Present and future greenhouse gas (GHG) balances of terrestrial ecosystems are at the core of scientific and political issues, as increases in terrestrial CO2 and CH4 emissions will accelerate Global Warming. A new large scale European infrastructure is d evoted to this issue: the International Carbon Observation System (ICOS, ESFRI-Preparatory Phase) which aims at a continuous estimation of CO2, CH4 (and N2O) fluxes over a 10 by 10 km grid in Europe. This effort is relevant to national GHG monitoring (SFT , CICERO), international commissions (AMAP, ACIA, Nordic Council) and international monitoring programs (GEMS, GEOSS). ICOS will be the instrument of choice to verify efficiencies of mitigations measures in terrestrial ecosystems and fossil fuel usage (as it will apportion anthropogenic vs. natural GHG sources). ICOS should become a central instrument to the ambitious climate policy that Norway has recently adopted. To achieve its ambitious goal, ICOS relies on three components: 1) a network of ecosystem GHG-flux sites, 2) a network of atmospheric GHG-concentration sites, 3) a network of ocean GHG monitoring systems. The general objective of this proposal is to plan the needed development in scientific capacity, monitoring and research infrastructure, and legal consortium structures (national and EU), in order to prepare Norway for joining the Integrated Carbon Observation System (ICOS) in 2011. This general objective needs to be met for terrestrial, atmospheric and oceanic components for ICOS