|Paper title||Assessments of in situ and remotely sensed CO2 observations in a Carbon Cycle Fossil Fuel Data Assimilation System to estimate fossil fuel emissions|
|Form of presentation||Poster|
Limiting global warming to below 2 degrees Celsius as agreed upon in the Paris agreement requires substantial reductions in fossil fuel emissions. The transparency framework for anthropogenic carbon dioxide (CO2) emissions of the Paris Agreement is based on inventory-based national greenhouse gas emission reports, which are complemented by independent estimates derived from atmospheric CO2 measurements combined with inverse modelling. Such a Monitoring and Verification Support (MVS) capacity is planned to be implemented as part of the EU’s Copernicus programme, however, its ability to constrain fossil fuel emissions to a sufficient extent has not yet been assessed. The CO2 Monitoring (CO2M) mission, planned as a constellation of satellites measuring column-integrated atmospheric CO2 concentration (XCO2), is expected to become a key component of an MVS capacity.
Here we provide an assessment of the potential of a Carbon Cycle Fossil Fuel Data Assimilation System using synthetic XCO2 and other observations to constrain national fossil fuel CO2 emissions for an exemplary 1-week period in 2008 at global scale. We find that the system can provide useful weekly estimates of country-scale fossil fuel emissions independent of national inventories. When extrapolated from the weekly to the annual scale, uncertainties in emissions are comparable to uncertainties in inventories, so that estimates from inventories and from the MVS capacity can be used for mutual verification.
We further demonstrate an alternative, synergistic mode of operation, which delivers a best emission estimate through assimilation of the inventory information as an additional data stream. We show the sensitivity of the results to the setup of the CCFFDAS and to various aspects of the data streams that are assimilated, including assessments of surface networks, the number of CO2M satellites flying in constellation, and the assumed uncertainties in the XCO2 measurements. We also assess the impact of additional observational data streams such as radiocarbon in CCFFDAS on constraining fossil fuel emissions.