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Published: January 31, 2011

Policy summary published on controversial geoengineering scheme, ocean fertilization

Press release |

Geoengineering schemes involving ocean fertilization to affect climate have a low chance of success, according to the first summary for policymakers on the issue.

Ocean Fertilization: summary for policymakers
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Ocean Fertilization: summary for policymakers

Failure to tackle rising greenhouse gas emissions effectively has led to intensifying debate on geoengineering - deliberate large-scale schemes to slow the rate at which Earth is heating up. The public debate often mixes opinion with fact so scientists have now released the first summary for policymakers on ocean fertilization, one of the earliest geoengineering proposals. The authors report that the chances of success of using ocean fertilization to deal with climate change is low.

Ocean fertilization involves adding iron or other nutrients to the surface of the ocean to trigger growth of microscopic marine plants.  These plants use dissolved carbon dioxide to grow, which led to the idea that deliberate fertilization of the ocean on a large scale would remove carbon dioxide from the atmosphere.  

Lead author of the report Professor Doug Wallace from the Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR) says: "The published findings suggest that even very large-scale fertilization would remove only modest amounts of carbon dioxide from the atmosphere over 100 years".

For two decades, marine scientists have been carrying out a series of small-scale fertilization experiments to understand how ocean ecosystems respond to environmental change. However the experiments were not designed to address issues relating to geoengineering. Proposals to scale up this approach to slow climate warming or be included within emissions trading schemes to generate carbon credits have stimulated intense debate and criticism amongst scientists and the public.

The new summary, involving independent scientists from seven countries, explains the complexity of the underlying science and brings the detailed findings together in an accessible form for policymakers.

The summary notes that there are still major knowledge gaps. For example, it is unclear whether findings from small-scale experiments apply fully to larger scales. And a major concern is the possibility of large-scale fertilization having unintended consequences for ecosystems. The summary points out the extreme difficulty of assessing long-term effectiveness or unintended side effects.

"It's vastly more complex than assessing carbon storage in a forest" says Wallace "the carbon, and many of the potential impacts, are largely invisible and likely to be spread over vast distances".

Publication of the summary coincides with a symposium in California (La Jolla) on the ecosystem impacts of proposed geoengineering schemes and organized by the International Geosphere-Biosphere Programme. The one-day symposium, streamed live online, will bring together the world's leading experts in this area of research.


Ocean fertilization: a summary for policy makers
Published by: Intergovernmental Oceanographic Commission (IOC), which is part of UNESCO.   Document  prepared with the assistance of the Surface Ocean Lower Atmosphere Study (SOLAS), an international programme that focuses research effort on air-sea interactions and processes, sponsored by the International Geosphere-Biosphere Programme (IGBP), the Scientific Committee on Oceanic Research (SCOR), the World Climate Research Programme (WCRP) and the International Commission on Atmospheric Chemistry and Global Pollution (ICACGP).
The summary for policymakers is available here:


D.W.R. Wallace, C.S. Law, P.W. Boyd, Y. Collos,
P. Croot, K. Denman, P. Lam, U. Riebesell, S. Takeda &
P. Williamson; Ocean Fertilization. A Scientific Summary for Policy

Makers. IOC/UNESCO, Paris 2010. IOC Brochure 2010-2

Authors: Doug Wallace (IFM-GEOMAR, Germany), Cliff Law (NIWA, New Zealand), Philip Boyd (University of Otago, New Zealand), Yves Collos (CNRS Université Montpellier, France), Peter Croot (PML, UK), Ken Denman (Fisheries & Oceans, Canada), Phoebe Lam (WHOI, USA), Ulf Riebesell (IFM-GEOMAR, Germany), Shigenobu Takeda (Nagasaki University, Japan) and Phil Williamson (NERC, UK).

Geoengineering symposium, 31 January 2011
IGBP holds a symposium on the ecosystem impacts of geoengineering on 31 January, 8:30am-8:30pm, at the Scripps Institution of Oceanography, California. The symposium can be watched live online.
See http://aerosol.ucsd.edu/IGBPworkshop for more details.

More information

Owen Gaffney
Director of communications
International Geosphere-Biosphere Programme
Email: owen.gaffney@igbp.kva.se
Tel: +46 86739556
Mob: +46 730208418
Skype: owengaffneyigbp

Phil Williamson
School of Environmental Sciences
University of East Anglia
Norwich NR4 7TJ
Tel: +44 (0)1603 593111
Mob: +44 (0)7749 092 287

Douglas Wallace
Chemische Ozeanographie
FB Marine Biogeochemie
Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR)
Email: dwallace@ifm-geomar.de
Tel. 49-(0)431-600-4200 (4201)

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