Problems to be solved
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 objective 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 replicating 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 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. Next climate change scenario' notably changes in Fe inputs, will be run, with special attention to climatic feedback (warming) on the oceanic cycles and fluxes.
Under the Kyoto Protocol, the European states have committed them selves to the quantification and prediction of future trends in the concentration of greenhouse gases in the atmosphere. This project will reduce the uncertainties in the modelled sources and sinks of carbon in the ocean. The new OBCM' s will be able to predict more realistic climate scenario' s, notably climatic feedback on oceanic biogeochemistry.
Funding SchemeCSC - Cost-sharing contracts
91198 Gif Sur Yvette
91191 Gif Sur Yvette
L69 3BX Liverpool
9751 NN Haren Gn
PL4 8AA Plymouth