There is a new research paper on the assessment of terrestrial carbon fluxes into the atmosphere associated with land use change and forestry [and thanks to Timo Hämeranta for alerting us to it!].
The paper is
Ito, Akinori, J. E. Penner, M. J. Prather, C. P. de Campos, R. A. Houghton, T. Kato, A. K. Jain, X. Yang, G. C. Hurtt, S. Frolking, M. G. Fearon, L. P. Chini, A. Wang, and D. T. Price, 2008. Can we reconcile differences in
estimates of carbon fluxes from land-use change and forestry for the 1990s? Atmospheric Chemistry and Physics Vol. 8, No 12, pp. 3291-3310, June 27, 2008, online
The abstract of the paper reads,
“The effect of Land Use Change and Forestry (LUCF) on terrestrial carbon fluxes can be regarded as a carbon credit or debit under the UNFCCC, but scientific uncertainty in the estimates for LUCF remains large. Here, we assess the LUCF estimates by examining a variety of models of different types with different land cover change maps in the 1990s. Annual carbon pools and their changes are separated into different components for separate geographical regions, while annual land cover change areas and carbon fluxes are disaggregated into different LUCF activities and the biospheric response due to CO2 fertilization and climate change. We developed a consolidated estimate of the terrestrial carbon fluxes that combines book-keeping models with process-based biogeochemical models and inventory estimates and yields an estimate of the global terrestrial carbon flux that is within the uncertainty range developed in the IPCC 4th Assessment Report. We examined the USA and Brazil as case studies in order to assess the cause of differences from the UNFCCC reported carbon fluxes. Major differences in the litter and soil organic matter components are found for the USA. Differences in Brazil result from assumptions about the LUC for agricultural purposes. The effects of CO2 fertilization and climate change also vary significantly in Brazil. Our consolidated estimate shows that the small sink in Latin America is within the uncertainty range from inverse models, but that the sink in the USA is significantlysmaller than the inverse models estimates. Because there are different sources of errors at the country level, there is no easy reconciliation of different estimates of carbon fluxes at the global level. Clearly, further work is required to develop data sets for historical land cover change areas and models of biogeochemical changes for an accurate representation ofcarbon uptake or emissions due to LUC.”
This is an important study as it highlights uncertainties associated with the global carbon budget. However, what the authors did not do was assess how the land use changes and forestry practices altered the regional and global radiative climate forcing!
Without such a simulataneous assessment, the research is serously incomplete, as has been discussed, for example, in
Pielke Sr., R.A., 2001: Carbon sequestration — The need for an integrated climate system approach. Bull. Amer. Meteor. Soc., 82, 2021,
where it is written that
“There has, unfortunately, been no attempt to evaluate the benefit of carbon sequestration as a means of reducing the concentrations of the radiatively active gas CO2 in the atmosphere, while at the same time, assessing the influence of this sequestration on the radiatively active gas H2O, and on the surface heat energy budget. Until these effects are factored in as part of an integrated climate assessment, a policy based on carbon sequestration as a means to reduce the radiative warming effect of increased atmospheric concentrations of CO2 could actually enhance this warming.”
There is a research opportunity for the climate science community to expand the Ito et al 2008 study to include the effect of land-use change and forestry practices in the 1990s on regional and global radiative forcing.