Towards an operational anthropogenic CO2 emissions monitoring and verification support capacity

Abstract Under the Paris Agreement, progress of emission reduction efforts is tracked on the basis of regular updates to national Greenhouse Gas (GHG) inventories, referred to as bottom-up estimates. However, only top-down atmospheric measurements can provide observation-based evidence of emission trends. Today, there is no internationally agreed, operational capacity to monitor anthropogenic GHG emission trends using atmospheric measurements to complement national bottom-up inventories. The European Commission (EC), the European Space Agency, the European Centre for Medium-Range Weather Forecasts, the European Organisation for the Exploitation of Meteorological Satellites and international experts are joining forces to develop such an operational capacity for monitoring anthropogenic CO2 emissions as a new CO2 service under EC's Copernicus Programme. Design studies have been used to translate identified needs into defined requirements and functionalities of this anthropogenic CO2 emissions Monitoring and Verification Support (CO2MVS) capacity. It adopts a holistic view and includes components such as atmospheric space-borne and in-situ measurements, bottom-up CO2 emission maps, improved modeling of the carbon cycle, an operational data-assimilation system integrating top-down and bottom-up information, and a policy-relevant decision support tool. The CO2MVS capacity with operational capabilities by 2026, is expected to visualize regular updates of global CO2 emissions, likely at 0.05°x0.05°. This will complement the PA’s enhanced transparency framework, providing actionable information on anthropogenic CO2 emissions that are the main driver of climate change. This information will be available to all stakeholders, including governments and citizens, allowing them to reflect on trends and effectiveness of reduction measures. The new EC gave green light to pass the CO2MVS from exploratory to implementing phase. 1. Policy contextSince the establishment of the United Nations Framework Convention on Climate Change (UNFCCC) 25 years ago, many actions have been undertaken by the Conference of Parties (COP) and the Intergovernmental Panel for Climate Change (IPCC), but global emissions of Greenhouse Gases (GHGs) have not yet been curbed. In 2015, transparency and collaborative efforts were high on the agenda . This concluded with the Paris Agreement (PA) (UNFCCC, 2015), representing a paradigm shift because it downplays the distinction between Annex-I (developed) and non-Annex-I (developing) Parties for committing to emission reduction and establishes an enhanced transparency framework, freely accessible to all Parties. The enhanced transparency framework builds on the Monitoring–Reporting–Verifying framework, under which Parties provide their national GHG inventories compiled in line with the IPCC (2006) Guidelines.The UNFCCC's Subsidiary Body for Scientific and Technological Advice (UNFCCC-SBSTA, 2017, 2019) as well as the IPCC Task Force on the 2019 Refinement to the 2006 Guidelines (IPCC-TFI, 2019) acknowledged the complementary capability offered by GHGs monitoring through in-situ as well as satellite observations. Currently, only a few countries (UK, Switzerland, Australia and New Zealand) complement their national inventory data, based on annual statistics of human activities, with atmospheric observations (Bergamaschi et al., 2018). More encouragement is needed to bridge the gap between the IPCC Task Force on inventories, the IPCC Working Groups for assessments, and more generally the science community involved in atmospheric GHG measurements and flux estimation (e.g., Le Quéré et al., 2018). From 2023 onwards, the IPCC is expected to provide important input to the review of the national GHG inventories at the biennial Facilitative Multilateral Considerations of Progress (FMCP) or the five-yearly Global Stocktake (GST). Responding to the policy impetus at national, European Union (EU) and global scales, an expert panel from the European Commission (EC), Pinty et al. (2019), identified the high-level needs of Table 1 that have been translated into technical requirements. Responsibilities and commitments are not only taken at governmental level, but also by cities (e.g., the Covenant of Mayors), power-plant operators, oil/gas multinationals, and more. Multi-level governance schemes, involving municipal, regional and national authorities, ask for GHG monitoring, not only with annual national totals, but also with spatiotemporally resolved emissions. The tracking of emission reductions, as intended under the Nationally Determined Contributions (NDC), is facilitated by higher spatial resolution. As shown for air pollutants, the Convention of Long-Range Transboundary Air Pollution (UNECE-CLRTAP, 2013) imposed from 2014 onwards that Parties report emissions (including point sources) on spatial grids.