Today, countries use a wide variety of methods to monitor the carbon cycle and it is difficult to compare datafromcountry to country and to get a clear global picture. The current global observational and modelling capabilitiesallow us to produce estimates of carbon budget at different level (from local to global) but many uncertainties stillremain. Decision makers need now more than ever systematic, consistent and transparent data, information andtools for an independent and reliable verification process of greenhouse gas emissions and sinks. Thereforehigher quality and quantity of CO2 and CH4 data, from different domains and with an enhanced spatial andtemporal resolution, need to be collected by a globally integrated observation and analysis system. This can beobtained by the coordinated Global Carbon Observation and Analysis System that this project aims at designing,addressing the climate targets of the Group on Earth Observations (GEO) toward building a Global EarthObservation System of Systems (GEOSS) for carbon.Specific objectives of the GEOCARBON project are:• Provide an aggregated set of harmonized global carbon data information (integrating the land, ocean,atmosphere and human dimension)• Develop improved Carbon Cycle Data Assimilation Systems (CCDAS)• Define the specifications for an operational Global Carbon Observing System• Provide improved regional carbon budgets of Amazon and Central Africa• Provide comprehensive and synthetic information on the annual sources and sinks of CO2 for the globeand for large ocean and land regions• Improve the assessment of global CH4 sources and sinks and develop the CH4 observing systemcomponent• Provide an economic assessment of the value of an enhanced Global Carbon Observing System• Strengthen the effectiveness of the European (and global) Carbon Community participation in the GEOsystem