Carboeurope

What is the role of the European continent in the global carbon cycle?

More precisely, what is Europe's carbon balance? How much CO₂ does it emit, and how much does it absorb? How can we reduce the uncertainties in our estimates of this balance at a local, regional and continental level? What mechanisms control the CO₂ exchanges in the biosphere, and how are they affected by changes in land use, management and climate? Are European efforts to reduce CO₂ emissions detectable in the atmosphere?

Since January 2004, CarboEurope has mobilised hundreds of European researchers on these questions, crucial from the scientific and the political point of view. Flux towers, flying laboratories, intensive observation campaigns, a new generation of computer models: with a budget of more than €30 million (of which €16 million are provided by the EU) and 90 institutions from 17 participating countries for a duration of five years, CarboEurope is presently the world's largest scientific initiative to address the carbon cycle.

Objectives of CarboEurope

1. Quantifying the carbon exchanges of the European continent.

How does carbon travel within the vast number of natural and human systems present on the European continent? What is Europe's carbon balance? How is it distributed over space and how does it evolve over time? Where are the carbon stocks and how do they vary?

Europe is far from being a homogeneous surface. Populations are distributed very irregularly, and there are many climatic and geographic sub-regions. With regard to CO₂ fluxes, it is a real mosaic of sources and sinks varying continuously with season, meteorological conditions, land use, management etc. We will determine the sources and sinks of this mosaic and their evolution in time, from the local to the continental scale, with unprecedented accuracy and precision.

2. Towards a better understanding of what explains these changes, on all possible levels

What mechanisms control the carbon cycle in European ecosystems, and thus determine our mosaic of carbon fluxes? How do human disturbances, in particular climatic and land use changes, influence these mechanisms and therefore the European carbon balance? For example, can increases in growth rate in certain forests (up to 40% or more in 50-year-old forests) be observed due to the increase in atmospheric CO₂?

CarboEurope will provide new answers to these questions for each large system compartment: vegetation (forests, meadows, wetlands, cultivated fields), soils, atmosphere etc. on three levels: local, regional and continental. We will seek in particular to understand:

• the distribution of CO₂ fluxes between the three fundamental causes of exchange: 'breathing' of the biosphere by decomposition of organic material, harvest and fires; assimilation by plants; and combustion of fossil fuels

• the way in which this distribution evolves in time and space, and according to human activities.

Understanding goes beyond a mere description: it means discovering the ecological relationships and the mathematical laws behind all these mechanisms.

3. Providing the EU with the scientific instruments required for the verification of commitments taken on within the Kyoto Protocol

In order to fulfil its commitments for emissions reductions, the EU can take measures to reduce the emissions at source (by means of policies favouring public transport, clean industries, renewable energies, etc.) and to increase the natural sequestration of carbon (in particular with the management of existing forests and with new plantations). Will we be able then to measure the reduction in atmospheric CO₂ that is expected as a result of our efforts? How can we check that the objective, to reduce emissions, has truly been met and that the method used to meet it is truly effective?

CarboEurope will provide the EU with an observation system to detect changes in carbon stocks and fluxes. Moreover, in anticipation of the negotiations for the following commitment period envisaged by the protocol (2013 to 2018), we will lay the foundations for an accurate accounting system for carbon stocks and fluxes to be applied to all countries of the European Union.

What does it rely on?

CarboEurope is continuing work on a cluster of European projects on various aspects of the carbon cycle that have been running since 1996. These projects have assured the development of the major measurement networks on which research relies today, and in particular of the flux tower methodology. These flux towers can be seen as the skeleton of CarboEurope: they constantly, 24 hours a day, measure carbon fluxes, that is, the quantity of CO₂ absorbed or released by a specific measured area, as a function of time of day, weather conditions, season, etc.

That is how we were recently able to uncover a fundamental piece of data: the forests and prairies of the EU naturally absorb significant quantities of carbon, between 7 and 11% of European emissions of CO₂ from fossil fuels. But this key information leads us back to the major unknown factors: what happens to the carbon absorbed by these natural European sinks? Is it stored durably or temporarily? How vulnerable are natural sinks to climate change?