Inventory of EU Marine Climate Change Research

New search

CARBOOCEAN - Marine Carbon Sources and Sinks Assessment

Summary information

Funding:FP6 - Integrated Project
Total cost:19230000
Ec contribution:14500000
Start date:2005-01-01
End date:2009-12-31
Duration:60 months
Coordinator:Christoph Heinze (
Organisation:University of Bergen and Bjerknes Centre for Climate Research – Norway
Themes:Ocean acidification
Regio:North Atlantic, Southern Ocean, European Regional Seas, World Ocean
Keywords:Carbon cycle; CO2 uptake; Kyoto Protocol; marine biogeochemistry; Climate; Atlantic Ocean; Southern Ocean; World Oceans; US partners; Earth Sciences; Numerical ocean modelling; Marine carbon and oxygen observations; Marine carbon data syntheses
Project name:CARBOOCEAN - Marine Carbon Sources and Sinks Assessment
Project summary:CARBOOCEAN IP (= CarboOcean Integrated Project) aimed at an accurate scientific assessment of the marine carbon sources and sinks within space and time. It focused on the Atlantic and Southern Oceans and a time interval of -200 to +200 years from now.
CARBOOCEAN was successful in determining the ocean’s quantitative role for uptake of atmospheric carbon dioxide (CO2), the most important manageable driving agent for climate change.
CARBOOCEAN thus created new scientific knowledge as an essential foundation for a quantitative risk/uncertainty judgement on the expected consequences of rising atmospheric CO2 concentrations. Based on this judgement, it will be possible to guide the development of appropriate mitigation actions, such as management of CO2 emission reductions within a global context.
CARBOOCEAN combined the key European experts and scientific resources in the field through an integrated research effort. The effort complemented other major research programmes on oceanic, atmospheric, and terrestrial carbon cycling and was linked to these programmes.

The ultimate goal of Integrated Project CARBOOCEAN was to reduce the present uncertainties in the quantification of net annual air-sea CO2 fluxes. Particular emphasis was placed on the Atlantic Ocean and the Southern Ocean as the main deep water production areas, but also the World Ocean as a whole is considered. The target was to reduce the uncertainties by a factor of 2 for the world ocean and by a factor of 4 for the Atlantic Ocean. The IP delivered a description, process oriented understanding and prediction of the marine carbon sources and sinks with special emphasis on the Atlantic and Southern Oceans on a time scale –200 to +200 years from now. Specific objectives were:

1. Description and quantification of the CO2 air-sea exchange on a seasonal-to-interannual scale for the Atlantic Ocean and the Southern Ocean
2. Quantification of decadal-to-centennial large-scale Atlantic and Southern Ocean carbon inventory changes
3. Quantification of the carbon sources and sinks at the European regional scale
4. Identification and understanding of biogeochemical feedback mechanisms which control marine carbon uptake and release
5. Integration of carbon observations into an integrated prognostic modelling framework
Project outputs:The CARBOOCEAN achievements represent the cutting edge in marine carbon cycle research in the domains of interest to the project. They are embedded in the international research community and have triggered new collborations and fostered existing collaborations. The record of peer reviewed publications form the CARBOOCEAN IP documents the high standard of the research results (including papers in Nature and Science). To illustrate this, we give below for each core theme, examples where CARBOOCEAN research has lead to new knowledge which will also have considerable effect beyond the project end and which are shaping our present research questions as well as new up-coming research directions.

1. At basin wide/regional scale the air-sea CO 2 fluxes are interannually more variable than previously thought (e.g. Schuster et al., 2009; Watson et al., 2009; Metzl, 2009; Le Quéré et al., 2007) especially in regions of vertical downward mixing of water close to saturation with respect to the atmospheric CO 2 concentration. This new knowledge will help to re-design coming ocean observatories for carbon (such as initiated through the the ESFRI programme in ICOS – Integrated Carbon Observing System). This new finding is also fundamental in our general understanding of ocean carbon cycling: The ocean sink is not as reliable and steady, at least at the regional level, as many analysis methods (assuming steady state conditions) expect. In some ways the finding of highly variable air-sea CO2 fluxes represent a paradigm shift in global carbon cycle research. The analysis of VOS line data for establishing basin-wide fluxes is currently also tested for the Pacific Ocean as CARBOOCEAN supported PhD student M. Telszewski started a post-doc position in Japan. The link between a temporarily decreasing Southern Ocean carbon sink and stratospheric ozone is a completely new aspect of Earth system science underlining the need for truly coupled multi-reservoir Earth system models. CARBOOCEAN researchers are also partners in the newest sea surface fugacity of CO2 climatology as produced under US lead authorship with many international contributors. The CARBOOCEAN work on the North Atlantic and Southern Ocean ideally complement the work by international colleagues on the Pacific Ocean and particularly the El Nino/Southern Oscillation associated changes in air-sea carbon exchange.

2. The most comprehensive highest accuracy consistent carbon cycle tracer data set for the Atlantic available to date is the CARINA data set, which consists of a large number of pre-CARBOOCEAN data, data sampled during CARBOOCEAN, and many data sets from international colleagues. CARBOOCEAN was instrumental in bringing this data set to life. The data set nicely complements the GLODAP data set compiled under guidance of R.M. Key (Key et al., 2004). Bob Key from Princeton University was also a central figure in the compilation of CARINA. An effort similar to CARINA has now also started in the circum-Pacific Asian-American communities under the name PICES and will lead, together with CARINA, to a world-wide extreme high quality carbon data set. This data set will also have to be updated in the future due to the transient nature of the marine carbon cycle. CARBOOCEAN also provided new estimates on Atlantic inventories of excess carbon due to the anthropogenic carbon perturbation. The high latitude oceans can well have a considerably higher amount of anthrpogenic carbon stored in their water column than previously estimated. Inverse computations of intra-ocean fluxes and air-sea carbon fluxes through international-US efforts were supported by contributions from CARBOOCEAN.

3. The contribution of European regional seas to the Atlantic and European carbon budget was significantly better quantified than through previous efforts. The seasonal analysis of an entire regional seas basin and the systematic seasonal reccoupation of the Strait of Gibraltar hydrographic cross section with marine carbon measurements, can be regarded as milestones towards a systematic quantification of the carbon fluxes along the land-ocean continuum. A series of new process and case studies has indicated new processes through re-mineralisation of shallow organic sediments and associated alkalinity release and new procdures for biogeochmemical pH computations. Borges and Gypens (2010) have shown that in the discussion about ocean acidification, eutrophication in the coastal seas has an even stronger impact on the carbonate system and hence must be taken into account in continental seas carbon cycling. CARBOOCEAN scientists have contributed to the new international text book (Liu et al., 2010) on carbon and nutrient fluxes in continental margins.

4. The dependence of nutrient utilisation by biota on increase in ambient CO2 partial pressure (and associated pH decrease and decrase in calcium carbonate saturation) as resulting from Riebesell et a. (2007) has triggered a new line of research on non-stoichiometric carbon cycle midelling, where the assumed “Redfield concept” of constant ratios of P:N:C:ΔO2 in most biogeochemical ocean models is abandoned. It is under discussion, whether the relationship as deduced from mesocosm experiments can be transferred to other situations and regions or not. If yes, it could include a potentially significant feedback to rising CO2. In any case a process on re-thinking older established concepts in marine biogeochemical understanding has now been started, and has, e.g., lead to a new interface between Earth system models and the marine paleoclimatic sedimentary record (Heinze et al., 2009) which can help to solve the issue in future by looking at past changes of the Earth system. Gehlen et al. (2008) could show how quickly the sea surface signal of ocean acidification is transferred to the deep ocean where high CO2 water is starting to dissolve marine calcium carbonate sediments. This study complements nicely earlier studies with coarser models on the long-term negative feedback induced by sediment dissolution carried out by US researcher Archer (2005). Further, a cutting edge summary and description on the term “alkalinity” was published (Wolf-Gladrow et al., 2007) which will enter the scientific literature as a classic paper on this often not unambiguously discussed carbon cycle tracer (see discussions in Rakestraw, 1949; Dickson, 1992).

5. A new isopycnic physical-biogeochemical carbon cycle model was developed based on the existing modules MICOM and HAMOCC (Assmann et al., 2010) and implemented into a new Earth system model (Tjiputra et al., 2010). Next to the isopycnic ocean model version used at GFDL Princeton (GOLD model), this is the only isopycnic ocean Earth system model currently available and hence very useful in intercomparisons such as the CMIP5 programme in view of the 5th IPCC Assessment Report of Working Group 1. Systematic predictive scenarios with 4 comprehensive Earth system models have provided hindcasts (since the onset of industrialisation) and future projections (under assumptions of an SRES A2 emission scenario) for global as well as regional air-sea carbon fluxes which will enter the RECCAP analysis of the Global Carbon Project (Roy et al., to be submitted) in the years to come.

The project achieved a dissemination to policy makers including members of the European Parliament, to schools and to the general public. The project was instrumental in initiating further research projects and coordinating activities (such as the European FP7 project on ocean acidification, EPOCA, and the EU FP7 coordination action, COCOS). The instrumental Integrated Project has worked extremely well for the European carbon cycle community and has contributed to the competitiveness of European research in this field. The international collaboration, in particular with he US through partner Princeton University, was indeed extremely fruitful. Towards the end of CARBOOCEAN, important review/progress overview papers were published together with US partners.

An extensive list with references of cited and other CARBOOCEAN related publications can be found on the project website.