The main concept of VERIFY is to provide observation-based estimates of anthropogenic and natural GHG emissions and sinks as well as associated uncertainties. The proposed approach is based on the integration of atmospheric measurements, improved emission inventories, ecosystem data, and satellite observations, and on an understanding of processes controlling GHG fluxes (ecosystem models, GHG emission models).

Two complementary approaches relying on observational data-streams will be combined in VERIFY to quantify GHG fluxes: 1) atmospheric GHG concentrations from satellites and ground-based networks (top-down atmospheric inversion models) and 2) bottom-up activity data (e.g. fuel use and emission factors) and ecosystem measurements bottom-up models). For CO2, a specific effort will be made to separate fossil fuel emissions from ecosystems fluxes.

Integration of top-down and bottom-up information in a pre-operational system: because it can combine bottom-up inventories with atmospheric measurements, the top-down approach represents the ultimate synthesis estimation combining all information available to deliver net GHG budget estimates. On the other hand, the bottom up approach offers the additional possibility to attribute GHG budgets to sectors and processes. VERIFY will bring together the best of each approach in a robust and transparent system designed during the project for future longterm operations (see Figure below).

H2020 proposal 2
Figure: Concept of the proposed pre-operational “science-based” system to monitor GHGs.

WP1 - Discrepancies in inventories

The main objective of WP1 is to assess and document the priority needs of official (national) inventory-preparing institutions to establish policy-relevant observation-based GHG budgets estimation methods that will be prototyped in WPs 2 to 4. This WP will provide the needed link and dialogue to address the policies and StockTake process from the Paris Agreement for the three GHGs with the common involvement of inventory agencies and research groups participating to the project. WP1 will connect to other WPs through: i) the assessment of the current UNFCCC MRV framework and its future evolution, e.g. to address the recommendations produced in 2019 by the IPCC Task Force on National GHG Inventories14 and ii) a careful and detailed analysis of uncertainties in National inventories with respect to the main needs and gaps per country, sector, gas, establishing regular interactions between the different communities. WP1 will contribute to the delivery of Product 4 with WP6.

The main objective of WP1 is to assess and document the priority needs of official (national) inventory-preparing institutions to establish policy-relevant observation-based GHG budgets estimation methods that will be prototyped in WPs 2 to 4. This WP will provide the needed link and dialogue to address the policies and StockTake process from the Paris Agreement for the three GHGs with the common involvement of inventory agencies and research groups participating to the project. WP1 will connect to other WPs through: i) the assessment of the current UNFCCC MRV framework and its future evolution, e.g. to address the recommendations produced in 2019 by the IPCC Task Force on National GHG Inventories14 and ii) a careful and detailed analysis of uncertainties in National inventories with respect to the main needs and gaps per country, sector, gas, establishing regular interactions between the different communities. WP1 will contribute to the delivery of Product 4 with WP6.

WP2 to WP4 - GHG monitoring and verification system component design

WP2, 3 and 4 will perform the research needed for a pre-operational policy-relevant GHG observation system. The three WPs cover the data collection and development of advanced algorithms for the estimation of fossil fuel combustion CO2 emissions (WP2), terrestrial CO2 sources and sinks and carbon stocks (WP3) and all types of CH4 and N2O emissions (WP4). This will provide Product 1 and Product 2. WP2, 3 and 4 follow the same follow a common structure that includes: i) the collection and processing of all needed input data with yearly updates, ii) the integration into pre-operational systems of bottom-up models currently developed for research applications (ecosystem models, very detailed emission mapping models) and atmospheric inversion models and iii) targeted research actions to further improve these model tools to use recent and upcoming space-borne observations and develop cutting-edge new model data fusion techniques. For the bottom-up component, selected models will be integrated under the same protocol to deliver annual GHG flux maps at 10 km, weekly across the EU (covering all land use types and emission sectors). For the top-down component, there will be two stages: in the first stage we will use existing inversion systems to provide GHG flux estimates at 50 km, weekly resolution during the first three years of the project, then, in the second stage, a unified Community Inversion Framework (CIF, see text-box) that will be built to integrate different transport models and inversions, paving the way for a future operational system.


Observation-based methods to quantify fossil fuel combustion CO2 emissions (WP2)
Improving and independently verifying fossil15 fuel CO2 (ffCO2) budgets on the national scale, for reporting to the UNFCCC, and for regional emission hot spots (e.g. large urban areas) have a high political priority. However, current CO2 observation systems are not well suited to quantify ffCO2 on either spatial scale.
To address this challenge, WP2 will develop a dynamic emission-mapping model that will ingest near-real-time activity data (e.g., energy demand, traffic intensities, socio-economic drivers) and proxies for predictive modelling of these activities (e.g. meteorology), and will further optimise the resulting emission estimates using various independent data streams. This model will provide high spatially (< 10 km) and temporally (hourly) resolved emissions of ffCO2 and of co-emitted species. The model output will be evaluated using isotopes and tracer measurements collected over the selected hotspot region of the Rhine valley (Germany). Several measurement campaigns will be performed there to characterise ffCO2-to-coemitted species ratios (CO and NO2) taking advantage of existing air-quality networks, as well as in Eastern Europe (Russia) with activities related to WP3.
Based on the detailed emission mapping model and emission ratios, VERIFY will develop the first atmospheric inversions to monitor specifically ffCO2 emissions. These systems will use CO and NO2 from satellites covering the last 10 years (IASI, MOPITT, OMI) innovating on recent work [Konovalov et al. (2016)]. This atmospheric inversion, oriented to quantify ffCO2 emissions (called Fossil Fuel Data Assimilation System; FFDAS), will provide independent estimates of emissions at 50 km resolution with full uncertainty structure and will be later integrated in the CIF Framework. Complementary research tasks will be conducted to improve FFDAS. With the advent of new satellites, the space sector will become progressively more important for a future ffCO2 monitoring system. We will explore the potential of space-borne measurements of CO2 (GOSAT, OCO2) and reactive trace gases, and the potential of using other observations (i.e. socio-economic), to improve the FFDAS.


Natural CO2 sources and sinks and carbon stocks (WP3)
The objective of WP3 is to provide accurate estimates of ecosystem CO2 fluxes (NEE) based on land observations and ecosystem models capable of producing: i) estimates of NEE at high resolution (≈ 10 km, weekly) for all land use types and ii) attribution of NEE to land use, management intensity and climate drivers.
A first task will collate all needed input data for ecosystem models, including new high-resolution gridded climate fields, land cover changes, management intensity and carbon stocks (biomass and soils). In addition, soil carbon erosion, nitrogen deposition as well as all lateral carbon from lakes and rivers, coastal oceans, and human appropriation of ecosystem resources (harvested products) will be collected. The ecosystem models (see figure 6) will provide high-resolution (≈10 km, weekly) estimates of NEE split into its components (Gross Primary Production, Respiration, disturbances) and carbon stock (biomass and soil). Factorial simulations will allow us to disentangle the contribution of different drivers (climate, CO2, N deposition, management, and land cover change). Model evaluation and recommendation for model selection and improvement for an operational observation-based monitoring and verification system will be drawn.
The second task consists in integrating a regional (higher resolution than global models) atmospheric inversion following the Jena Carboscope approach nested into a global CO2 inversion (Kountouris et al., 2016, http://www.bgc-jena.mpg.de/CarboScope/) in order to assimilate ICOS and other atmospheric CO2 data into 50 km maps of NEE, using a priori fluxes from the first task. In the last year of the project, the NEE maps will be additionally provided by the CIF allowing the use of several transport models to estimate NEE uncertainties from transport modelling. Complementary research activities will test the use of a comprehensive Carbon Cycle Data Assimilation System (CCDAS) (Rayner et al. 2005; Peylin et al. 2016) where ecosystem model parameters are jointly optimised from land and atmospheric observations as well as synergies with the FFDAS of WP2. A research task (including campaign measurements in Russia) is also focused on Eastern Europe, potentially a large carbon sink (Reuter et al. 2016), but where fewer observations are currently available.


CH4 and N2O emissions (WP4)
The objective of WP4 is to provide accurate estimates of all types of CH4 and N2O emissions at various scales across the EU combining bottom-up statistical and ecosystem modelling and atmospheric inversions (top-down).
The first task is dedicated to collect all needed input data at high spatial resolution for all types of anthropogenic and natural (wetlands, lakes, rivers) emissions of CH4 and N2O, as well as atmospheric CH4 and N2O concentrations from surface networks (e.g. ICOS) and satellites (for CH4). Then, we will integrate a number of complementary bottom-up models using input forcing data on climate and management (see WP3). In a second task, we will run regional atmospheric inversions specifically for CH4 and N2O. This will allow WP4 to provide spatio-temporally resolved CH4 and N2O fluxes at 50 km, weekly. In the last year, the CIF will integrate these inversions in a common, unified system, allowing the use of several transport models to estimate the associated uncertainties.
Complementary research activities will develop a specific data assimilation system for wetland fluxes of CH4, develop methods to assimilate new satellite CH4 data (TROPOMI on Sentinel 5P) into regional inversions, and specific tracers (ethane and δ13C) to better separate and attribute CH4 emissions to different sectors, and develop the prototype of an advanced very high resolution inversion (≈ 10 km).

WP5 - Synthesis and products

The main objective of WP5 is to synthesise observation-based estimates of GHG fluxes and carbon stocks from WPs 2 to 4 to deliver Product 3 in preparation for comparison and potential reconciliation with official country-level UNFCCC emission inventories. This process will identify systematic differences that may require scientifically justified corrections (e.g. harmonise system boundaries). The remaining differences may reveal more conceptual issues when comparing inversions to bottom-up emissions mapping and ecosystem models, which limit the extent to which the differences can be resolved in a reconciliation process. These problems have been shown in continental scale carbon budgets (Canadell et al., 2011) to vary considerably between terrestrial regions, also depending on whether land use, fossil fuel emissions or biospheric emissions are the main source. WP5 will perform a thorough uncertainty assessment of GHG budget estimates at national and sub-national scales, identifying both systematic and parametric uncertainties. This process will be systematically improved each year, with feedback to WPs 2, 3 and 4 to provide comprehensive assessments of GHG budgets, with supporting peer-reviewed synthesis publications and the GHG budget fact sheet documents (in collaboration with WP6). An additional novelty will be to analyse recent trends in the GHG budgets, in order to propose future predictions of anthropogenic emissions, facilitating a move towards real-time verification. Analysis of ecosystem carbon-climate feedbacks (how NEE responds to climate anomalies) will be used to better understand the vulnerability of carbon stocks and non-CO2 emissions, with a focus on extreme events (e.g., droughts). This massive synthesis effort will follow a precise well-defined timeline enabling yearly updates, detailed in Figure 6, suited for future operationalization and use by stakeholders and policy makers.

WP6 - Policy-relevant GHG monitoring and verification system design

WP6 will lay the foundations for the prototype of an observation-based GHG monitoring and verification system with the database and data-management system at the project level and policy-relevant information developed from the synthesis of WP5, consisting in a web-based visualization of the evolving trends of GHG fluxes, and a geographic mapping of the emission uncertainty reduction potential from new observations. WP6 will focus not only on the reconciliation between UNFCCC inventories and observation-based estimates from WP5 for each EU country but also for EU as a whole, providing Product 4 in collaboration with WP1. The total observation-based GHG budget of the EU will be derived for 2005-2015 and then yearly updated/extended to the previous year. This will be taken up in the dynamic visualization tools that will embed historical time-series of UNFCCC inventories since 1990. The trends (and uncertainties) will be put in perspective with the NDC targets of 2030 (40% less GHG emissions than in 1990 for EU as a whole), so that policy makers can derive the climate action progress of GHG mitigation at MS and EU level.
The transition between the VERIFY pre-operational but research-based activities and the future operational Monitoring and Verification system being planned in the Copernicus programme, will be documented in the System Design Document (SDD) being Product 5. ECMWF, as the entrusted entity for the Copernicus Atmosphere Monitoirng Service and Copernicus Climate Change Service, will ensure a direct link with the Copernicus programme and facilitate uptake of the results from VERIFY in the Copernicus operational environment. The actionable policymaker support tool in this task will contribute in particular to the roadmap being elaborated by the Copernicus programme for a future operational monitoring system of GHG emissions, described by Ciais et al. (2015).


The VERIFY methodologies from WPs 2 to 5 will also be applied in collaboration with foreign partners for the US, China, and Indonesia to provide Product 6. Existing collaborations with US and Chinese experts in the scientific community and national inventory agencies will provide the additional regional data needed16. Workshops with official agencies and academic institutions are planned to bridge the gap between two communities: the one on emission inventory reporting and the other on observation-based monitoring of GHG sources and sinks. WP will build on the long-standing experience of several partners (the Inventory National Agencies, JRC) in supporting policy makers (e.g. DG Climate Action), and organise regular feedback between the “user requirements of policy makers” and the continued development of the observation-based GHG monitoring and verification system.

WP7 - Input to international programmes and society

WP7 will ensure that the actions of VERIFY will be fully integrated and world leading, building on those activities that have demonstrated track records of delivering useful, policy-relevant information. This will happen mainly at two levels: (1) since the guidelines for verification are still under construction as there are many questions about the details of how to compare EU emissions with other regions and how to best build protocols and interfaces, the VERIFY innovations have to be integrated into an international science-based framework such as the Global Carbon Project17 (GCP) which provides annual Carbon Budgets and recently released a Global CH4 budget (in 2017, the N2O budget). The EU supported those kind of activities in the past resulting in good uptake of its own principles, e.g. by financially supporting the GCP via EU projects during 2008-2015. (2) ICOS ERIC as an ESFRI Research Infrastructure and other European research institutions in the VERIFY consortium contribute to the Integrated Global Greenhouse Gas Information System18 (IG3IS) by the World Meteorological Organisation (WMO) and the Carbon and Greenhouse Gases Initiative of the Group on Earth Observation (GEO-C initiative19). These initiatives also work towards the Global Climate Observing System (GCOS) wihch is obliged to periodically report to the UNFCCC-SBSTA on the status and development in the global observing systems for climate, and are aligned with the CEOS Carbon Monitoring from Space priorities20. GCOS has recently launched its new Implementation Plan “The Global System for Climate: Implementation Needs”. This plan addresses the Paris Agreement and responds to the growing need for systematic observations including GHG for the provision of climate services. Within an envisaged cooperation between VERIFY and GCOS and UNFCCC we will provide regular information from carbon observation and support SBSTA with actual concepts to provide knowledge from data and modelling as resulting from the VERIFY project.

WP2, 3 and 4 will perform the research needed for a pre-operational policy-relevant GHG observation system. The three WPs cover the data collection and development of advanced algorithms for the estimation of fossil fuel combustion CO2 emissions (WP2), terrestrial CO2 sources and sinks and carbon stocks (WP3) and all types of CH4 and N2O emissions (WP4). This will provide Product 1 and Product 2. WP2, 3 and 4 follow the same follow a common structure that includes: i) the collection and processing of all needed input data with yearly updates, ii) the integration into pre-operational systems of bottom-up models currently developed for research applications (ecosystem models, very detailed emission mapping models) and atmospheric inversion models and iii) targeted research actions to further improve these model tools to use recent and upcoming space-borne observations and develop cutting-edge new model data fusion techniques. For the bottom-up component, selected models will be integrated under the same protocol to deliver annual GHG flux maps at 10 km, weekly across the EU (covering all land use types and emission sectors). For the top-down component, there will be two stages: in the first stage we will use existing inversion systems to provide GHG flux estimates at 50 km, weekly resolution during the first three years of the project, then, in the second stage, a unified Community Inversion Framework (CIF, see text-box) that will be built to integrate different transport models and inversions, paving the way for a future operational system. Observation-based methods to quantify fossil fuel combustion CO2 emissions (WP2) Improving and independently verifying fossil15 fuel CO2 (ffCO2) budgets on the national scale, for reporting to the UNFCCC, and for regional emission hot spots (e.g. large urban areas) have a high political priority. However, current CO2 observation systems are not well suited to quantify ffCO2 on either spatial scale. To address this challenge, WP2 will develop a dynamic emission-mapping model that will ingest near-real-time activity data (e.g., energy demand, traffic intensities, socio-economic drivers) and proxies for predictive modelling of these activities (e.g. meteorology), and will further optimise the resulting emission estimates using various independent data streams. This model will provide high spatially (< 10 km) and temporally (hourly) resolved emissions of ffCO2 and of co-emitted species. The model output will be evaluated using isotopes and tracer measurements collected over the selected hotspot region of the Rhine valley (Germany). Several measurement campaigns will be performed there to characterise ffCO2-to-coemitted species ratios (CO and NO2) taking advantage of existing air-quality networks, as well as in Eastern Europe (Russia) with activities related to WP3. Based on the detailed emission mapping model and emission ratios, VERIFY will develop the first atmospheric inversions to monitor specifically ffCO2 emissions. These systems will use CO and NO2 from satellites covering the last 10 years (IASI, MOPITT, OMI) innovating on recent work [Konovalov et al. (2016)]. This atmospheric inversion, oriented to quantify ffCO2 emissions (called Fossil Fuel Data Assimilation System; FFDAS), will provide independent estimates of emissions at 50 km resolution with full uncertainty structure and will be later integrated in the CIF Framework. Complementary research tasks will be conducted to improve FFDAS. With the advent of new satellites, the space sector will become progressively more important for a future ffCO2 monitoring system. We will explore the potential of space-borne measurements of CO2 (GOSAT, OCO2) and reactive trace gases, and the potential of using other observations (i.e. socio-economic), to improve the FFDAS. Natural CO2 sources and sinks and carbon stocks (WP3) The objective of WP3 is to provide accurate estimates of ecosystem CO2 fluxes (NEE) based on land observations and ecosystem models capable of producing: i) estimates of NEE at high resolution (≈ 10 km, weekly) for all land use types and ii) attribution of NEE to land use, management intensity and climate drivers. A first task will collate all needed input data for ecosystem models, including new high-resolution gridded climate fields, land cover changes, management intensity and carbon stocks (biomass and soils). In addition, soil carbon erosion, nitrogen deposition as well as all lateral carbon from lakes and rivers, coastal oceans, and human appropriation of ecosystem resources (harvested products) will be collected. The ecosystem models (see figure 6) will provide high-resolution (≈10 km, weekly) estimates of NEE split into its components (Gross Primary Production, Respiration, disturbances) and carbon stock (biomass and soil). Factorial simulations will allow us to disentangle the contribution of different drivers (climate, CO2, N deposition, management, and land cover change). Model evaluation and recommendation for model selection and improvement for an operational observation-based monitoring and verification system will be drawn. The second task consists in integrating a regional (higher resolution than global models) atmospheric inversion following the Jena Carboscope approach nested into a global CO2 inversion (Kountouris et al., 2016, http://www.bgc-jena.mpg.de/CarboScope/) in order to assimilate ICOS and other atmospheric CO2 data into 50 km maps of NEE, using a priori fluxes from the first task. In the last year of the project, the NEE maps will be additionally provided by the CIF allowing the use of several transport models to estimate NEE uncertainties from transport modelling. Complementary research activities will test the use of a comprehensive Carbon Cycle Data Assimilation System (CCDAS) (Rayner et al. 2005; Peylin et al. 2016) where ecosystem model parameters are jointly optimised from land and atmospheric observations as well as synergies with the FFDAS of WP2. A research task (including campaign measurements in Russia) is also focused on Eastern Europe, potentially a large carbon sink (Reuter et al. 2016), but where fewer observations are currently available. CH4 and N2O emissions (WP4) The objective of WP4 is to provide accurate estimates of all types of CH4 and N2O emissions at various scales across the EU combining bottom-up statistical and ecosystem modelling and atmospheric inversions (top-down). The first task is dedicated to collect all needed input data at high spatial resolution for all types of anthropogenic and natural (wetlands, lakes, rivers) emissions of CH4 and N2O, as well as atmospheric CH4 and N2O concentrations from surface networks (e.g. ICOS) and satellites (for CH4). Then, we will integrate a number of complementary bottom-up models using input forcing data on climate and management (see WP3). In a second task, we will run regional atmospheric inversions specifically for CH4 and N2O. This will allow WP4 to provide spatio-temporally resolved CH4 and N2O fluxes at 50 km, weekly. In the last year, the CIF will integrate these inversions in a common, unified system, allowing the use of several transport models to estimate the associated uncertainties. Complementary research activities will develop a specific data assimilation system for wetland fluxes of CH4, develop methods to assimilate new satellite CH4 data (TROPOMI on Sentinel 5P) into regional inversions, and specific tracers (ethane and δ13C) to better separate and attribute CH4 emissions to different sectors, and develop the prototype of an advanced very high resolution inversion (≈ 10 km).