[M-IS01] Environmental, Socio-Economic and Climatic Changes in Northern Eurasia

[MIS01-01] Recent changes in land carbon sink estimates by inventories and models for Russia, a review

*Shamil Maksyutov¹ (1.National Institute for Environmental Studies)

キーワード：carbon sink, top-down , national inventory

Understanding regional terrestrial carbon sinks and their sensitivity to climate change is important for the predictability of the global climate system's response to greenhouse gas emissions. High-latitude and boreal land ecosystems appear as sizable but difficult to quantify carbon sinks. The bottom-up sink data for Russia have potential to provide an important calibration for global models. Progress has been made in the last decade toward improving the estimates of the land carbon sink for Russia since the summary published by the RECCAP project in 2013. The estimates are made by (1) bottom-up inventories, based on forestry and agricultural data, supported by remote sensing (2) global biogeochemical process-based models (3) scaling up the direct CO2 flux observations at fixed locations to the country area (4) an atmospheric inverse modeling. The land sink by Russia’s National Inventory Report (NIR) in RECCAP did not change significantly (155 TgC/year in 2020). Back in 2013, the process-based models gave a conservative estimate of 90 TgC/year while other flux tower observations, bottom-up inventories, inverse models and estimated bigger annual sinks of 342, 682 and 1350 TgC, so the diverging results were difficult to reconcile. More recent estimates by the Global Carbon Budget 2020 and bottom-up data point to a large improvement and better agreement between different approaches. A number of inverse models now give estimates closer to NIR, while biogeochemical models improved to the level of accommodating the global sinks of ~3-4 PgC/year and more than 300 TgC for Russia alone, which agrees better with the estimates by remote sensing and flux tower observations which are now in the range of 350-600 TgC/year. Still, further effort to improve the sink estimates by all methods is needed due to remaining discrepancies between NIR (now appears most conservative) and other approaches.