Bastos, AnaCiais, PhillippeSitch, StephenAragão, Luiz O. C.Chevallier, FrédéricFawcett, DominicRosan, Thais M.Saunois, MarielleGünther, DirkPerugini, LuciaRobert, ColasDeng, ZhuPongratz, JuliaGanzenmüller, RaphaelFuchs, RichardWinkler, KarinaZaehle, SönkeAlbergel, Clément2023-03-312023-03-312022-10-01Bastos, A., Ciais, P., Sitch, S. et al. On the use of Earth Observation to support estimates of national greenhouse gas emissions and sinks for the Global stocktake process: lessons learned from ESA-CCI RECCAP2. Carbon Balance Manage 17, 15 (2022). https://doi.org/10.1186/s13021-022-00214-whttps://doi.org/10.1186/s13021-022-00214-whttps://hdl.handle.net/20.500.14096/316© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. The Version of Scholarly Record of this Article is published in Carbon Balance and Management, 2022, available online at: https://cbmjournal.biomedcentral.com/articles/10.1186/s13021-022-00214-w . Keywords: Paris agreement, Greenhouse gases, Carbon dioxide, Methane, Land-use change, Earth observation.The Global Stocktake (GST), implemented by the Paris Agreement, requires rapid developments in the capabilities to quantify annual greenhouse gas (GHG) emissions and removals consistently from the global to the national scale and improvements to national GHG inventories. In particular, new capabilities are needed for accurate attribution of sources and sinks and their trends to natural and anthropogenic processes. On the one hand, this is still a major challenge as national GHG inventories follow globally harmonized methodologies based on the guidelines established by the Intergovernmental Panel on Climate Change, but these can be implemented diferently for individual countries. Moreover, in many countries the capability to systematically produce detailed and annually updated GHG inventories is still lacking. On the other hand, spatially-explicit datasets quantifying sources and sinks of carbon dioxide, methane and nitrous oxide emissions from Earth Observations (EO) are still limited by many sources of uncertainty. While national GHG inventories follow diverse methodologies depending on the availability of activity data in the diferent countries, the proposed comparison with EO-based estimates can help improve our understanding of the comparability of the estimates published by the diferent countries. Indeed, EO networks and satellite platforms have seen a massive expansion in the past decade, now covering a wide range of essential climate variables and ofering high potential to improve the quantifcation of global and regional GHG budgets and advance process understanding. Yet, there is no EO data that quantifes greenhouse gas fuxes directly, rather there are observations of variables or proxies that can be transformed into fuxes using models. Here, we report results and lessons from the ESA-CCI RECCAP2 project, whose goal was to engage with National Inventory Agencies to improve understanding about the methods used by each community to estimate sources and sinks of GHGs and to evaluate the potential for satellite and in-situ EO to improve national GHG estimates. Based on this dialogue and recent studies, we discuss the potential of EO approaches to provide estimates of GHG budgets that can be compared with those of national GHG invento ries. We outline a roadmap for implementation of an EO carbon-monitoring program that can contribute to the Paris Agreement.enArticle