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IRONAGES - Iron Resources and Oceanic Nutrients - Advancement of Global Environment Simulations

Summary information

Funding:FP5 - Research project
Total cost:2324197
Ec contribution:1582774
Start date:2000-03-31
End date:2003-09-30
Duration:42 months
Coordinator:Hein de Baar (
Organisation:Royal Netherlands Institute for Sea Research - Netherlands
Keywords:Ocean ecosystems; global carbon cycle; climate system; Ocean Biogeochemical Climate Models (OBCM's)
Project name:IRONAGES - Iron Resources and Oceanic Nutrients - Advancement of Global Environment Simulations
Project summary:Abstract
The functioning of ocean ecosystems and their interaction with the global carbon cycle and the climate system is not very well known. Ocean Biogeochemical Climate Models (OBCM's) are still too simplistic to adequately describe observed changes in ocean biology and chemistry in space and time. Therefore large uncertainties remain concerning the carbon up-take by the ocean that also limits the predictability of the future carbon up-take.

Scientific objectives and approach
The work outlined seeks to better model marine ecosystems and the sources and sinks of C, N and other elements within those systems, assuming that a number of factors (notably light, N, P, Si, Fe) are co-limiting plankton blooms. This goal will be achieved through a combination of laboratory experiments, fieldwork and modelling. Laboratory work will target the predominant algal species of the major taxonomic groups and determine their growth as a function of multiple stresses, such as limitations of iron, light and macronutrients. This data will then be used to refine and improve ocean ecosystem models, with the aim to more accurately replicate observations of the natural system. New realistic OBCM' s will be developed for budgeting and exchanges of both CO2 and DMS, implementing: (I) co-limitation by 4 nutrients of 5 major taxonomic classes of phyto-plankton, (II) DMS (P) pathways, (III) global iron cycling, (IV) chemical forms of iron and (V) iron supply into surface waters. Input from below of iron from anoxic sediments of coastal margins will be assessed along a 2-D vertical section from Europe into the centre of the north Atlantic. Input from above of Fe (II) dissolved in rainwater from Sahara dust blown over the central Atlantic will be quantified at sea, and related to observed plankton production, CO2 gas exchange and dimethylsulfide (DMS) emission. Different chemical forms of iron will be analysed and rigorous certification of all Fe in seawater data will be ensured. For 2 major DMS-producing algal groups the life cycle, Fe limitation, export production, CO2 uptake and DMS emissions will be synthesised from existing literature and laboratory experiments. Experimental data will be fed into an ecosystem model. Also DMS (P) pathway modelling will be carried out being expanded with 3 other groups of algal and DMS (P) pathways. The extended ecosystem model will provide reliable output for CO2/DMS gas exchange being implemented into two existing OBCM's. Then climate change scenarios notably changes in Fe inputs, will be run, with special attention to climatic feedback (warming) on the oceanic cycles.
Project outputs:Scientific achievements
Iron input into the oceans, iron originating from reduced Fe(II) from anoxic sediments of coastal margins (iron from below), as well as from aeolian input from above of Fe(II) dissolved in rainwater from Sahara-derived dust blown over the central Atlantic (iron from above) was quantified. These fluxes were related to observed phytoplankton production, CO2 gas exchange and DMS emission. Moreover, the different chemical species of Fe were determined. Finally, these field data were used to construct a simple global Fe cycling model. The physiology, life cycle, Fe limitation, export production, CO2 uptake and DMS emissions for the two major DMS producing colony-forming Phaeocystis spp. and calcifying Emiliania huxleyi as well as three other major classes of marine phytoplankton (diatoms, N2 fixing diazotrophs and the small picoand nanoplankton) were synthesised from existing literature in combination with additional laboratory experiments. The ensuing know-how was fed into below ecosystem modelling, as well as into the DMS(P) pathway modelling. The existing phytoplankton ecosystem model (SW AMCO) was expanded with the 3 other taxonomic groups and also the DMS(P) pathways simulation. Expansion of the global iron model as well as the SW AMCO model were used for improvement of the Ocean Biogeochemical Climate Model (OBCM's), with as ultimate aim of IRONAGES to run climate change scenario's, notably changes in Fe inputs, with special attention to climatic feedbacks (warming) on the oceanic cycles and fluxes.

Field data on iron fluxes from sediments as well as from atmospheric input, collected during several cruises, were made available. A Fe certification exercise ensured reliable measurements of ultra-low iron concentrations. A global Fe cycling model was constructed. Reviews of five major taxonomic groups of marine phytoplankton were made available. Additional laboratory experiments filled gaps in physiological knowledge on these groups. An ecosystem model SWAMCO, was expanded using the scientific knowledge on the 5 taxonomical groups. The simple Fe cycling model, as well as the SWAMCO model, were used to improve Ocean Biogeochemical Climate Modelling.

An IRONAGES data product CD is available upon request from the coordinator institute (see website).

Socio-economic relevance and policy implications
The results from IRONAGES helps to address the issues of quality of life and health and safety by constructing tools with which, future climate forecasts will have a greater degree of certainty than is currently available. The results of this work directly enable EU policymakers and planners to propose new policies that deal with the impacts of climate change with the highest possible confidence. The development of the marine ecosystem models creates a tool to test the sustainability of such systems under conditions of climate change or anthropogenic perturbation. This allows then for ecosystem conservation and management resource policies to be developed with reduced uncertainty about the possible changes in climate and the ramifications arising from that. Any policy decision on reduced CO2 emissions will implicitly affect the longer-term availability of natural resources: petroleum, natural gas and coal.

The improved OBCMs developed within IRONAGES enable studying the influence of potential climate change on the biogeochemistry in the oceans and possible feedbacks to climate. Changes in mixed layer depth and temperature driven by climate change will influence the composition of phytoplankton, leading to changes in the biogeochemical cycling of a number of compounds, such as DMS that influence climate. Changes in DMS production have the potential to offset climate changes due to increasing CO2 levels, especially singe anthropogenic sulphur emissions to the atmosphere have been reduced strongly in recent time.