Das Projekt "Der globale Kohlenstoffzyklus und seine Stoerung durch den Menschen und das Klima II - Teil A: Atmosphaere" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Meteorologie durchgeführt. An observational program is conducted to record at several key locations the concentration of atmospheric CO2 and its 13C/12C and 14C/C isotope ratios, which provide constraints on the current distribution of surface sources and sinks of CO2. An atmospheric transport model is developed and applied in order to relate the observations from the global station monitoring network to the large scale distribution of surface sources and sinks. Variations of the past atmospheric CO2 concentration and its 13C/12C ratio are determined from analyses on air-bubbles in polar ice cores.These provide a means to assess the natural variability of the carbon cycle during the Holocene and the industrial period. A series of modelling studies of the past 30 years of direct atmospheric observations is conducted, using coupled three-dimensional carbon models of the atmosphere, ocean and terrestrial biosphere driven by observed climate. These studies allow to quantify the regional distribution of sources and sinks of CO2 and provide an assessment of carbon cycle feedbacks induced by climate fluctuations, in particular during El Nino/Southern Oscillation events. Using coupled carbon models of the atmosphere, ocean and terrestrial biosphere, simulations of the atmospheric CO2 concentration evolution are performed given prescribed scenarios of future industrial emissions and land use statistics.
Das Projekt "Europaeische Studie zu Kohlenstoff im Ozean, in der Biosphaere und Atmosphaere: Atm-Abteilung" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Meteorologie durchgeführt. A monitoring programme of the atmospheric concentration of CO2 and tis stable (13C/12C and 18O/16O in CO2) and radioactive (14C/C) isotope ratios is conducted, which is focussed on the North Atlantic, the European continent and on the Tropical Indian Ocean, which represent critical gaps in the currently operating global monitoring networks. These measurements are supplemented by observations of SF6, in order to provide a diagnostic tool to validate the atmospheric transport models used in the project. Furthermore, a new capability of measuring the oxygen to nitrogen ratio of atmospheric air using high-precision mass spectrometry is developed, which, in conjunction with atmospheric CO2 concentration observations, will permit a direct quantification of the relative contributions of terrestrial biospheric and oceanic CO2 source processes on regional and global scales. A series of model simulation studies will be conducted, comprising inversion studies with atmospheric transport models in order to establish constraints on magnitude and location of surface sources and sinks of atmospheric CO2 from atmospheric observations. Simulations of surface fluxes generated by prognostic, high-resolution models of the terrestrial and oceanic carbon reservoirs will be validated. Finally a series of scenario calculations of the future atmospheric CO2 concentration will be carried out based on scenarios of future energy and landuse using coupled comprehensive models of the global carbon cycle as developed and validated within ESCOBA.
Das Projekt "Modellierung des Kohlenstoffaustausches zwischen Waeldern, Holzprodukten und der Atmosphaere - Teil: ESCOBA - European Study of Carbon in Ocean, Atmosphere and Biosphere: Biosphere" wird vom Umweltbundesamt gefördert und von Joanneum Research Forschungsgesellschaft, Institut für Energieforschung durchgeführt. The influence of the management of the forest ecosystems as well as the utilization of wood on the global carbon cycle is expected to be large. The aim of this study is to simulate both the carbon exchange processes in managed forests and the effects of wood products and biofuel use on the carbon balance by coupling the Frankfurt Biosphere Model (FBM) with a wood utilization model. The coupled model is used to analyze four selected European countries: Austria, Finland, Germany and Portugal. Forest growth is simulated by the FBM, a global, mechanistic and prognostic biosphere model dependent on spatially and temporally varying climatic conditions. Management and harvest regimes are treated as an anthropogenic disturbance to the natural ecosystem, which leads to a forest called 'age class structured highforest'. The soil carbon model of the FBM allows the calculation of the net carbon exchange between the forest ecosystem (organisms in forests and soils) and the atmosphere. The use of age class distributions and four major tree species (pine, spruce, oak and beech) allows for an appropriate simulation of the carbon balance of the forests and the accompanying harvested biomass. Together with a matrix type model of age class dynamics, the full carbon balance of forestry can be simulated over a long period. Data on harvested wood are used by the wood utilization model to calculate the total carbon balance of the forest sector by different accounting approaches: the present 'Default IPCC Approach', the 'Stock-change Approach', the 'Production Approach' and the 'Atmospheric-flow Approach'. The amounts of industrial roundwood, wood products and fuelwood production including imports and exports are treated separately. CO2 releases from wood harvested in the past and carbon emission benefits from using wood for energy or products replacing other materials are considered as well. The approaches also require the calculation of the net ecosystem production (NEP) of a country's forest, provided by the FBM. Different scenarios approximating possible deviations from the 'business as usual' path regarding forest management and wood utilization are described.