would stay isolated from the atmosphere. Furthermore, there is considerable uncertainty about the impact of these manipulations on marine ecosystems and the services they provide to society, particularly since CO2 causes ocean acidification, which is expected to harm marine ecosystems. Much effort has been focused on trying to protect marine ecosystems by keeping CO2 out of the ocean, whereas ocean fertilization proposals seek to do the opposite. Because large parts of the oceans are a global commons, regulation of such activities represents a significant issue that has yet to be addressed. Furthermore, verification of amounts of carbon stored by ocean fertilization activities would be challenging, at best.
In summary, it is feasible that human manipulation of marine ecosystems could store at least some extra CO2 in the oceans. While maximum storage rates are projected to be at most a few percent of total human-generated GHG emissions, significant questions remain regarding exactly how much carbon could be stored, and for how long, using these approaches. Furthermore, considerations such as ocean acidification and the difficulty of predicting responses of marine ecosystems make it doubtful whether such manipulations could contribute to overall environmental risk reduction.
Improve understanding of the effects of climate change and impacts of enhanced CO2on ecosystems, ecosystem services, and biodiversity. Given the complexity of the impacts of different scenarios of climate change and elevated CO2 levels on ecosystem function, services, and biodiversity, further research is needed to evaluate the consequences of multiple interacting changes. For example, movement of species, changes in phenology and synchronicity, changes in productivity and carbon cycling processes, and changes in disturbance regimes in response to temperature, moisture, and CO2 have not been well assessed, especially at regional scales. Enhanced capacity for linking models of physical change in the climate system to species response models would help meet these challenges. Research is also needed to identify those ecosystems, ecosystem services, species complexes, and people reliant on them that are most resilient or most vulnerable (see Box 9.2).
Evaluate the climate feedbacks from changes in ecosystems and biodiversity. Changes in ecosystem biogeochemical processes (including GHG emissions) and biodiversity (including changes in reflectance characteristics) have the potential to exacerbate or offset certain aspects of climate change (i.e., act as feedbacks). Models and experiments that integrate knowledge about ecosystem processes, plant physiol-