Global Technical function: Managing
Technical Function Unit: Identifying, Modelling
Geographic Area: Germany

GHG EUROPE

Understanding the carbon cycle is a key issue for better estimating the effect of human activity on climate change. Several projects for improving the accuracy of existing models have been carried out in the last decade. Concerning the European terrestrial
greenhouse gas balance, existing assessments have only focused on one emission gas (carbon dioxide CO2, nitrous oxide N2O or methane CH4) and have been applied to only one land use.

More recent efforts have paid attention to reducing the uncertainty of the carbon balance. For example, the CARBOEUROPE-IP project has achieved a significant reduction (65%) of uncertainty in the carbon budget of European terrestrial ecosystems. Main troubles for having an accurate carbon balance still come from its high temporal and spatial variability, given the European continent has very different ecosystems, climates and land uses.

The GHG-EUROPE project aims to improve the diagnosis and prediction of Europe’s terrestrial CO2, NO2 and CH4 budget. The project lasts from 2010 to 2013, and is carried out by a consortium of 41 research entities from 15 countries, under the coordination of the Thuenen-Institute of Agricultural Climate Research (Germany). It is funded by the European Commission under the Seventh Framework Programme (FP7 ENV).

This project is structured around four overarching objectives. First, it focuses on analysing temporal changes of CO2, N2O and CH4 budgets of terrestrial ecosystems in Europe, trying to link year-on-year flux variations to natural and anthropogenic drivers. To achieve this, data mining techniques and recent advances in ecosystem modelling are exhaustively applied to data sets at several scales (from 0.25 x 0.25 º to 4 x 5 º, and from weeks to years) in order to establish the scale dependence of these drivers. Preliminary analysis of atmospheric inversions and Terrestrial Ecosystem Models (TEM) has shown large differences in trends across Europe: homogenous data with negative fluxes are found in the North, but contrary signs of fluxes can be found in the South depending of the applied approach.

The second objective of the project attempts to better understand the effects of natural and anthropogenic drivers on GHG fluxes. Along the project a deep review of GHG fluxes in peatlands is carried out, and the effect of land use changes for bioenergy, the effects of N deposition on the soil carbon cycle, and the impact of post-fire and litter quality impacts on carbon in Mediterranean shrublands is studied. Moreover, a comprehensive meta-analysis on land use change effects on soil carbon has been carried out, confirming that carbon losses are huge when forests are converted into croplands, but carbon accumulation on soils is low when croplands are reforested or converted into grasslands. Together with these works, additional GHG flux measurements have been initiated in some regions of Europe where only few data are available so far (e.g. Mediterranean shrublands, Romanian mixed beech forests)

A third field of work has focused on identifying the GHG processes that could be most vulnerable to changes in their drivers. The established methodology covers different phases:  1) the identification of response functions to different drivers. 2)  the parameterisation of models against available data, and validation against the obtained response functions. Depending on these responses, the models are improved accordingly. At the moment, seven sectorial models for croplands, forests and grasslands are evaluated, revealing correct correspondences for annual GHG budgets but high limitations for describing “hot moments” with high fluxes. Additionally, a deep study about how managing forests and croplands affects GHG fluxes has been carried out. Results showed influences of climate, soil and fertilisers on N2O emissions, which varied strongly depending on soil properties and climate.

Fourth project objective, which is still under development, is assessing the impact of future strategies and policies on carbon pools and GHG fluxes. Until now, main efforts focus on integrating and adapting existing models.

This project is still running, so a level 3 can be assigned in the TRL scale. Nevertheless, the results are expected to improve the predictive capacity of ecosystem models, and to provide a good basis for differentiating natural variations from those due to land management. In the near future, the project will provide effective tools for assessing the consequences of political choices on climate change.