"Greenhouse gases (GHG) inventories contain ineluctable uncertainties, which cause serious difficulties: (1) The compliance with commitments to reduce GHG emissions is not solved, although for most countries the emission changes agreed on under the Kyoto Protocol are often smaller than the uncertainty in their estimated emissions. (2) Neither of the emission trading systems deals with the uncertainty of emissions estimates. Thus, decreasing inventory uncertainty is of paramount importance to its credibility, quality of compliance, and proper functioning of trading systems. The project aims in improving accuracy of the inventories in countries with differentiated regions and/or high coverage by forests, where the standard inventory procedures fail in producing high accuracy inventories. The proposed solution is to use spatially distributed inventories and more detailed forest modeling. This kind of inventory has been already compiled in Lviv Polytechnic for West Ukraine. It uses multilevel mathematical models, digital maps, georeferenced databases, and appropriate software. The objective is to develop similar spatial inventory of GHG emissions for Poland. To achieve the required spatial resolution, our method relies on statistical scaling models. Systems Research Institute contributes here with the expertise in statistical modelling. These methodologies will be novel in preparing GHG inventories. Further reduction of uncertainty is expected by modification and adaptation of the methodology for Ukrainian conditions, accounting schemes and models of verified full carbon account of forest ecosystems (FCA) developed by IIASA. Information background will be represented by a hybrid land cover as system integration of all available sources of information in GIS environment; with spatial resolution 1 km. Uncertainties of the FCA are considered in details. This methodology is expected to be applied in Poland as a next step of cooperation."