Iron is recognised as a nutrient, the lack of which limits plankton growth in some parts of the ocean. By adding small quantities of iron to the surface of the ocean, plankton growth can be stimulated (‘the iron hypothesis’), potentially providing a means of extracting carbon dioxide from the atmosphere and sequestering it in the deep ocean for hundreds of years.
Over the past two decades, several small-scale iron fertilisation experiments (involving the release of just a few tonnes of iron) have been performed by various institutions across the world. These have helped us understand the basic science of the role of iron in the ocean and in plankton production processes.
Since the advent of the iron hypothesis, it has been recognised that some of the carbon incorporated into the bodies of plankton as they grow would sink into the deep sea (e.g., to depths greater than 1000 m), or even onto the seafloor. Achieving this operationally to have an impact climate would require the release of very large quantities of iron into the sea, over large areas and over very long periods of time. Iron fertilisation used in this way would be a form of ‘geo-engineering’ the planet. There are known to be potentially serious side effects including disrupting marine ecosystems, making the oceans more acidic, depleting dissolved oxygen and producing other greenhouse gasses as a by-product.
To test whether iron fertilisation as a form of geo-engineering would work and to understand its side effects would require larger-scale, longer-duration experiments than the small-scale experiments conducted to date. However, undertaking large-scale experiments (involving hundreds or thousands of tonnes of iron) would be controversial. In particular, there would be a number of complex legal, ethical, political, economic and regulatory issues associated with large-scale operational iron fertilization and some of these may also apply to large-scale experiments at sea.
On 21 June 2010, The Times and subsequently The Telegraph reported that the National Oceanography Centre (NOC) was planning to undertake a large-scale iron fertilisation experiment.
The conversation with a scientist that resulted in the original Times article on large-scale geo-engineering experiments was purely speculative. There is currently no plan involving the National Oceanography Centre or its owner the Natural Environment Research Council (NERC) to fund or undertake any experiment of the nature and scale as that outlined in the piece.
A number of factors influence our approach:
- A recent report by the Royal Society (Geo-engineering the Climate: Science, Governance and Uncertainty, September 2009) evaluated a large range of potential geo-engineering options. Iron fertilisation did not emerge as one of the more promising options against a variety of criteria and is not therefore a present priority for research investment;
- NERC has been engaged in public dialogue concerning the general principles of geo-engineering research. An early finding has been public concern about approaches that involve the marine environment. Consequently, if work on large-scale iron fertilisation were to be contemplated, then we would engage in further public dialogue, especially as we are already aware of the complex societal issues that are entailed in the approach;
- Ahead of any large-scale experiment more research, such as simulations using computer models, would be necessary.
The National Oceanography Centre takes the view that informing developments of geo-engineering concepts, including iron fertilisation, with sound theoretical and experimental science is an appropriate activity consistent with our mission; but all activity in which NOC participates must be within the framework of national and international regulations and conventions concerning iron fertilisation.
Consequently, NOC is prepared to participate in theoretical and initial desk and preparatory studies and does not rule out continuing to participate in iron fertilisation experiments, which are relevant not only to geo-engineering, but also to understanding the fundamentals of ocean biogeochemical processes.
However, in the event of any large-scale experiment being proposed, whether funded by NERC or not, we would consult the relevant NERC Boards including those concerned with ethical matters and continued participation would be contingent on the outcome.
In any event, geo-engineering solutions are not a substitute to the primary need to cut emissions.