National top-down, bottom-up reconciliation

Objectives and ambitions

Despite the rapid growth of GHG measurement programmes across the world, there remain only a handful of countries who routinely include top-down evaluation methods in their inventory reports to the UNFCCC. There are both scientific and practical reasons for this: a) top-down methods are primarily able to quantify total or net fluxes, making it difficult for inventory teams to discern which sectors may be responsible for any mismatch with reported estimates, b) scientists often have little practical experience navigating the complex inventory process, making it difficult to gain impact from their research. In PARIS we will reduce barriers between inventory teams and GHG researchers in our focus countries by evaluating inventory estimates for ‘easy win’ compounds (for example, F-gases), developing sector-level emissions estimates for gases with complex sources, and exchanging knowledge between countries with evaluation programmes in different stages of development. The latter will be enacted through the delivery of draft annexes to National Inventory Reports to inventory teams.


PARIS will synthesise fluxes that are estimated by using improved top-down and bottom-up methods. Measurement data will be combined into information that is directly comparable and meaningful to inventory compilers. Furthermore, PARIS will provide country-specific GHG and BC/OM verification reports. Results are integrated through a template created for an Annex to the National Inventory Reports in a format that allows direct comparison of the reported inventories. This template will be provided to all national leads and will be used to efficiently compile top-down emission estimates for each focus country. PARIS engages constructively with inventory compilers in the eight focus countries: Germany, Netherlands, Hungary, UK, Switzerland, Italy, Norway, Ireland. This is to ensure that the outcomes of this project are of relevance to those communities.


Initial engagement with national inventory compilers – At the outset of the project, we will meet with our national inventory contacts (based on our existing relationships with these teams) from each focus country and the EEA to establish the framework of engagement in PARIS.

Create a template for an Annex to the National Inventory Report – A template will be created for an Annex to the National Inventory Report that allows direct comparison to different aspects of the reported inventories, including down to sector-level where feasible.

Synthesise measurement results – The template created will be used to combine the measurement outputs and produce country-specific GHG and BC/OM verification reports.

Annual engagement with inventory teams – We will present the Annexes with the country-specific results to the focus country inventory compilers and the EEA, with the aim to gain their insights and perspectives and give feedback back to the consortium to maximise the impact of the subsequent reports. This will be an iterative process repeated regularly in the project years 2 to 4.