg, Peter Croot, Santiago (2012). Deep carbon export from a Southern Ocean iron-fertilized diatom bloom Nature DOI: 10.1038/nature11229