The CICS Science group is working with GFDL through CICS to maintain a group of scientists able to analyze mitigation options as they arise. While iron fertilization and deepsea injection do not appear to be gaining traction as viable options, there does continue to be strong interest in them, including amongst private commercial ventures. There are many unresolved questions that are of considerable interest scientifically, and the outcomes will have significant impact on our evaluations of the viability of these options.
Sarmiento’s group has carried out a new set of iron fertilization simulations making use of the new generation of ecosystem and iron chemistry models that have been developed over the past decade at Princeton and GFDL. These new fertilization model results differ significantly from the major conclusions of our previous research by Gnanadesikan in showing much greater sequestration efficiency. The main reason for this is that the added iron is retained for a long period of time in the models and thus continues to draw carbon down each time it returns to the surface. In previous research, it had been assumed that the added iron would be scavenged very rapidly.\
Two additional types of simulations have been performed. The first includes a simple global atmosphere for carbon. This reduces the efficiency of the carbon uptake by about 40% due to decreased uptake elsewhere in the ocean. The second simulation is designed to use the added iron only once before it is lost from the system. This simulation reduces the amount of carbon removed from the atmosphere by iron fertilization by up to a factor of 10 over the case where iron is allowed to be retained.