Intergovernmental Oceanographic Commission Ocean Fertilization A scientific summary for policy makers Experimental ocean fertilization using ferrous sulphate on UK-German FeeP study, 2004 OCEANFERTILIZATION: action to deliberately increase planktonic production in the open ocean. Fertilization might be carried out over a range of scales for a variety of purposes; it can be achieved by directly adding nutrients, or increasing nutrient supply from deep water, or poten- tially by other means. This report was commissioned by the Intergovernmental Oceano- Design: Eric Loddé graphic Commission (IOC), which is part of UNESCO. It was pre- pared with the assistance of the Surface Ocean Lower Atmosphere Image credits Study (SOLAS), an international programme that focuses research Front cover: effort on air-sea interactions and processes, sponsored by the In- Matt Walkington, NIWA; Glynn Gorick; NASA/SeaWiFS ternational Geosphere-Biosphere Programme (IGBP), the Scien- tific Committee on Oceanic Research (SCOR), the World Climate Inside front cover: Research Programme (WCRP) and the International Commission Philip Nightingale, Plymouth Marine Laboratory on Atmospheric Chemistry and Global Pollution (ICACGP). The drafting of this report benefitted from advice by the secretariat of p 2 (Box 1): World Ocean Atlas (2005); US National the International Maritime Organization (IMO); discussions by the Oceanographic Data Center 2009 Intersessional Technical Working Group on Ocean Fertiliza- tion of the London Convention/London Protocol (LC/LP), in which p 4 (Fig 1) & p 5 (Box 2): Jack Cook, Woods Hole IOC participated; and IOC Member States’ comments, including Oceanographic Institution; also Oceanus rd those made at the 43 session of the IOC Executive Council. p 6 (Fig 2): Philip Boyd and NASA Authors: Doug Wallace (IFM-GEOMAR, Germany), Cliff Law p 9 (Box 3): Philip Boyd, in Encyclopedia of Sustainablility (NIWA, New Zealand), Philip Boyd (University of Otago, New Science & Technology Zealand), Yves Collos (CNRS Université Montpellier, France), p 10 (Box 4) World Ocean Atlas (2009) Peter Croot (Plymouth Marine Laboratory, UK), Ken Denman (Fisheries and Oceans Canada), Phoebe Lam (WHOI, USA), Ulf p 11 (Fig 3): Richard Lampitt Riebesell (IFM-GEOMAR, Germany), Shigenobu Takeda (Nagasaki p 12 (Fig 4): Ken Denman University, Japan) and Phil Williamson (NERC, UK). For bibliographic purposes this document should be cited as: p 13 (Box 5): Doug Wallace DWR Wallace, CS Law, PW Boyd, Y Collos, P Croot, K Denman, p 14 (Fig 5) NASA/Jim Gower, IOS Canada PJ Lam, U Riebesell, S Takeda, & P Williamson: 2010. Ocean Fer- tilization. A Scientific Summary for Policy Makers. IOC/UNESCO, Paris (IOC/BRO/2010/2). 2 OCEAN FERTILIZATION A SCIENTIFIC SUMMARY FOR POLICY MAKERS >1< OCEAN FERTILIZATION context andnd keykey messagesmess Concernern over human-driven human driven climate change London Protocol (LC/LP). (LC/LP) To assist that pro- and the lack of success in constraining green- cess, an overview of our scientific understand- house gas emissions have increased scientific ing is timely. The following headline messages and policy interest in geoengineering − deliber- are considered to represent the consensus view, ate interventions in the Earth’s climate system discussed in greater detail in the main text and that might moderate global warming. Proposed based on assessments of the published litera- approaches involve either removing carbon di- ture and extensive consultations: oxide (CO2) from the atmosphere by biological or chemical means (to reduce the forcing of cli- t &YQFSJNFOUBM TNBMMTDBMF JSPO BEEJUJPOT UP mate change), or reflecting part of the sun’s en- high nutrient regions can greatly increase the ergy back into space (to counteract the forcing, biomass of phytoplankton and bacteria, and by altering Earth’s radiation budget). the drawdown of CO2 in surface water. The scale of these effects depends on physical Here we consider the practicalities, opportunities and biological conditions, and the levels of and threats associated with one of the earliest other nutrients. proposed carbon-removal techniques: large- t #FDBVTFTDJFOUJmDTUVEJFTUPEBUFIBWFCFFO scale ocean fertilization, achieved by adding iron short-term and of relatively small scale, it is or other nutrients to surface waters, directly or in- not yet known how iron-based ocean fer- directly. The intention is to enhance microscopic tilization might affect zooplankton, fish and marine plant growth, on a scale large enough not seafloor biota, and the magnitude of carbon only to significantly increase the uptake of atmo- export to the deep ocean is still uncertain. spheric carbon by the ocean, but also to remove There is even less information on the effec- it from the atmosphere for long enough to provide tiveness and effects of fertilizing low nutrient global climatic benefit. This suggestion grew out regions, either directly or by using mixing de- of scientific ideas developed in the late 1980s, vices. No experimental studies have been based on analyses of natural, longterm climate carried out at the larger spatial and temporal changes (ice age cycles) and experiments that scales envisioned for commercial and geoen- provided new insights into the natural factors that gineering applications. limit ocean productivity, and thereby control the t -BSHFTDBMFGFSUJMJ[BUJPODPVMEIBWFVOJOUFOE- cycling of carbon between sea and sky. ed (and difficult to predict) impacts not only locally, e.g. risk of toxic algal blooms, but Proposals for large-scale application of ocean also far removed in space and time. Impact fertilization have been controversial, attracting assessments need to include the possibility scientific and public criticism. Upholding the of such ‘far-field’ effects on biological pro- precautionary principle, the Convention on Bio- ductivity, sub-surface oxygen levels, biogas logical Diversity (CBD) decided in 2008 that no production and ocean acidification. further ocean fertilization activities for whatever t 8IJMTUNPEFMTDBOCFEFWFMPQFEUPJNQSPWF purpose should be carried out in non-coastal predictions of both benefits and impacts, the waters until there was stronger scientific justi- totality of effects will be extremely difficult − fication, assessed through a global regulatory and costly − to directly verify, with implica- mechanism. tions for the confidence and cost-effective- ness of commercial-scale applications. Such a regulatory framework is now being de- t &TUJNBUFT PG UIF PWFSBMM FGmDJFODZ PG BUNP- veloped, through the London Convention and spheric CO2 uptake in response to iron-based 1 ocean fertilization have decreased greatly (by 5 bly by including comparison with several oth- – 20 times) over the past 20 years. Although erwise similar but non-fertilized regions; and uncertainties still remain, the amount of carbon iii) continue over appropriate time and space that might be taken out of circulation through scales, potentially over several years and cov- this technique on a long-term basis (decades ering many thousand square kilometres. to centuries) would seem small in comparison to fossil-fuel emissions. Fertilization achieved This document focuses on scientific issues. through artificial upwelling is inherently less ef- Whilst socio-economic, ethical and legal consid- ficient for sequestration. erations are also highly important, they are not t .POJUPSJOHNVTUCFBOFTTFOUJBMDPNQPOFOU given equivalent attention here. Where estimates of any large-scale fertilization activity, both to of likelihood or certainty/uncertainty are given, check claims of carbon sequestration (for in- they are intended to be equivalent to definitions tended geoengineering benefit) and to assess used by the Intergovernmental Panel on Climate ecological impacts. Monitoring will need to: Change; however, there has been no formal pro- i) include a wide range of sensitive parameters; cess to quantify risks and probabilities. ii) take into account natural variability, prefera- Limitation of oceanic biological production in high and low nutrient regions 1 box Average levels of available nitrogen (as nitrate, left) and phosphorus (as phosphate, right) in the sur- face ocean Biological production in the ocean usually There are also large areas of the surface refers to growth of planktonic (drifting) micro- ocean – shown above in red, yellow and green organisms that fix carbon by photosynthesis. – where N and P levels remain well above their This requires light and a range of essential limiting concentrations year-round. In these elements or nutrients. Since carbon (C), ni- high nutrient regions, the concentration of trogen (N) and phosphorus (P) are required in iron (Fe) can instead be limiting. Since phyto- relatively large amounts, they are known as plankton need around a thousand times less macro-nutrients. Fe than either N or P, it is known as a micro- nutrient. The amount of biomass produced in the sunlit, upper ocean is controlled by the availability of Addition of limiting nutrient(s) to an ecosystem the scarcest nutrient. In low nutrient regions can have a fertilizing effect. If limitation is by a – shown above in light purple – N or P is the micronutrient, such as iron, much less needs limiting macro-nutrient. Such areas are ef- to be added to stimulate plant growth. fectively biological deserts, since their surface waters receive very low (re-)supply of N and P, In some low nutrient regions, limitation by N mostly by slow mixing with deeper, nutrient- can be overcome by specialised microorgan- rich water. In other regions, macro-nutrient