CMP5 – Delivering global and regional carbon budgets annually, including their uncertainty

This Component synthesizes a wide range of different products to enhance their individual information content. It produces a high-level synthesis of existing information on an annual basis for large regions of the world, thus contributing to and expanding the efforts of the annual budget activities that have been led by the GCP since 2005, and which have informed policymakers around the world (Raupach et al. 2007; Friedlingstein et al. 2010) .

The specific objectives of this Component are:

  • development and implementation of a strategy to estimate the annual CO2 budgets for the globe and for key regions
  • development of a protocol to estimate their uncertainty and confidence level
  • delivery of such budgets and their uncertainty.

The global and regional budgets will be based on the synthesis of data-based estimates (CMPs 1 and 4), data assimilation systems (CMP 2), and process models. This effort will need to ensure that the data and model results can be used either directly (resulting from CMP2), or indirectly to provide either regional information, to evaluate model results, or to provide information on variability and uncertainty. The strategy will need to be adapted for each world region because the amount and quality of the data greatly varies around the world. In some regions, model results only may be available. The merging of products is an emerging issue in climate science (Knutti et al. 2010), which needs to be explored also when attempting to merge information on the carbon cycle. The assessment of uncertainty in global and regional budgets is equally complex. It will require a consideration of the uncertainty in the data and their extrapolation where available, an estimate of model range, and estimate of the performance of models (including assimilation systems). Furthermore, a confidence level can be provided based on the guidelines of the IPCC, by considering the type, amount, quality and consistency of the available evidence, and their level of agreement. We will provide traceable accounts on our assessment for external scrutiny.

The global and regional CO2 budget publications will continue to provide information on integrated carbon information that is relevant to policy makers, the public, and other scientists. Furthermore, this effort in cooperation with the GEO Carbon Office of CMP8 will provide a strong foundation for the development of an International Carbon Office in the future (Le Quéré et al. 2010), which could provide the integrated assessments of the physical carbon cycle fostered by GEOCARBON.