Second and final report on research needs for verification

The VERIFY project has identified and documented many ways to reduce the uncertainty of GHG flux estimates through the provision of new datasets and modelling methods. To achieve reliable verification of climate policy in a useful timeframe, additional work is required and VERIFY scientists have outlined some of the necessary approaches through reports, published literature and in responses to the survey conducted in this deliverable. While several steps have begun to be implemented, others could be in the near future. Some of the required steps are specific to an individual work package while others apply throughout. The body of this report summarises these approaches. Attention is often focussed upon methodological differences, including variation in input data, as well as the implementation of three main approaches: bottom-up (BU) process-based models; top-down (TD) inversions; and national greenhouse gas inventories (NGHGI). A clear finding of the report is that each of the approaches serve an important role and therefore uncertainty can be minimised by planning how best to combine each approach to achieve an optimal estimate. However, continued enhancement of communication and collaboration between scientific research communities and the inventory community will help to reduce uncertainty. In addition, there is a clear need for collection of better-quality data at higher spatial and temporal resolution (both in-situ and remotely sensed) and in areas that are not currently well covered. Tackling those gases and sectors with the highest uncertainty that can impact emissions at the national scale, should have the largest impact on reducing current uncertainty levels.