Gusti, M.

Jonas, M.

International Institute for Applied Systems Analysis (IIASA)

Geophysical Research Abstracts,Vol. 10, EGU2008-A-09464, 2008SRef-ID: 1607-7962/gra/EGU2008-A-09464EGU General Assembly 2008© Author(s) 2008How well do we know Russia’s carbon budget for1988-1992? Critical look from uncertainty study ofIIASA’s Full Carbon AccountM. Gusti (1,2), M. Jonas (1)(1) International Institute for Applied Systems Analysis, Austria, (2) Lviv National PolytechnicUniversity, Ukraine (gusti@iiasa.ac.at / Fax: +43 2236 807-599 / Phone: +43 2236 807-357)How much improvement in the carbon budget estimates for the past period can weexpect if investing more efforts in the study? A target can be set by Shvidenko andNilsson (2007), who concluded the uncertainty for NBP from the thorough study ofthe Siberia-II region 84% (90% confidence interval hereafter). In principle, such animprovement could be reached for the whole Russia. But the improvement is a bittricky because not much new direct knowledge can be added to the past period. Majorinformation is added from applying new studies to reprocessing old data (e.g., fineroot net primary production (NPP), soil respiration measurement inter-comparison)and development of new mathematical models. Critical point is heterotrophic soil res-piration, which suffer from lack of measurements over vast Siberian territories.We studied uncertainties in estimates of major CO2 fluxes between the atmosphereand terrestrial ecosystems for 1988-1992. Our study was centered around the FullCarbon Account for Russia (Nilsson al., 2000) and used a number of recent studies.Much attention was paid to NPP and heterotrophic soil respiration (HR) as they de-termine the uncertainty of the atmospheric CO2 budget. The fluxes were estimated bybioclimatic zones (BCZ) and land-use classes (LU). Systematic errors were identified(to the extent possible) while uncertainties were estimated from a conservative pointof view. Under the given data, uncertainties determined at the spatial scale of BCZsappear robust. HR and NPP uncertainties exceed 100% at finer resolutions.Our NPP estimate for Russia’s arable land is 739 TgC/yr with an uncertainty of 25%.Major reasons of uncertainty are uncertain yield (at oblast level) and yield losses.We used a revised forest NPP estimate by Shvidenko et al. (2006), which is 36%greater than the estimate by Nilsson et al. (2000) (2,329 TgC/yr). The major reasonfor the shift is additional knowledge of fine root NPP. Uncertainty of the forest NPPis 14%. The re-derived NPP estimates for Russia’s wetlands and grasslands & shrubsare 539 TgC/yr ± 53% and 1055 TgC/yr ± 40%, respectively.The new estimate of the HR is 2,920 TgC/yr and the uncertainty 24%. The majorreason of this high uncertainty is lack of spatial and temporal coverage of measure-ments of total soil respiration and root contribution. Some improvement is achievedby adding knowledge on soil respiration measurement biases, recent studies of rootcontribution and structuring the measurements by soil divisions, BCZ and LU.Uncertainty of national totals of fluxes caused by disturbances (240 TgC/yr) and con-sumption (545 TgC/yr) are 21% and 18% respectively. National total components ofdisturbances and consumption are distributed among BCZs proportionally to popula-tion, actual harvest and ‘insect index’ spatial data.The uncertainty of Russia’s net atmospheric balance is approximately 100% centeringaround 957 TgC/yr.For comparison with top-down estimates we upscaled the net atmospheric CO2 fluxto Eurasia (-2.1 PgC/yr) and Extratropical Northern Hemisphere (-3.3 PgC/yr). There-estimated net fluxes are about two times smaller than the top-down estimate byHouse et al. (2003) (-0.94 and -1.45 PgC/yr for Eurasia and Extratropical NorthernHemisphere, respectively). But respective new upscaled uncertainty intervals containaverages of the estimates by House et al. (2003) and their uncertainty intervals (exceptfor one point). Our upscaled value and its uncertainty for the Northern Hemisphereoverlaps well with the corresponding interval (-0.4 – -0.23 PgC/yr) given by Denmanet al. (2007) for 1992-1996. For Northern Asia our uncertainty interval is in the sameorder as given by top-down estimates.ReferencesDenman, K.L. et al., 2007: Couplings Between Changes in the Climate System andBiogeochemistry. In: Climate Change 2007: The Physical Science Basis. Contributionof Working Group I to the Fourth Assessment Report of the Intergovernmental Panel onClimate Change [Solomon, S. et al. (eds.)]. Cambridge University Press, Cambridge,United Kingdom and New York, NY, USA, 499–587.House, J.I. et al., 2003: Reducing apparent uncertainties in estimates of terrestrial CO2sources and sinks. Tellus, 55B, 345–363.Nilsson, S. et al., 2000: Full Carbon Account for Russia. Interim Report, IR-00-021,International Institute for Applied Systems Analysis, Laxenburg, Austria, pp. 180.Shvidenko, A.Z. et al., 2006: Dynamics of net primary production of Russian forestsin a changing world: A new estimate. International Conference: Climate Changes andTheir Impact on Boreal and Temperate Forests, 5–7 June, Abstracts, Ekaterinburg,Russia, 90.Shvidenko A., Nilsson S., 2007: Can the Level of Uncertainties of a Regional Terres-trial Biota Full Carbon Account be Made Acceptable for Policy Makers? 2nd Interna-tional Workshop on Uncertainty in Greenhouse Gas Inventories, Laxenburg, Austria,181–194.

How well do we know Russia's carbon budget for 1988-1992? Critical look from uncertainty study of IIASA's full carbon account

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