The CarboEurope Cluster of FP5 was globally the first successful effort in action in which a coherent, comprehensive integration of terrestrial and atmospheric carbon sciences has been realized at continental scale. The cluster is now regarded as a “template” for world research on the Carbon Cycle. The USA , Japan and China are all launching similar initiatives. The CarboEurope Cluster has established the world´s leading, best integrated observing capacity built on flux networks, systematic ecological sampling and atmospheric long term observations collected in a co-ordinated manner, with in some cases real time data transmission and real time archiving on databases. The CarboEurope Cluster nested measurement strategy contains atmospheric and terrestrial observations from local, through regional and continental scale. It served as template for new initiatives and was adopted in the GTOS-TCO report. It will provide an important contribution to GTOS-TCO and IGCO through the lifetime of CarboEurope-IP.
The ecosystem observing network builds upon the scientific heritage of former European and nationally supported projects since the mid 1990s (FP3 and 4). More recently, as part of FP5, within projects Carboeuroflux, Carbo-Age, Greengrass and Forcast, we have set up a coordinated European ecosystem observing system capable to monitor CO 2, energy and water vapour exchange at 30 sites across Europe by harmonized eddy covariance measurements, and associated measurements of soil respiration and other important ecosystem carbon fluxes. There was a clear focus on forests, including seven chronosequences. More recently the observations expanded to grasslands, whilst croplands, wetlands and Central and Eastern European ecosystems were under-represented.
The FP5 project Recab was conceived as a feasibility study of a generic, coupled biosphere atmosphere modelling and experimental approach to quantify fossil fuel emissions and biospheric sources and sinks at the regional scale. The experimental work consisted of observational winter and summer campaigns in 5 contrasting climatic areas in Europe to assess regional exchanges between land surface and atmosphere. Europe achieved through Recab the capability of making high quality flux measurements at the 2 to 4 km scale from low flying aircraft and providing estimates at 20 to 50 km scale by convective boundary layer (CBL) budgeting. Several groups are now building on this expertise and are proposing to acquire a similar capability. The campaigns of typically 1 to 2 weeks have fully proven the feasibility of the approach, but were not aimed to produce a seasonal or annual regional carbon budget.
The atmospheric observing network also builds upon the scientific heritage of former European and nationally supported projects over at least a decade. More recently, as part of FP5, within projects Aerocarb, Chiotto and Tacos, we have set up a coordinated European atmospheric observing system capable to monitor the carbon balance of the whole continent, and attribute it to the underlying processes: fossil fuel emissions and ecosystem carbon sequestration or losses. This observing system is composed of a network of ground level in-situ CO 2 monitoring stations, a network of tall tower-based in-situ CO 2, CH 4, N 2O monitoring stations, a network of aircraft vertical profiles at bi-weekly frequency and flask sampling of tracers which attribute carbon fluxes to processes of biospheric and anthopogenic nature. The data are delivered to atmospheric meso-scale and global tracer transport models, which run in an inverse mode and determine CO 2 sources and sinks at large scale.
Despite these achievements, further harmonisation and integration of these parallel efforts in space and time is needed. Also a better compilation and direction of auxilliary data sets and tools towards the needs of modelers must be obtained. Carbodata developed a database of eddy flux measurements and ecosystem parameters from the former projects Euroflux, Medeflu and Canif. The databases of recent data in FP5 projects were established within the individual projects, but these were not harmonized with respect to format and content. Ecosystem models for scaling up from local ecosystems to larger regions (bottom-up modelling) were developed and improved in the FP5 project Carbodata. Top-down and inverse modelling was performed at regional (Recab) and continental scale (Aerocarb) using meso scale atmospheric models and global atmospheric models with a zoom over Europe . Novel methodologies for forest carbon inventories are developed in the FP5 project Carbo-Invent over test areas of Europe . Also, the Concerted Action CarboEurope-GHG aims at collecting and synthesizing all relevant scientific information about the European greenhouse gas budget from existing data, including human emissions, sources and sinks in freshwater and coastal zones, and Non-CO 2 gases. In addition, the recently started project Camels will pioneer a highly innovative method of estimating contemporary carbon fluxes, involving the assimilation of observed data into terrestrial Carbon Cycle models. Despite all this, further improvement of the accuracy of the data and estimates and better constraints of the models are needed.
The key innovation and enhancement of this state of the art in the CarboEurope-IP is in its conception as to apply single comprehensive experimental strategy. All experimental and modelling and integration Components are planned from the start in an integrative complementary manner. Similar techniques are being used at local, regional and continental scales to measure and model CO 2 fluxes and atmospheric CO 2 concentrations, which are amended by specific scale-dependent complementary approaches. They are tuned to achieve the accuracy required for model predictions. There is consensus with respect to the experimental design that it shall facilitate the integration of the various scale dependent components.
The CarboEurope-IP will attempt to track the impact of the biosphere on atmospheric CO 2 and thus help verifying European reduction measures as committed in the framework of the Kyoto Protocol. We will deliver a prototype monitoring and data assimilation system, which is unique in the world in its comprehensiveness, and in its level of integration and breadth. This will for the first time provide quantitative information to support the implementation of the Kyoto protocol in Europe . Furthermore it will, for the first time, provide the quantitative information for full carbon accounting at local, regional and continental scales. Although this is not yet part of the present arrangement of the Kyoto Protocol, we believe that the CarboEurope results may enter the discussions about Full Carbon Accounting that are currently held for Kyoto II.
The bottom-up and top-down approaches will individually not be able to reduce the uncertainties in the estimates of the European carbon balance below 20 to 30%. However, using the multiple constraint approach, we are confident to reduce the uncertainty to a level of 10 to 20% or better.
We will also provide the quantitative information for vulnerability of carbon pools at a 100 yr timescale and provide the quantitative information of carbon pool changes at 20 yr time scale. This will allow evaluation of the vulnerability of the Carbon Cycle at key timescales of management and detect surprises in the climate system at shorter and longer timescales where gradual and transient global change effects may affect the vulnerability of the carbon pools.
updated by Yvonne Hofmann,